Evidence record
Is empty space empty?
Every sentence on the exploration belongs to at least one claim below. Each says what kind of statement it is, what it rests on, what the evidence does not establish, and how far it was checked. Nothing here is a score, and none of it is a verdict on a belief or a theory.
Last checked 24 September 2026.
- Source checked: 40
- A judgement, not a fact: 8
- Partly checked: 3
- Presented as open: 2
If something here is wrong, misquoted, out of date or unfair, write to support@unknownoceans.com and give the claim number, which does not change.
What the question takes for granted
A physics question with a definitional one inside it: in quantum field theory "empty" means the lowest energy state of the fields, which has measurable effects and a predicted energy that disagrees with cosmology by dozens of orders of magnitude. Whether the Casimir force shows that energy is real is disputed.
Empty space means a region with no particles in it
Contested
In quantum field theory the vacuum is the lowest energy state rather than a count of zero, and on many readings of the Unruh effect the number of particles depends on the observer. The page reports both.
The vacuum’s zero-point energy is physically real
Contested
The standard account says so and cites the Casimir force; Jaffe 2005 argues the force does not show it, and Martin 2012 holds the fluctuations are still needed by the theory.
The vacuum’s energy gravitates like any other energy
Open
Assumed in stating the cosmological constant problem; no laboratory measurement tests it, and Martin 2012 treats abnormal gravitational properties of the vacuum as a live possibility.
How the question is labelled
Claim: The pressure of nothing
- Kind
- Framing. Signposting. It asserts nothing a source could check.
Claim: The vacuum
- Kind
- Framing. Signposting. It asserts nothing a source could check.
The question
Claim: Two uncharged plates in a vacuum are pushed together by a force
- Kind
- Experimental result. What an experiment or trial found, under its own conditions. A result in animals, cells or a simulation is not a result in people.
- Review
- Source checked. The cited passage was read, and it says this.
Supports
Measurement of the Casimir Force between Parallel Metallic Surfacesintroduction, third paragraph; equation 4 and following
Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Physical systems · Experiment
The source reads: this Letter we report on the measurement of the Casimir force ... parallel conducting ... The value obtained agrees with the expected value of KC first evaluated by Casimir
Supports
Measurement of the Casimir Force between Parallel Metallic Surfacesabstract
Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Physical systems · Experiment
The source reads: the related force coefficient was determined at ... 15% precision level.
What this does not establish
Measured in the parallel-plate arrangement once, to 15 per cent, by Bressi and others in 2002; most precise measurements use a plate and a sphere.
Later work looked for
Crossref, 2003 on, "Casimir force parallel plates measurement": proposed sub-micron parallel-plate set-ups (2010, 2011) but nothing that replaces Bressi and others 2002 as the parallel-plate measurement; sphere and plate measurements reached about 1 per cent (as Bressi and others and Jaffe report). Nothing that changes the claim.
Claim 3 · checked 24 September 2026 · AI-assisted audit
Claim: that quantum theory can calculate from the vacuum itself
- Kind
- What a model says. What a theory or model predicts or describes, which is not the same as what has been observed.
- Review
- Source checked. The cited passage was read, and it says this.
Supports
Measurement of the Casimir Force between Parallel Metallic Surfacesintroduction, first paragraph
Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026
The source reads: spaced by a distance d is obtained by summing all the vacuum modes contributions
Supports
Everything you always wanted to know about the cosmological constant problem (but were afraid to ask)section XII.B.1
Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Review of the field
The source reads: The Casimir force arises because of a shift in the vacuum energy when the plates are present
Qualifies
Casimir effect and the quantum vacuumconclusion
Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026
The source reads: Casimir forces can be calculated without reference to the vacuum
The same force can be derived as one between the charges in the plates; see claim 60.
What this does not establish
Whether the vacuum is where the force comes from is disputed: Jaffe 2005 derives the same force from the charges in the plates without reference to the vacuum, and Martin 2012 holds that zero-point fluctuations are still needed in quantum field theory. See claims 60 and 61.
Later work looked for
How the method or model works; not a finding later work revises.
Corrected
24 September 2026. Previously: “Two uncharged plates in a vacuum are pushed together by a force that comes from the vacuum itself, and it has been measured.” "Comes from the vacuum itself" asserted what the page’s own last section says the measurement does not settle: Jaffe 2005 derives the force from the charges in the plates. The standard calculation is from the vacuum, and the subtitle now says that.
Claim 4 · checked 24 September 2026 · AI-assisted audit
Claim: and it has been measured.
- Kind
- Experimental result. What an experiment or trial found, under its own conditions. A result in animals, cells or a simulation is not a result in people.
- Review
- Source checked. The cited passage was read, and it says this.
Supports
Measurement of the Casimir Force between Parallel Metallic Surfacesintroduction, third paragraph; equation 4 and following
Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Physical systems · Experiment
The source reads: this Letter we report on the measurement of the Casimir force ... parallel conducting ... The value obtained agrees with the expected value of KC first evaluated by Casimir
Supports
Measurement of the Casimir Force between Parallel Metallic Surfacesabstract
Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Physical systems · Experiment
The source reads: the related force coefficient was determined at ... 15% precision level.
Later work looked for
Crossref, 2003 on, "Casimir force parallel plates measurement": proposed sub-micron parallel-plate set-ups (2010, 2011) but nothing that replaces Bressi and others 2002 as the parallel-plate measurement; sphere and plate measurements reached about 1 per cent (as Bressi and others and Jaffe report). Nothing that changes the claim.
Claim 5 · checked 24 September 2026 · AI-assisted audit
Claim: In quantum field theory the vacuum is the lowest energy state of a set of fields, not an absence.
- Kind
- What a model says. What a theory or model predicts or describes, which is not the same as what has been observed.
- Review
- Source checked. The cited passage was read, and it says this.
Supports
Quantum Field Theorysection 5.1
Cited · Link answered, 19 October 2026 · The cited passage was read, 24 September 2026 · Reference work
The source reads: is the energy ground state, i.e., the eigenstate of the energy operator with the lowest eigenvalue ... the relativistic vacuum of QFT has the even more striking feature that the expectation values for various quantities do not vanish
Other readings
The entry reports that what the vacuum’s non-vanishing quantities belong to, if nothing is there, is itself a question for the interpretation of the theory.
Later work looked for
How the method or model works; not a finding later work revises.
Claim 6 · checked 24 September 2026 · AI-assisted audit
Claim: It has measurable consequences, including a force between nearby plates.
- Kind
- What a model says. What a theory or model predicts or describes, which is not the same as what has been observed.
- Review
- Source checked. The cited passage was read, and it says this.
Supports
Everything you always wanted to know about the cosmological constant problem (but were afraid to ask)section XII.B.2, "Thirdly"
Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Review of the field
The source reads: the Casimir Force has been observed in the laboratory and this is usually taken as another evidence in favor of the existence of the zero-point fluctuations.
Supports
The cosmological constant problemsection III
Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026
The source reads: despite the demonstration in the Casimir effect of the reality of zero-point energies
Qualifies
Casimir effect and the quantum vacuumconclusion
Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026
The source reads: Casimir forces can be calculated without reference to the vacuum
The same force can be derived as one between the charges in the plates; see claim 60.
What this does not establish
Whether the vacuum is where the force comes from is disputed: Jaffe 2005 derives the same force from the charges in the plates without reference to the vacuum, and Martin 2012 holds that zero-point fluctuations are still needed in quantum field theory. See claims 60 and 61.
Later work looked for
How the method or model works; not a finding later work revises.
Claim 7 · checked 24 September 2026 · AI-assisted audit
Claim: It also has an energy density
- Kind
- What a model says. What a theory or model predicts or describes, which is not the same as what has been observed.
- Review
- Source checked. The cited passage was read, and it says this.
Supports
Casimir effect and the quantum vacuumintroduction, first paragraph
Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026
The source reads: In quantum field theory as usually formulated, the zero point fluctuations of the fields contribute to the energy of the vacuum.
Supports
The cosmological constant problemsection III
Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Review of the field
The source reads: summing the zero-point energies of all normal modes of some field of mass m up to a wave number cutoff
What this does not establish
An energy density that is predicted, not measured in any laboratory; Jaffe 2005 notes it does not seem to be observable in any laboratory experiment.
Later work looked for
How the method or model works; not a finding later work revises.
Claim 8 · checked 24 September 2026 · AI-assisted audit
Claim: and the value that theory predicts for it is wrong
- Kind
- What scholars argue. A report of what specialists argue, or where they disagree.
- Review
- Source checked. The cited passage was read, and it says this.
Supports
Casimir effect and the quantum vacuumintroduction, second paragraph
Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026
The source reads: estimates of the energy density due to zero point fluctuations exceed the measured value of λ by many orders of magnitude.
Supports
Everything you always wanted to know about the cosmological constant problem (but were afraid to ask)section X.A, after equation 548
Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Review of the field
The source reads: the large mismatch between the theoretical expectation (516) and the above, observationally determined, number (548), something like 54 orders of magnitude (but much less than the 122 orders of magnitude often quoted in the literature)
Supports
The cosmological constant problemsection I
Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Review of the field
The source reads: exceed observational limits ... some 120 orders of magnitude
What this does not establish
How wrong depends on the estimate: some 120 orders of magnitude in the simplest one, about 54 in Martin’s renormalised one.
Later work looked for
Crossref, 2018 on, "cosmological constant problem review", and Martin 2012 read in full: the problem is unsolved; Martin finds a properly renormalised mismatch of about 54 orders rather than the often quoted 120 or so, which the page already covers with "dozens".
Claim 9 · checked 24 September 2026 · AI-assisted audit
Claim: by some fifty orders of magnitude on a careful estimate and 120 on the simplest.
- Kind
- What scholars argue. A report of what specialists argue, or where they disagree.
- Review
- Source checked. The cited passage was read, and it says this.
Supports
Everything you always wanted to know about the cosmological constant problem (but were afraid to ask)section X.A, after equation 548
Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Review of the field
The source reads: the large mismatch between the theoretical expectation (516) and the above, observationally determined, number (548), something like 54 orders of magnitude (but much less than the 122 orders of magnitude often quoted in the literature)
Some fifty is 54 rounded down by about seven per cent.
Supports
The cosmological constant problemsection I
Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Review of the field
The source reads: exceed observational limits ... some 120 orders of magnitude
What this does not establish
Martin’s careful estimate renormalises the zero-point energy properly; the 120 is the simple cutoff estimate, compared in 1989 with an observational limit rather than a measured value.
Corrected
24 September 2026. Previously: “by more than any other prediction in physics.” A universal the sources do not make: none ranks the gap against every other prediction in physics. Replaced with the two figures the sources give, about 54 orders of magnitude in Martin 2012's renormalised estimate and some 120 in Weinberg 1989's simplest one.
Claim 10 · checked 24 September 2026 · AI-assisted audit
Claim: Remove every particle from a region and something is left: the fields themselves, in their lowest state, which is not a state of nothing happening.
- Kind
- What a model says. What a theory or model predicts or describes, which is not the same as what has been observed.
- Review
- Source checked. The cited passage was read, and it says this.
Supports
Quantum Field Theorysection 5.1
Cited · Link answered, 19 October 2026 · The cited passage was read, 24 September 2026 · Reference work
The source reads: is the energy ground state, i.e., the eigenstate of the energy operator with the lowest eigenvalue ... the relativistic vacuum of QFT has the even more striking feature that the expectation values for various quantities do not vanish
Supports
Casimir effect and the quantum vacuumintroduction, first paragraph
Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026
The source reads: In quantum field theory as usually formulated, the zero point fluctuations of the fields contribute to the energy of the vacuum.
Other readings
Philosophers of physics dispute what the vacuum’s non-zero quantities belong to; the Stanford Encyclopedia entry sets out the positions.
Later work looked for
How the method or model works; not a finding later work revises.
Claim 11 · checked 24 September 2026 · AI-assisted audit
Claim: That is not a metaphor.
- Kind
- This page’s reading. A judgement the page makes from the evidence. Others read it differently.
- Review
- A judgement, not a fact. Reviewed for whether it is fairly put and follows from the checked claims. No source can confirm it.
Follows from claims 13 and 14: the standard account attributes a measured force to the vacuum. Claim 61 reports that this attribution is disputed.
Claim 12 · checked 24 September 2026 · AI-assisted audit
Claim: On the standard account it exerts a force
- Kind
- What a model says. What a theory or model predicts or describes, which is not the same as what has been observed.
- Review
- Source checked. The cited passage was read, and it says this.
Supports
Everything you always wanted to know about the cosmological constant problem (but were afraid to ask)section XII.B.2, "Thirdly"
Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Review of the field
The source reads: the Casimir Force has been observed in the laboratory and this is usually taken as another evidence in favor of the existence of the zero-point fluctuations.
Supports
The cosmological constant problemsection III
Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026
The source reads: despite the demonstration in the Casimir effect of the reality of zero-point energies
Qualifies
Casimir effect and the quantum vacuumconclusion
Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026
The source reads: Casimir forces can be calculated without reference to the vacuum
The same force can be derived as one between the charges in the plates; see claim 60.
What this does not establish
Whether the vacuum is where the force comes from is disputed: Jaffe 2005 derives the same force from the charges in the plates without reference to the vacuum, and Martin 2012 holds that zero-point fluctuations are still needed in quantum field theory. See claims 60 and 61.
Later work looked for
How the method or model works; not a finding later work revises.
Corrected
24 September 2026. Previously: “It exerts a force that can be measured with a torsion pendulum.” The page’s own final section, following Jaffe 2005, says the measurement does not settle whether the vacuum is what exerts the force. The opening now attributes that to the standard account.
Claim 13 · checked 24 September 2026 · AI-assisted audit
Claim: and the force has been measured with a torsion pendulum.
- Kind
- Experimental result. What an experiment or trial found, under its own conditions. A result in animals, cells or a simulation is not a result in people.
- Review
- Partly checked. Only part of the source could be read. What was not read is listed.
Supports
Demonstration of the Casimir Force in the 0.6 to 6 micrometre Rangeabstract (INSPIRE record)
Cited · Link answered, 19 October 2026 · Abstract only, 24 September 2026 · Physical systems · Experiment
The source reads: The vacuum stress between closely spaced conducting surfaces, due to the modification of the zero-point fluctuations of the electromagnetic field, has been conclusively demonstrated. The measurement employed an electromechanical system based on a torsion pendulum. Agreement with theory at the level of 5% is obtained.
Supports
Measurement of the Casimir Force between Parallel Metallic Surfacesintroduction, second paragraph
Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Physical systems · Experiment
The source reads: only in a particular geometry, namely in a cavity constituted by a plane ... opposing a spherical one ... More recently, these measurements have been revived by using state of art torsion
Supports
The Casimir force between real materials: Experiment and theorysection IV.C.1, Torsion pendulum experiment
Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Review of the field
The source reads: Chronologically, the first experiment, in the more recent series of the Casimir force mea- surements was performed by Lamoreaux (1997). ... The Casimir force between an Au coated spherical lens and a flat plate was measured using a torsion pendulum.
What this does not establish
Lamoreaux 1997 was read only as its abstract; the paper is closed and carries a 1998 erratum that was not read. The torsion pendulum is confirmed by the 2009 review, read in full, which also finds that the paper’s precision was overstated (claim 20).
Later work looked for
Crossref, 2003 on, "Casimir force parallel plates measurement": proposed sub-micron parallel-plate set-ups (2010, 2011) but nothing that replaces Bressi and others 2002 as the parallel-plate measurement; sphere and plate measurements reached about 1 per cent (as Bressi and others and Jaffe report). Nothing that changes the claim.
Claim 14 · checked 24 September 2026 · AI-assisted audit
What is measured
Claim: What is measured
- Kind
- Framing. Signposting. It asserts nothing a source could check.
The Casimir force
Claim: The Casimir force
- Kind
- Framing. Signposting. It asserts nothing a source could check.
Claim: Two conducting plates a fraction of a micrometre apart restrict which field modes can exist between them.
- Kind
- What a model says. What a theory or model predicts or describes, which is not the same as what has been observed.
- Review
- Source checked. The cited passage was read, and it says this.
Supports
Everything you always wanted to know about the cosmological constant problem (but were afraid to ask)section XII.B.1
Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Review of the field
The source reads: the boundary conditions “feel” the presence of the two plates.
Supports
Measurement of the Casimir Force between Parallel Metallic Surfacesintroduction, first paragraph
Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026
The source reads: spaced by a distance d is obtained by summing all the vacuum modes contributions
What this does not establish
An idealised calculation for perfectly conducting plates; real metals need finite-conductivity corrections (Jaffe 2005).
Later work looked for
How the method or model works; not a finding later work revises.
Claim 17 · checked 24 September 2026 · AI-assisted audit
Claim: Fewer modes inside than outside means a pressure difference, pushing the plates together.
- Kind
- What a model says. What a theory or model predicts or describes, which is not the same as what has been observed.
- Review
- Source checked. The cited passage was read, and it says this.
Supports
Everything you always wanted to know about the cosmological constant problem (but were afraid to ask)section XII.B.1
Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Review of the field
The source reads: The Casimir force arises because of a shift in the vacuum energy when the plates are present
Supports
Everything you always wanted to know about the cosmological constant problem (but were afraid to ask)section XII.B.2, "Secondly"
Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Review of the field
The source reads: one is only sensitive to the difference of vacuum energy from one side of the plates to the other.
What this does not establish
This is the zero-point account of the force. Jaffe 2005 calls it heuristic and derives the same force without it; see claim 60.
Later work looked for
How the method or model works; not a finding later work revises.
Claim 18 · checked 24 September 2026 · AI-assisted audit
Claim: Predicted in 1948
- Kind
- Historical claim. A statement about the past that historical evidence can test.
- Review
- Source checked. The cited passage was read, and it says this.
Supports
The cosmological constant problemsection III, footnote on Casimir (1948)
Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026
The source reads: showed that quantum fluctuations in the space between two ... conducting plates with separation d would
Supports
Measurement of the Casimir Force between Parallel Metallic Surfacesintroduction, third paragraph; equation 4 and following
Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Physical systems · Experiment
The source reads: this Letter we report on the measurement of the Casimir force ... parallel conducting ... The value obtained agrees with the expected value of KC first evaluated by Casimir
Claim 19 · checked 24 September 2026 · AI-assisted audit
Claim: and measured in 1997, between a flat plate and a curved surface, at separations between 0.6 and 6 micrometres; its author reported agreement with theory at the five per cent level, which a later review finds could hold only near one micrometre.
- Kind
- Experimental result. What an experiment or trial found, under its own conditions. A result in animals, cells or a simulation is not a result in people.
- Review
- Partly checked. Only part of the source could be read. What was not read is listed.
Supports
Demonstration of the Casimir Force in the 0.6 to 6 micrometre Rangetitle and abstract (INSPIRE record)
Cited · Link answered, 19 October 2026 · Abstract only, 24 September 2026 · Physical systems · Experiment
The source reads: Demonstration of the Casimir force in the 0.6 to 6 micrometers range ... The vacuum stress between closely spaced conducting surfaces, due to the modification of the zero-point fluctuations of the electromagnetic field, has been conclusively demonstrated. ... Agreement with theory at the level of 5% is obtained.
Supports
Measurement of the Casimir Force between Parallel Metallic Surfacesintroduction, second paragraph; reference 11
Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Physical systems · Experiment
The source reads: only in a particular geometry, namely in a cavity constituted by a plane ... opposing a spherical one ... More recently, these measurements have been revived by using state of art torsion ... S. K. Lamoreaux, Phys. Rev. Lett. 78, 5 (1997).
Supports
Casimir effect and the quantum vacuumintroduction
Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026
The source reads: In 1997 Lamoreaux opened the door to precise measurement of
Qualifies
Measurement of the Casimir Force between Parallel Metallic Surfacesintroduction, second paragraph
Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026
The source reads: Pioneering measurements by van Blokland and Overbeek ... resulted in the observation of the associated Casimir force
An observation in the sphere and plate geometry predates 1997; the page does not call 1997 the first.
Supports
The Casimir force between real materials: Experiment and theorysection IV.C.1, Torsion pendulum experiment
Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Review of the field
The source reads: The Casimir force between an Au coated spherical lens and a flat plate was measured using a torsion pendulum.
Qualifies
The Casimir force between real materials: Experiment and theorysection IV.C.1, Torsion pendulum experiment
Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Review of the field
The source reads: agreement at the level of 5% in the 0.6 to 6 µm range (Lamoreaux, 1997) was found to be incompatible with the magnitude of the thermal correction ... the agreement of the data with the theory at the level of 5%–10% may exist only at separations of about 1 µm.
The review puts the possible agreement at 5 to 10 per cent near 1 µm; the page gives only where it could hold.
Qualifies
The Casimir force between real materials: Experiment and theorysection IV.A, first paragraph
Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Review of the field
The source reads: This experiment, however, contains several uncer- tainties that do not permit one to consider it as precise and definitive
Why the page no longer calls the 1997 measurement convincing.
What this does not establish
Lamoreaux’s own paper and its 1998 erratum are closed and were read only as the abstract; the geometry, the range, the five per cent and the later assessment are all in the 2009 review, read in full, which is written by a group that measures the force.
Later work looked for
Crossref, 2003 on, "Casimir force parallel plates measurement": proposed sub-micron parallel-plate set-ups (2010, 2011) but nothing that replaces Bressi and others 2002 as the parallel-plate measurement; sphere and plate measurements reached about 1 per cent (as Bressi and others and Jaffe report). Nothing that changes the claim.
Corrected
24 September 2026. Previously: “Predicted in 1948 and measured convincingly in 1997, at separations between 0.6 and 6 micrometres, with agreement at the five per cent level.” The 1997 measurement was not between two plates, which the section and the subtitle implied. Bressi and others 2002 say every successful measurement to that date used a plane opposite a spherical surface.
24 September 2026. Previously: “and measured convincingly in 1997, between a flat plate and a curved surface, at separations between 0.6 and 6 micrometres, with agreement at the five per cent level.” The five per cent across 0.6 to 6 micrometres is Lamoreaux's own claim, and Klimchitskaya and others 2009 find it incompatible with the thermal correction, which is 86 to 174 per cent of the force at 4 to 6 micrometres: agreement at 5 to 10 per cent may exist only near 1 micrometre, and the review does not count the experiment as precise and definitive. The page stated the range and the precision together as fact, and called the measurement convincing.
Claim 20 · checked 24 September 2026 · AI-assisted audit
Claim: Between two parallel plates, the arrangement Casimir described, it was measured in 2002 to fifteen per cent.
- Kind
- Experimental result. What an experiment or trial found, under its own conditions. A result in animals, cells or a simulation is not a result in people.
- Review
- Source checked. The cited passage was read, and it says this.
Supports
Measurement of the Casimir Force between Parallel Metallic Surfacesintroduction, third paragraph; equation 4 and following
Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Physical systems · Experiment
The source reads: this Letter we report on the measurement of the Casimir force ... parallel conducting ... The value obtained agrees with the expected value of KC first evaluated by Casimir
Supports
Measurement of the Casimir Force between Parallel Metallic Surfacesabstract
Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Physical systems · Experiment
The source reads: the related force coefficient was determined at ... 15% precision level.
Supports
The cosmological constant problemsection III, footnote on Casimir (1948)
Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026
The source reads: showed that quantum fluctuations in the space between two ... conducting plates with separation d would
What this does not establish
One measurement, at separations of 0.5 to 3 micrometres; the authors note the fit misses systematically between 1 and 2 micrometres.
Later work looked for
Crossref, 2003 on, "Casimir force parallel plates measurement": proposed sub-micron parallel-plate set-ups (2010, 2011) but nothing that replaces Bressi and others 2002 as the parallel-plate measurement; sphere and plate measurements reached about 1 per cent (as Bressi and others and Jaffe report). Nothing that changes the claim.
Corrected
24 September 2026. Previously: “” Added so that the page’s plates, in the subtitle and the section, rest on a measurement that used plates.
Claim 21 · checked 24 September 2026 · AI-assisted audit
Claim: The force is tiny and it is real
- Kind
- Experimental result. What an experiment or trial found, under its own conditions. A result in animals, cells or a simulation is not a result in people.
- Review
- Source checked. The cited passage was read, and it says this.
Supports
Measurement of the Casimir Force between Parallel Metallic Surfacesintroduction, third paragraph; equation 4 and following
Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Physical systems · Experiment
The source reads: this Letter we report on the measurement of the Casimir force ... parallel conducting ... The value obtained agrees with the expected value of KC first evaluated by Casimir
Supports
Measurement of the Casimir Force between Parallel Metallic Surfacesabstract
Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Physical systems · Experiment
The source reads: the related force coefficient was determined at ... 15% precision level.
Later work looked for
Crossref, 2003 on, "Casimir force parallel plates measurement": proposed sub-micron parallel-plate set-ups (2010, 2011) but nothing that replaces Bressi and others 2002 as the parallel-plate measurement; sphere and plate measurements reached about 1 per cent (as Bressi and others and Jaffe report). Nothing that changes the claim.
Claim 22 · checked 24 September 2026 · AI-assisted audit
Claim: and at nanometre separations it is strong enough to move the parts of a micromachine.
- Kind
- Experimental result. What an experiment or trial found, under its own conditions. A result in animals, cells or a simulation is not a result in people.
- Review
- Partly checked. Only part of the source could be read. What was not read is listed.
Supports
Quantum Mechanical Actuation of Microelectromechanical Systems by the Casimir Forceabstract (Europe PMC)
Cited · Link answered, 19 October 2026 · Abstract only, 24 September 2026 · Physical systems · Experiment
The source reads: Attraction between a polysilicon plate and a spherical metallic surface results in a torque that rotates the plate about two thin torsional rods ... quantum electrodynamical effects play a significant role in such microelectromechanical systems when the separation between components is in the nanometer range.
Supports
The Casimir force between real materials: Experiment and theorysection IV.C.2, Micromechanical devices actuated by the Casimir force
Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Review of the field
The source reads: the Casimir force, acting on the plate, tilted it about its central axis towards the sphere. Thus, vacuum oscillations of the electromagnetic field led to the mechanical motion of the plate demonstrating the first micromechanical device driven by the Casimir force.
What this does not establish
Chan and others 2001 was read as the abstract only, which gives the nanometre range; the motion of the plate is confirmed in the 2009 review, read in full. The device was a plate opposite a sphere, and it tilted.
Later work looked for
Crossref, 2003 on, "Casimir force parallel plates measurement": proposed sub-micron parallel-plate set-ups (2010, 2011) but nothing that replaces Bressi and others 2002 as the parallel-plate measurement; sphere and plate measurements reached about 1 per cent (as Bressi and others and Jaffe report). Nothing that changes the claim.
Claim 23 · checked 24 September 2026 · AI-assisted audit
Particles are excitations rather than things
Claim: Particles are excitations rather than things
- Kind
- This page’s reading. A judgement the page makes from the evidence. Others read it differently.
- Review
- A judgement, not a fact. Reviewed for whether it is fairly put and follows from the checked claims. No source can confirm it.
The quanta reading of quantum field theory, which the Stanford Encyclopedia entry attributes to Teller (1995).
Supports
Quantum Field Theorysection 5.1, on Teller (1995)
Cited · Link answered, 19 October 2026 · The cited passage was read, 24 September 2026 · Reference work
The source reads: The degree of excitation of a certain mode of the underlying field determines the number of objects, i.e., the particles in the sense of quanta.
Qualifies
Quantum Field Theorysection 5.1
Cited · Link answered, 19 October 2026 · The cited passage was read, 24 September 2026
The source reads: Teller has been criticized for drawing unduly far-reaching ontological conclusions from one particular representation
Supports
Quantum Field Theorysection 5.5
Cited · Link answered, 19 October 2026 · The cited passage was read, 24 September 2026 · Reference work
The source reads: it is controversial whether the two most prominent examples, namely the Unruh effect and Haag’s theorem, really do cause the contended problems in the first place.
Other readings
The entry reports criticism of that reading and argues that the field interpretation has troubles of its own; the page takes the quanta reading as its heading.
Claim 24 · checked 24 September 2026 · AI-assisted audit
Claim: In quantum field theory a particle is a quantum of excitation of a field that exists everywhere.
- Kind
- What a model says. What a theory or model predicts or describes, which is not the same as what has been observed.
- Review
- Source checked. The cited passage was read, and it says this.
Supports
Quantum Field Theorysection 5.1, on Teller (1995)
Cited · Link answered, 19 October 2026 · The cited passage was read, 24 September 2026 · Reference work
The source reads: The degree of excitation of a certain mode of the underlying field determines the number of objects, i.e., the particles in the sense of quanta.
Supports
Quantum Field Theorysection 5.5
Cited · Link answered, 19 October 2026 · The cited passage was read, 24 September 2026 · Reference work
The source reads: a field is not a localized entity
Other readings
Whether quanta are particles in any full sense is disputed; the Stanford Encyclopedia entry reports that the counting of quanta is only one feature of particles.
Later work looked for
How the method or model works; not a finding later work revises.
Claim 25 · checked 24 September 2026 · AI-assisted audit
Claim: On the theory, an accelerating observer sees a thermal bath of particles where an inertial observer sees vacuum.
- Kind
- What a model says. What a theory or model predicts or describes, which is not the same as what has been observed.
- Review
- Source checked. The cited passage was read, and it says this.
Supports
Quantum Field Theorysection 4.5
Cited · Link answered, 19 October 2026 · The cited passage was read, 24 September 2026 · Reference work
The source reads: a uniformly accelerated observer in a Minkowski vacuum should detect a thermal bath of particles, the so-called Rindler quanta
Context
Notes on black-hole evaporationabstract (INSPIRE record)
Cited · Link answered, 19 October 2026 · Abstract only, 24 September 2026
The source reads: an accelerated detector even in flat spacetime will detect particles in the vacuum.
The original paper, read only as its abstract; the thermal spectrum is carried by the encyclopedia entry.
What this does not establish
A prediction of the theory. It has not been observed directly.
Later work looked for
Crossref, 2020 on, "Unruh effect observation experiment": simulations, proposals and analyses of the limits to observation; no direct detection, so "on the theory" stands.
Corrected
24 September 2026. Previously: “The number of particles is not an absolute: an accelerating observer, on the theory, sees a thermal bath of particles where an inertial observer sees vacuum.” The conclusion drawn from the effect is moved to the next paragraph and attributed, because it is disputed.
Claim 26 · checked 24 September 2026 · AI-assisted audit
Claim: Many take that to mean the number of particles is not an absolute, so that how many are in a region need not have an observer-independent answer.
- Kind
- What scholars argue. A report of what specialists argue, or where they disagree.
- Review
- Source checked. The cited passage was read, and it says this.
Supports
Quantum Field Theorysection 5.5
Cited · Link answered, 19 October 2026 · The cited passage was read, 24 September 2026 · Reference work
The source reads: many take the Unruh effect to indicate that the particle number is observer or context dependent.
Corrected
24 September 2026. Previously: “That reframes what a particle is, and it is the reason questions about how many particles are in a region do not always have an observer-independent answer.” Stated as settled; the Stanford Encyclopedia entry reports it as what many take the Unruh effect to show, and reports those who deny it.
Claim 27 · checked 24 September 2026 · AI-assisted audit
Claim: Others argue that the accelerating observer’s particles are not real, and philosophers of physics still dispute how much the effect shows.
- Kind
- What scholars argue. A report of what specialists argue, or where they disagree.
- Review
- Source checked. The cited passage was read, and it says this.
Supports
Quantum Field Theorysection 4.5
Cited · Link answered, 19 October 2026 · The cited passage was read, 24 September 2026 · Reference work
The source reads: Arageorgis, Earman and Ruetsche (2003) argue that Minkowski and Rindler (or Fulling) quantization do not constitute a satisfactory case ... Rindler quanta are not real
Supports
Quantum Field Theorysection 5.5
Cited · Link answered, 19 October 2026 · The cited passage was read, 24 September 2026 · Reference work
The source reads: it is controversial whether the two most prominent examples, namely the Unruh effect and Haag’s theorem, really do cause the contended problems in the first place.
Corrected
24 September 2026. Previously: “” Added so that the disagreement the entry reports is on the page, with who holds each side.
Claim 28 · checked 24 September 2026 · AI-assisted audit
What it means
Claim: What it means
- Kind
- Framing. Signposting. It asserts nothing a source could check.
Claim: A theory that works to twelve decimal places
- Kind
- Experimental result. What an experiment or trial found, under its own conditions. A result in animals, cells or a simulation is not a result in people.
- Review
- Source checked. The cited passage was read, and it says this.
Supports
Measurement of the Electron Magnetic Momentabstract (arXiv)
Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Physical systems · Measurement
The source reads: tests the most precise prediction of the Standard Model (SM) to 1 part in 10¹²
Notation restored: LaTeX markup rendered and the superscript restored from the arXiv PDF as rendered, read 2026-09-24. The text as extracted reads: tests the most precise prediction of the Standard Model (SM) to $1$ part in $10^{12}$
Qualifies
Measurement of the Electron Magnetic Momentabstract (arXiv)
Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026
The source reads: The test would improve an order of magnitude if the uncertainty from discrepant measurements of the fine structure constant α is eliminated
Notation restored: LaTeX markup rendered from the arXiv PDF as rendered, read 2026-09-24. The text as extracted reads: The test would improve an order of magnitude if the uncertainty from discrepant measurements of the fine structure constant $α$ is eliminated
Supports
Measurement of the Electron Magnetic Momentfirst page, second column
Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Physical systems · Measurement
The source reads: In the most precise confrontation of theory and measurement, the SM prediction agrees to 1 part in 10¹²
Notation restored: The superscript, lost in PDF text extraction, restored from the arXiv PDF as rendered, read 2026-09-24. The text as extracted reads: In the most precise confrontation of theory and measurement, the SM prediction agrees to 1 part in 1012
Agreement to one part in 10¹² on a quantity of about 1.001 is agreement to about the twelfth decimal place.
What this does not establish
The twelve places are for one quantity, the electron’s magnetic moment, tested against the Standard Model; the test is limited by disagreeing measurements of the fine structure constant.
Later work looked for
Crossref, 2023 on, "electron magnetic moment measurement": Fan and others 2023 is the latest measurement found.
Claim 30 · checked 24 September 2026 · AI-assisted audit
Claim: and is wrong about the energy of empty space by as much as a hundred and twenty orders of magnitude.
- Kind
- What scholars argue. A report of what specialists argue, or where they disagree.
- Review
- Source checked. The cited passage was read, and it says this.
Supports
The cosmological constant problemsection I
Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Review of the field
The source reads: exceed observational limits ... some 120 orders of magnitude
Supports
Everything you always wanted to know about the cosmological constant problem (but were afraid to ask)section X.A, after equation 548
Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Review of the field
The source reads: the large mismatch between the theoretical expectation (516) and the above, observationally determined, number (548), something like 54 orders of magnitude (but much less than the 122 orders of magnitude often quoted in the literature)
What this does not establish
120 is the simplest estimate; Martin 2012 finds about 54 orders when the zero-point energy is properly renormalised.
Later work looked for
Crossref, 2018 on, "cosmological constant problem review", and Martin 2012 read in full: the problem is unsolved; Martin finds a properly renormalised mismatch of about 54 orders rather than the often quoted 120 or so, which the page already covers with "dozens".
Corrected
24 September 2026. Previously: “A theory that works to twelve decimal places, and is wrong about the energy of empty space by a hundred and twenty orders of magnitude.” 120 is the crudest estimate; the page itself says careful treatments give dozens, and Martin 2012 gets about 54.
Claim 31 · checked 24 September 2026 · AI-assisted audit
A prediction off by dozens of orders of magnitude
Claim: A prediction off by dozens of orders of magnitude
- Kind
- This page’s reading. A judgement the page makes from the evidence. Others read it differently.
- Review
- A judgement, not a fact. Reviewed for whether it is fairly put and follows from the checked claims. No source can confirm it.
The page’s own ranking, from the size of the mismatch in claims 36 and 37. No cited source ranks it against every other prediction.
Corrected
24 September 2026. Previously: “The worst prediction in physics” No source ranks the gap against every other prediction in physics; the passage beneath gives the sizes the sources give (about 120 orders on the simplest estimate, dozens on careful ones), and the heading now says that.
Claim 32 · checked 24 September 2026 · AI-assisted audit
Claim: Summing the zero-point energies of the fields gives a vacuum energy density.
- Kind
- What a model says. What a theory or model predicts or describes, which is not the same as what has been observed.
- Review
- Source checked. The cited passage was read, and it says this.
Supports
The cosmological constant problemsection III
Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Review of the field
The source reads: summing the zero-point energies of all normal modes of some field of mass m up to a wave number cutoff
Supports
Casimir effect and the quantum vacuumintroduction, first paragraph
Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026
The source reads: In quantum field theory as usually formulated, the zero point fluctuations of the fields contribute to the energy of the vacuum.
What this does not establish
The sum has no finite value without a cutoff, and the result depends on where the cutoff is put; Weinberg 1989 takes the Planck scale for the largest figure.
Later work looked for
How the method or model works; not a finding later work revises.
Claim 33 · checked 24 September 2026 · AI-assisted audit
Claim: Gravity responds to energy, so that density should curve spacetime
- Kind
- What a model says. What a theory or model predicts or describes, which is not the same as what has been observed.
- Review
- Source checked. The cited passage was read, and it says this.
Supports
Casimir effect and the quantum vacuumintroduction, first paragraph
Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026
The source reads: Nevertheless, all energy gravitates, and therefore the energy density of the vacuum ... appears on the right hand side of Einstein’s equations ... It is equivalent to adding a cosmological term
Qualifies
Everything you always wanted to know about the cosmological constant problem (but were afraid to ask)section XII.B.2, "Finally"
Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026
The source reads: fluctuations do exist but have non-standard gravitational properties, i.e. that they abnormally weigh.
What this does not establish
That the vacuum’s energy gravitates like any other is the standard assumption; Martin 2012 notes zero-point fluctuations might have non-standard gravitational properties, and no laboratory experiment tests it.
Later work looked for
How the method or model works; not a finding later work revises.
Claim 34 · checked 24 September 2026 · AI-assisted audit
Claim: and it corresponds to the cosmological constant that is measured from the expansion of the universe.
- Kind
- What a model says. What a theory or model predicts or describes, which is not the same as what has been observed.
- Review
- Source checked. The cited passage was read, and it says this.
Supports
Casimir effect and the quantum vacuumintroduction, first paragraph
Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026
The source reads: Nevertheless, all energy gravitates, and therefore the energy density of the vacuum ... appears on the right hand side of Einstein’s equations ... It is equivalent to adding a cosmological term
Supports
Casimir effect and the quantum vacuumintroduction, second paragraph
Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Astronomical observation
The source reads: A small, positive cosmological term is now required ... for the observation that the expansion of the Universe is accelerating.
Qualifies
DESI DR2 results. II. Measurements of baryon acoustic oscillations and cosmological constraintsabstract (arXiv:2503.14738v3 PDF)
Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026
The source reads: The results are well described by a flat ΛCDM model ... Unless there is an unknown systematic error associated with one or more datasets
What this does not establish
Whether the measured quantity is a constant is now tested: DESI DR2 prefers dark energy that changes with time (claim 47).
Later work looked for
Crossref, 2024 on, DESI: the acceleration stands; DESI DR2 BAO prefers dark energy that evolves over a constant at 2.8 to 4.2 sigma depending on the supernova sample. The page now says constancy is under test.
Claim 35 · checked 24 September 2026 · AI-assisted audit
Claim: The measured value is smaller than the simplest estimate by something like 120 orders of magnitude.
- Kind
- What scholars argue. A report of what specialists argue, or where they disagree.
- Review
- Source checked. The cited passage was read, and it says this.
Supports
The cosmological constant problemsection I
Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Review of the field
The source reads: exceed observational limits ... some 120 orders of magnitude
Supports
The cosmological constant problemsection III
Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Review of the field
The source reads: the two terms here must cancel to better than 118 decimal places. Even if we only worry about zero-point energies in quantum chromo dynamics
Supports
Everything you always wanted to know about the cosmological constant problem (but were afraid to ask)section X.A, after equation 548
Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Review of the field
The source reads: the large mismatch between the theoretical expectation (516) and the above, observationally determined, number (548), something like 54 orders of magnitude (but much less than the 122 orders of magnitude often quoted in the literature)
What this does not establish
In 1989 Weinberg compared the estimate with an observational limit, not a measured value; Martin 2012 gives about 122 orders as the figure often quoted.
Later work looked for
Crossref, 2018 on, "cosmological constant problem review", and Martin 2012 read in full: the problem is unsolved; Martin finds a properly renormalised mismatch of about 54 orders rather than the often quoted 120 or so, which the page already covers with "dozens".
Claim 36 · checked 24 September 2026 · AI-assisted audit
Claim: Even careful treatments leave a discrepancy of dozens of orders of magnitude.
- Kind
- What scholars argue. A report of what specialists argue, or where they disagree.
- Review
- Source checked. The cited passage was read, and it says this.
Supports
Everything you always wanted to know about the cosmological constant problem (but were afraid to ask)section X.A, after equation 548
Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Review of the field
The source reads: the large mismatch between the theoretical expectation (516) and the above, observationally determined, number (548), something like 54 orders of magnitude (but much less than the 122 orders of magnitude often quoted in the literature)
Supports
The cosmological constant problemsection III
Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Review of the field
The source reads: to cancel this term to about 41 decimal places
Later work looked for
Crossref, 2018 on, "cosmological constant problem review", and Martin 2012 read in full: the problem is unsolved; Martin finds a properly renormalised mismatch of about 54 orders rather than the often quoted 120 or so, which the page already covers with "dozens".
Claim 37 · checked 24 September 2026 · AI-assisted audit
Claim: This is not a small residual.
- Kind
- This page’s reading. A judgement the page makes from the evidence. Others read it differently.
- Review
- A judgement, not a fact. Reviewed for whether it is fairly put and follows from the checked claims. No source can confirm it.
Follows from claims 36 and 37.
Claim 38 · checked 24 September 2026 · AI-assisted audit
Claim: Steven Weinberg called it a “veritable crisis”
- Kind
- What scholars argue. A report of what specialists argue, or where they disagree.
- Review
- Source checked. The cited passage was read, and it says this.
Supports
The cosmological constant problemsection I
Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Review of the field
The source reads: interest is increasingly centered on one veritable crisis: theoretical expectations for the cosmological con- stant exceed observational limits
Corrected
24 September 2026. Previously: “It is the largest mismatch between theory and observation anywhere in physics” A universal the sources do not make: none ranks the gap against every mismatch in physics. Replaced with Weinberg's own words for it.
Claim 39 · checked 24 September 2026 · AI-assisted audit
Claim: and it has been open since the problem was recognised.
- Kind
- Open question. Something the page says is not known.
- Review
- Presented as open. The page says this is unresolved, and the review found that it is.
Supports
Everything you always wanted to know about the cosmological constant problem (but were afraid to ask)section X.A, after equation 548
Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Review of the field
The source reads: Something is clearly wrong but, as will be discussed, it is difficult to identify where the mistake is.
Supports
The cosmological constant problemabstract
Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Review of the field
The source reads: Astronomical observations indicate that the cosmological constant is many orders of magnitude smaller than estimated in modern theories of elementary particles ... five different approaches to its solution are described.
Later work looked for
Crossref, 2018 on, "cosmological constant problem review", and Martin 2012 read in full: the problem is unsolved; Martin finds a properly renormalised mismatch of about 54 orders rather than the often quoted 120 or so, which the page already covers with "dozens".
Claim 40 · checked 24 September 2026 · AI-assisted audit
Claim: What the vacuum does and does not explain
- Kind
- Framing. Signposting. It asserts nothing a source could check.
Claim: Plates in vacuum attract at sub-micrometre separations.
- Kind
- Experimental result. What an experiment or trial found, under its own conditions. A result in animals, cells or a simulation is not a result in people.
- Review
- Source checked. The cited passage was read, and it says this.
Supports
Measurement of the Casimir Force between Parallel Metallic Surfacesintroduction, third paragraph; equation 4 and following
Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Physical systems · Experiment
The source reads: this Letter we report on the measurement of the Casimir force ... parallel conducting ... The value obtained agrees with the expected value of KC first evaluated by Casimir
Supports
Measurement of the Casimir Force between Parallel Metallic Surfacesabstract
Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Physical systems · Experiment
The source reads: the related force coefficient was determined at ... 15% precision level.
Context
Quantum Mechanical Actuation of Microelectromechanical Systems by the Casimir Forceabstract (Europe PMC)
Cited · Link answered, 19 October 2026 · Abstract only, 24 September 2026 · Physical systems · Experiment
The source reads: Attraction between a polysilicon plate and a spherical metallic surface results in a torque that rotates the plate about two thin torsional rods ... quantum electrodynamical effects play a significant role in such microelectromechanical systems when the separation between components is in the nanometer range.
Read as the abstract only: a plate and a sphere at nanometre separations.
What this does not establish
The parallel-plate measurement reached down to 0.5 micrometres; the nanometre results are for a plate and a sphere.
Later work looked for
Crossref, 2003 on, "Casimir force parallel plates measurement": proposed sub-micron parallel-plate set-ups (2010, 2011) but nothing that replaces Bressi and others 2002 as the parallel-plate measurement; sphere and plate measurements reached about 1 per cent (as Bressi and others and Jaffe report). Nothing that changes the claim.
Claim 42 · checked 24 September 2026 · AI-assisted audit
Claim: The vacuum has structure with measurable consequences.
- Kind
- What a model says. What a theory or model predicts or describes, which is not the same as what has been observed.
- Review
- Source checked. The cited passage was read, and it says this.
Supports
Everything you always wanted to know about the cosmological constant problem (but were afraid to ask)section XII.B.2, "Thirdly"
Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Review of the field
The source reads: the Casimir Force has been observed in the laboratory and this is usually taken as another evidence in favor of the existence of the zero-point fluctuations.
Supports
Everything you always wanted to know about the cosmological constant problem (but were afraid to ask)section XII.B.2, "Fourthly"
Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Review of the field
The source reads: are nevertheless necessary to quantum field theory even if the above remark should lead us to tone down the claim that they have been seen in the laboratory
What this does not establish
Whether the vacuum is where the force comes from is disputed: Jaffe 2005 derives the same force from the charges in the plates without reference to the vacuum, and Martin 2012 holds that zero-point fluctuations are still needed in quantum field theory. See claims 60 and 61.
Later work looked for
How the method or model works; not a finding later work revises.
Claim 43 · checked 24 September 2026 · AI-assisted audit
Claim: This part works.
- Kind
- This page’s reading. A judgement the page makes from the evidence. Others read it differently.
- Review
- A judgement, not a fact. Reviewed for whether it is fairly put and follows from the checked claims. No source can confirm it.
Follows from the agreement between Casimir’s calculation and the measurements in claims 20 and 21.
Claim 44 · checked 24 September 2026 · AI-assisted audit
Claim: The expansion of the universe is accelerating.
- Kind
- Observation. Something measured or seen, as the named source reports it.
- Review
- Source checked. The cited passage was read, and it says this.
Supports
Casimir effect and the quantum vacuumintroduction, second paragraph
Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Astronomical observation
The source reads: A small, positive cosmological term is now required ... for the observation that the expansion of the Universe is accelerating.
Supports
Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Review of the field
The source reads: from the discovery that the expansion of the universe is accelerated
Supports
Everything you always wanted to know about the cosmological constant problem (but were afraid to ask)reference 24
Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026
The source reads: A. G. Riess et al. (Supernova Search Team), Astron. J. 116, 1009 (1998)
Later work looked for
Crossref, 2024 on, DESI: the acceleration stands; DESI DR2 BAO prefers dark energy that evolves over a constant at 2.8 to 4.2 sigma depending on the supernova sample. The page now says constancy is under test.
Claim 45 · checked 24 September 2026 · AI-assisted audit
Claim: A small positive energy density of space, now measured.
- Kind
- What a model says. What a theory or model predicts or describes, which is not the same as what has been observed.
- Review
- Source checked. The cited passage was read, and it says this.
Supports
Casimir effect and the quantum vacuumintroduction, second paragraph
Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Astronomical observation
The source reads: A small, positive cosmological term is now required ... for the observation that the expansion of the Universe is accelerating.
Supports
Casimir effect and the quantum vacuumintroduction, first paragraph
Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026
The source reads: Nevertheless, all energy gravitates, and therefore the energy density of the vacuum ... appears on the right hand side of Einstein’s equations ... It is equivalent to adding a cosmological term
What this does not establish
The acceleration is observed; that it is an energy density of space is the standard reading (the cosmological constant). Jaffe 2005 gives the measured value as (2.14 ± 0.13 × 10⁻³ eV)⁴.
Later work looked for
Crossref, 2024 on, DESI: the acceleration stands; DESI DR2 BAO prefers dark energy that evolves over a constant at 2.8 to 4.2 sigma depending on the supernova sample. The page now says constancy is under test.
Corrected
24 September 2026. Previously: “A small positive energy density of space, measured precisely.” The measured value the page cites (Jaffe 2005) carries a 6 per cent uncertainty in its fourth root, which "precisely" overstated; and DESI DR2 (2025) prefers dark energy that evolves, so whether the density is constant is now open.
Claim 46 · checked 24 September 2026 · AI-assisted audit
Claim: Whether it is constant is under test.
- Kind
- What scholars argue. A report of what specialists argue, or where they disagree.
- Review
- Source checked. The cited passage was read, and it says this.
Supports
DESI DR2 results. II. Measurements of baryon acoustic oscillations and cosmological constraintsabstract (arXiv:2503.14738v3 PDF)
Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Astronomical observation · Measurement
The source reads: This tension is alleviated by dark energy with a time-evolving equation of state ... the preference for a dynamical dark energy model over ΛCDM ranges from 2.8 − 4.2σ depending on which SNe sample is used.
Qualifies
DESI DR2 results. II. Measurements of baryon acoustic oscillations and cosmological constraintsabstract (arXiv:2503.14738v3 PDF)
Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026
The source reads: The results are well described by a flat ΛCDM model ... Unless there is an unknown systematic error associated with one or more datasets
Supports
DESI DR2 results. II. Measurements of baryon acoustic oscillations and cosmological constraintssection IX, Conclusions
Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Astronomical observation · Measurement
The source reads: The evidence for a departure from ΛCDM in the form of evolving dark energy has increased with the DR2 BAO data.
What this does not establish
The preference for evolving dark energy is 2.8 to 4.2 sigma depending on the supernova sample, below the usual threshold for a discovery, and the collaboration notes a possible unknown systematic error.
Later work looked for
Crossref, 2024 on, DESI: the acceleration stands; DESI DR2 BAO prefers dark energy that evolves over a constant at 2.8 to 4.2 sigma depending on the supernova sample. The page now says constancy is under test.
Claim 47 · checked 24 September 2026 · AI-assisted audit
Claim: Field theory’s estimate of that density.
- Kind
- Framing. Signposting. It asserts nothing a source could check.
Claim: Too large by dozens of orders of magnitude at best.
- Kind
- What scholars argue. A report of what specialists argue, or where they disagree.
- Review
- Source checked. The cited passage was read, and it says this.
Supports
Everything you always wanted to know about the cosmological constant problem (but were afraid to ask)section X.A, after equation 548
Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Review of the field
The source reads: the large mismatch between the theoretical expectation (516) and the above, observationally determined, number (548), something like 54 orders of magnitude (but much less than the 122 orders of magnitude often quoted in the literature)
Supports
The cosmological constant problemsection III
Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Review of the field
The source reads: to cancel this term to about 41 decimal places
Later work looked for
Crossref, 2018 on, "cosmological constant problem review", and Martin 2012 read in full: the problem is unsolved; Martin finds a properly renormalised mismatch of about 54 orders rather than the often quoted 120 or so, which the page already covers with "dozens".
Claim 49 · checked 24 September 2026 · AI-assisted audit
Claim: Something is badly wrong and nobody knows what.
- Kind
- Open question. Something the page says is not known.
- Review
- Presented as open. The page says this is unresolved, and the review found that it is.
Supports
Everything you always wanted to know about the cosmological constant problem (but were afraid to ask)section X.A, after equation 548
Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Review of the field
The source reads: Something is clearly wrong but, as will be discussed, it is difficult to identify where the mistake is.
Later work looked for
Crossref, 2018 on, "cosmological constant problem review", and Martin 2012 read in full: the problem is unsolved; Martin finds a properly renormalised mismatch of about 54 orders rather than the often quoted 120 or so, which the page already covers with "dozens".
Claim 50 · checked 24 September 2026 · AI-assisted audit
How the problem was stated
Claim: How the problem was stated
- Kind
- Framing. Signposting. It asserts nothing a source could check.
Claim: The standard statement of it is
- Kind
- This page’s reading. A judgement the page makes from the evidence. Others read it differently.
- Review
- A judgement, not a fact. Reviewed for whether it is fairly put and follows from the checked claims. No source can confirm it.
The page’s judgement. Jaffe 2005 and Martin 2012 both cite Weinberg’s review for the problem.
Claim 52 · checked 24 September 2026 · AI-assisted audit
Claim: a 1989 review by Steven Weinberg
- Kind
- Historical claim. A statement about the past that historical evidence can test.
- Review
- Source checked. The cited passage was read, and it says this.
Supports
The cosmological constant problempage footer
Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026
The source reads: Reviews of Modern Physics, Vol. 61, No. 1, January 1989
Claim 53 · checked 24 September 2026 · AI-assisted audit
Claim: written before the acceleration of the expansion was discovered and before anyone knew the answer was small and not zero.
- Kind
- Historical claim. A statement about the past that historical evidence can test.
- Review
- Source checked. The cited passage was read, and it says this.
Supports
The cosmological constant problempage footer
Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026
The source reads: Reviews of Modern Physics, Vol. 61, No. 1, January 1989
Supports
The cosmological constant problemsection III
Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026
The source reads: simply assumed that for some unknown reason this quantity was zero
Supports
Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Review of the field
The source reads: from the discovery that the expansion of the universe is accelerated
Supports
Everything you always wanted to know about the cosmological constant problem (but were afraid to ask)reference 24
Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026
The source reads: A. G. Riess et al. (Supernova Search Team), Astron. J. 116, 1009 (1998)
Claim 54 · checked 24 September 2026 · AI-assisted audit
Claim: It works through the contributions to the vacuum energy from each part of the Standard Model, shows that they do not cancel for any reason anybody can find, and surveys the attempts to explain why the total is so much smaller than any of its parts.
- Kind
- What scholars argue. A report of what specialists argue, or where they disagree.
- Review
- Source checked. The cited passage was read, and it says this.
The review treats zero-point energies, quantum chromodynamics and the electroweak scalar potential in turn, then five approaches to a solution.
Supports
The cosmological constant problemsection III
Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Review of the field
The source reads: the two terms here must cancel to better than 118 decimal places. Even if we only worry about zero-point energies in quantum chromo dynamics
Supports
The cosmological constant problemend of section IV
Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026
The source reads: of no such symmetry (aside from the unrealistic example of unbroken supersymmetry) that could keep the effective cosmological constant sufficiently small
Supports
The cosmological constant problemabstract
Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Review of the field
The source reads: Astronomical observations indicate that the cosmological constant is many orders of magnitude smaller than estimated in modern theories of elementary particles ... five different approaches to its solution are described.
Claim 55 · checked 24 September 2026 · AI-assisted audit
Claim: The discovery of a small positive value nine years later
- Kind
- Historical claim. A statement about the past that historical evidence can test.
- Review
- Source checked. The cited passage was read, and it says this.
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Everything you always wanted to know about the cosmological constant problem (but were afraid to ask)reference 24
Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026
The source reads: A. G. Riess et al. (Supernova Search Team), Astron. J. 116, 1009 (1998)
Supports
Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Review of the field
The source reads: from the discovery that the expansion of the universe is accelerated
Supports
The cosmological constant problempage footer
Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026
The source reads: Reviews of Modern Physics, Vol. 61, No. 1, January 1989
Claim 56 · checked 24 September 2026 · AI-assisted audit
Claim: made the problem harder rather than easier: a zero might have been explained by a symmetry, and a tiny non-zero number has to be explained by something that knows how tiny to be.
- Kind
- This page’s reading. A judgement the page makes from the evidence. Others read it differently.
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- A judgement, not a fact. Reviewed for whether it is fairly put and follows from the checked claims. No source can confirm it.
Follows from Weinberg 1989, where theorists assumed the total was zero and looked for a symmetry to guarantee it, and from Martin 2012, where boson and fermion contributions can be made to cancel exactly.
Supports
The cosmological constant problemsection III
Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026
The source reads: simply assumed that for some unknown reason this quantity was zero
Supports
The cosmological constant problemend of section IV
Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026
The source reads: of no such symmetry (aside from the unrealistic example of unbroken supersymmetry) that could keep the effective cosmological constant sufficiently small
Context
Everything you always wanted to know about the cosmological constant problem (but were afraid to ask)section IV (supersymmetry, "Motivation")
Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026
The source reads: the two contributions are equal in absolute value such that the final result is exactly zero.
Claim 57 · checked 24 September 2026 · AI-assisted audit
Whether the Casimir force proves the rest
Claim: Whether the Casimir force proves the rest
- Kind
- Framing. Signposting. It asserts nothing a source could check.
Claim: The Casimir effect is often presented as a direct demonstration of vacuum energy.
- Kind
- What scholars argue. A report of what specialists argue, or where they disagree.
- Review
- Source checked. The cited passage was read, and it says this.
Supports
Casimir effect and the quantum vacuumabstract; introduction
Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026
The source reads: In discussions of the cosmological constant, the Casimir ... is often invoked as decisive evidence that the zero point energies of quantum fields are ... theorists often point to the Casimir effect
Supports
The cosmological constant problemsection III
Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026
The source reads: despite the demonstration in the Casimir effect of the reality of zero-point energies
Supports
Everything you always wanted to know about the cosmological constant problem (but were afraid to ask)section XII.B.2, "Thirdly"
Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Review of the field
The source reads: the Casimir Force has been observed in the laboratory and this is usually taken as another evidence in favor of the existence of the zero-point fluctuations.
Claim 59 · checked 24 September 2026 · AI-assisted audit
Claim: It can also be derived as a force between the charges in the plates, mediated in a way that never mentions the vacuum.
- Kind
- What scholars argue. A report of what specialists argue, or where they disagree.
- Review
- Source checked. The cited passage was read, and it says this.
The derivation goes back to Schwinger and to Schwinger, DeRaad and Milton; Jaffe 2005 sets it out and Martin 2012 accepts it.
Supports
Casimir effect and the quantum vacuumconclusion; introduction
Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026
The source reads: Casimir forces can be calculated without reference to the vacuum ... the Casimir force originates in the forces between charged particles in the metal plates.
Supports
Casimir effect and the quantum vacuumsection on calculation without vacuum energies
Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026
The source reads: it is nevertheless possible to derive his result without any reference to zero point fluctuations or even to the vacuum
Supports
Everything you always wanted to know about the cosmological constant problem (but were afraid to ask)section XII.B.2, "Fourthly"
Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Review of the field
The source reads: It is indeed possible to derive the expression of the Casimir force without referring at all to zero point fluctuations
Claim 60 · checked 24 September 2026 · AI-assisted audit
Claim: The two calculations agree, so the measurement does not by itself settle which description is fundamental.
- Kind
- Disputed. A contested point, where the page reports a side or the disagreement.
- Review
- A judgement, not a fact. Reviewed for whether it is fairly put and follows from the checked claims. No source can confirm it.
Supports
Casimir effect and the quantum vacuumconclusion
Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026
The source reads: Still, no known phenomenon, including the Casimir effect, demonstrates that zero point energies are “real”.
Supports
Everything you always wanted to know about the cosmological constant problem (but were afraid to ask)section XII.B.2, "Fourthly"
Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Review of the field
The source reads: are nevertheless necessary to quantum field theory even if the above remark should lead us to tone down the claim that they have been seen in the laboratory
Qualifies
Casimir effect and the quantum vacuumconclusion
Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026
The source reads: Perhaps there is a consistent formulation of relativistic quantum mechanics in which zero point ... never appear. I doubt it.
What this does not establish
The agreement is in the limit of perfect conductors; for real metals the charge-based calculation depends on the material (Jaffe 2005).
Other readings
Jaffe 2005 argues that no known phenomenon, the Casimir effect included, shows zero-point energies are real, though he doubts they can be avoided. Martin 2012 accepts the claim of a laboratory sighting should be toned down but holds that zero-point fluctuations are still necessary to quantum field theory.
Claim 61 · checked 24 September 2026 · AI-assisted audit
Claim: That matters when the effect is used as evidence in arguments about the cosmological constant.
- Kind
- What scholars argue. A report of what specialists argue, or where they disagree.
- Review
- Source checked. The cited passage was read, and it says this.
Supports
Casimir effect and the quantum vacuumabstract; introduction
Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026
The source reads: In discussions of the cosmological constant, the Casimir ... is often invoked as decisive evidence that the zero point energies of quantum fields are ... theorists often point to the Casimir effect
Supports
Everything you always wanted to know about the cosmological constant problem (but were afraid to ask)section XII.B.2, "Finally"
Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Review of the field
The source reads: they do not say anything with regards to their gravitational properties
Claim 62 · checked 24 September 2026 · AI-assisted audit
What was read
- Demonstration of the Casimir Force in the 0.6 to 6 micrometre RangeLamoreaux, Physical Review Letters · Abstract as held by INSPIRE; the closed PRL and its erratum (Phys. Rev. Lett. 81, 5475, 1998) were not readAbstract only, 24 September 2026 · Copyright; quoted briefly
- Quantum Mechanical Actuation of Microelectromechanical Systems by the Casimir ForceChan and others, Science · Abstract in Europe PMC (PMID 11239149)Abstract only, 24 September 2026 · Copyright; quoted briefly
- Notes on black-hole evaporationUnruh, Physical Review D · Abstract as held by INSPIREAbstract only, 24 September 2026 · Copyright; quoted briefly
- The cosmological constant problemWeinberg, Reviews of Modern Physics · Open repository copy, University of Texas (hdl.handle.net/2152/61094), scanned textRead in full, 24 September 2026 · Copyright; quoted brieflyThe scanned text has OCR errors; excerpts skip garbled runs with an ellipsis.
- Casimir effect and the quantum vacuumJaffe, Physical Review D · arXiv:hep-th/0503158v1 (21 March 2005), the preprint of Phys. Rev. D 72, 021301Read in full, 24 September 2026 · Copyright; quoted briefly
- Measurement of the Casimir Force between Parallel Metallic SurfacesBressi, Carugno, Onofrio and Ruoso, Physical Review Letters · arXiv:quant-ph/0203002v1 (1 March 2002)Read in full, 24 September 2026 · Copyright; quoted brieflyPDF text extraction splits some words; one excerpt keeps that spacing so it can be matched.
- Everything you always wanted to know about the cosmological constant problem (but were afraid to ask)Martin, Comptes Rendus Physique · arXiv:1205.3365; read abstract, introduction, sections X.A and XII.B, and searched the restRead in full, 24 September 2026 · Copyright; quoted briefly
- Quantum Field TheoryStanford Encyclopedia of Philosophy · Kuhlmann, Stanford Encyclopedia of Philosophy, substantive revision 9 September 2026; read sections 4.5, 5.1 and 5.5The cited passage was read, 24 September 2026 · Copyright; quoted briefly
- Measurement of the Electron Magnetic MomentFan, Myers, Sukra and Gabrielse, Physical Review Letters · arXiv:2209.13084, PDF dated 8 December 2022, read as text (pdftotext) and checked against the rendered PDFRead in full, 24 September 2026 · arXiv non-exclusive distribution licence; copyright APS; quoted brieflyThe abstract excerpt keeps the arXiv abstract’s LaTeX markup as served, and the PDF text loses superscripts (“1012” for 10¹²); both carry a display with the notation restored.
- The Casimir force between real materials: Experiment and theoryKlimchitskaya, Mohideen and Mostepanenko, Reviews of Modern Physics · arXiv:0902.4022, the preprint of Rev. Mod. Phys. 81, 1827 (2009), PDF read as text (pdftotext); sections IV.A and IV.C read, the rest searchedRead in full, 24 September 2026 · arXiv non-exclusive distribution licence; copyright APS; quoted brieflyA review by one of the groups that measures the force. Its account of Lamoreaux 1997 is used where the closed paper could not be read.
- DESI DR2 results. II. Measurements of baryon acoustic oscillations and cosmological constraintsDESI Collaboration, Physical Review D · arXiv:2503.14738v3 (9 October 2025), PDF read as text (pdftotext); abstract and Conclusions read, the rest searchedRead in full, 24 September 2026 · CC BY 4.0