Fulvio Melia | The University of Arizona (original) (raw)
Papers by Fulvio Melia
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American Astronomical Society Meeting Abstracts, Dec 1, 1999
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Monthly Notices of the Royal Astronomical Society, Nov 18, 2011
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arXiv (Cornell University), Mar 2, 2009
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Zeitschrift für Naturforschung A
The evidence in favor of a Universe expanding at a constant rate, in contrast to the various epis... more The evidence in favor of a Universe expanding at a constant rate, in contrast to the various episodes of deceleration and acceleration expected in the standard model, has been accumulating for over a decade now. In recent years, this inference has been strengthened by a study of the Friedmann–Lemaître–Robertson–Walker (FLRW) metric in relation to Einstein’s principle of equivalence. This earlier work concluded that the choice of lapse function g tt = 1 characterizing the FLRW solution to Einstein’s equations is inconsistent with any kind of accelerated cosmic expansion. In this paper, we demonstrate and confirm this important result by directly testing the self-consistency of four well-known FLRW cosmologies. These include the Milne universe, de Sitter space, the Lanczos universe, and the R h = ct model. We show that only the constantly expanding models (Milne and R h = ct) are consistent with the principle of equivalence, while de Sitter and Lanczos fail the test. We discuss some o...
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Monthly Notices of the Royal Astronomical Society: Letters, 2023
The so-called ‘impossibly early galaxy’ problem, first identified via the Hubble Space Telescope’... more The so-called ‘impossibly early galaxy’ problem, first identified via the Hubble Space Telescope’s observation of galaxies at redshifts z > 10, appears to have been exacerbated by the more recent James Webb Space Telescope (JWST) discovery of galaxy candidates at even higher redshifts (z ∼ 17) which, however, are yet to be confirmed spectroscopically. These candidates would have emerged only ∼230 million years after the big bang in the context of ΛCDM, requiring a more rapid star formation in the earliest galaxies than appears to be permitted by simulations adopting the concordance model parameters. This time-compression problem would therefore be inconsistent with the age-redshift relation predicted by ΛCDM. Instead, the sequence of star formation and galaxy assembly would confirm the timeline predicted by the Rh = ct universe, a theoretically advanced version of ΛCDM that incorporates the ‘zero active mass’ condition from general relativity. This model has accounted for many co...
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Cornell University - arXiv, Nov 11, 2022
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Monthly Notices of the Royal Astronomical Society, 2023
The sample of time-delay gravitational lenses appropriate for studying the geometry of the Univer... more The sample of time-delay gravitational lenses appropriate for studying the geometry of the Universe continues to grow as dedicated campaigns, such as the Dark Energy Survey, the (Very Large Telescope) VLT Survey Telescope (VST) ATLAS survey, and the Large Synoptic Survey Telescope, complete their census of high-redshift sources. This catalogue now includes hundreds of strong lensing systems, at least 31 of which have reasonably accurate time-delay measurements. In this paper, we use them to compare the predictions of two competing Friedmann–Lemaître–Robertson–Walker models: flat Lambda cold dark matter (ΛCDM), characterized by two adjustable parameters (H0 and Ωm), and the Rh = ct universe (with H0 as the single free variable). Over the past decade, the latter has accounted for the data better than the standard model, most recently the emergence of well-formed galaxies discovered by JWST at cosmic dawn. Here, we show that the current sample of time-delay lenses favours Rh = ct with ...
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Modern cosmology is broadly based on the Cosmological principle, which assumeshomogeneity and iso... more Modern cosmology is broadly based on the Cosmological principle, which assumeshomogeneity and isotropy as its foundational pillars. Thus, there isn't muchdebate about the metric (i.e., Friedmann-Lemaitre-Robertson-Walker; FLRW)one should use to describe the cosmic spacetime. But Einstein's equations do notunilaterally constrain the constituents in the cosmic fluid, which directly determine the expansion factor appearing in the metric coefficients. As its name suggests, LCDM posits that the energy density is dominated by a blend of dark energy (typically a cosmological constant, Lambda), cold dark matter (and a `contamination' of baryonic matter) and radiation. Many would assert that we have now reached the age of `precision' cosmology, in which measurements are made merely to refine the excessively large number of free parameters characterizing its empirical underpinnings. But this mantra glosses over a growingbody of embarrassingly significant failings, not just `te...
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Physics of the Dark Universe
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Physica Scripta, 2022
The Universe appears to have a ‘preferred’ frame of reference, within which the cosmic microwave ... more The Universe appears to have a ‘preferred’ frame of reference, within which the cosmic microwave background is completely isotropic. Earth’s motion through this relic radiation field is measurable, and some have viewed this type of observation as a possible contradiction of Einstein’s principle of relativity. Several experiments have been proposed (and some have been carried out) to test for violations of Lorentz invariance when transforming out of this background frame, e.g., based on expected velocity differences in a Michelson-Morley type of probe. But what exactly is this cosmic frame? Is it truly an absolute frame attached to the Universe, or is it an observer-dependent construction? Such possibilities represent very different Physics, of course. In this paper, we work through these issues carefully, without the introduction of unsubstantiated assumptions. We show that the preferred frames originate through general (not special) relativity, and are indeed observer-dependent. Th...
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Modern Physics Letters A, 2022
The Friedmann–Lemaître–Robertson–Walker (FLRW) metric used to describe the cosmic spacetime is ba... more The Friedmann–Lemaître–Robertson–Walker (FLRW) metric used to describe the cosmic spacetime is based on the cosmological principle, which assumes homogeneity and isotropy throughout the Universe. It also adopts free-fall conditions via the selection of a constant lapse function, [Formula: see text], regardless of whether or not the chosen energy–momentum tensor [Formula: see text] produces an accelerated expansion. This is sometimes justified by arguing that one may shift the gauge, if necessary, transforming the time [Formula: see text] to a new coordinate [Formula: see text], thereby re-establishing a unitary value for [Formula: see text]. Previously, we have demonstrated that this approach is inconsistent with the Friedmann equations derived using comoving coordinates. In this paper, we advance this discussion significantly by using the Local Flatness Theorem in general relativity to prove that [Formula: see text] in FLRW is inextricably dependent on the expansion dynamics via th...
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The Astrophysical Journal, 2020
With the distance sum rule in the Friedmann–Lemaître–Robertson–Walker metric, model-independent c... more With the distance sum rule in the Friedmann–Lemaître–Robertson–Walker metric, model-independent constraints on both the Hubble constant H 0 and spatial curvature can be obtained using strong lensing time-delay data and Type Ia supernovae (SNe Ia) luminosity distances. This method is limited by the relatively low redshifts of SNe Ia, however. Here, we propose using quasars as distance indicators, extending the coverage to encompass the redshift range of strong lensing systems. We provide a novel and improved method of determining H 0 and simultaneously. By applying this technique to the time-delay measurements of seven strong lensing systems and the known ultraviolet versus X-ray luminosity correlation of quasars, we constrain the possible values of both H 0 and , and find that km and . The measured is consistent with zero spatial curvature, indicating that there is no significant deviation from a flat universe. If we use flatness as a prior, we infer that km , representing a precisi...
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International Journal of Modern Physics D
The baryon acoustic oscillation (BAO) peak, seen in the cosmic matter distribution at redshifts u... more The baryon acoustic oscillation (BAO) peak, seen in the cosmic matter distribution at redshifts up to [Formula: see text]3.5, reflects the continued expansion of the sonic horizon first identified in temperature anisotropies of the cosmic microwave background. The BAO peak position can now be measured to better than [Formula: see text]1% accuracy using galaxies and [Formula: see text]1.4–1.6% precision with Ly-[Formula: see text] forests and the clustering of quasars. In conjunction with the Alcock–Paczyński (AP) effect, which arises from the changing ratio of angular to spatial/redshift size of (presumed) spherically-symmetric source distributions with distance, the BAO measurement is viewed as one of the most powerful tools to use in assessing the geometry of the Universe. In this paper, we employ five BAO peak measurements from the final release of the Sloan Digital Sky Survey IV, at average redshifts [Formula: see text], [Formula: see text], [Formula: see text], [Formula: see te...
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Publications of the Astronomical Society of the Pacific, 2022
Modern cosmology is broadly based on the Cosmological principle, which assumes homogeneity and is... more Modern cosmology is broadly based on the Cosmological principle, which assumes homogeneity and isotropy as its foundational pillars. Thus, there isn't much debate about the metric (i.e., Friedmann-Lemaître-Robertson-Walker; FLRW) one should use to describe the cosmic spacetime. But Einstein's equations do not unilaterally constrain the constituents in the cosmic fluid, which directly determine the expansion factor appearing in the metric coefficients. As its name suggests, ΛCDM posits that the energy density is dominated by a blend of dark energy (typically a cosmological constant, Λ), cold dark matter (and a 'contamination' of baryonic matter) and radiation. Many would assert that we have now reached the age of 'precision' cosmology, in which measurements are made merely to refine the excessively large number of free parameters characterizing its empirical underpinnings. But this mantra glosses over a growing body of embarrassingly significant failings, not just 'tension' as is sometimes described, as if to somehow imply that a resolution will eventually be found. In this paper, we take a candid look at some of the most glaring conflicts between the standard model, the observations, and several foundational principles in quantum mechanics, general relativity and particle physics. One cannot avoid the conclusion that the standard model needs a complete overhaul in order to survive.
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EPJ-C, 2021
Today we have a solid, if incomplete, physical picture of how inertia is created in the standard ... more Today we have a solid, if incomplete, physical picture of how inertia is created in the standard model. We know that most of the visible baryonic 'mass' in the Universe is due to gluonic back-reaction on accelerated quarks, the latter of which attribute their own inertia to a coupling with the Higgs field-a process that elegantly and self-consistently also assigns inertia to several other particles. But we have never had a physically viable explanation for the origin of rest-mass energy, in spite of many attempts at understanding it towards the end of the nineteenth century, culminating with Einstein's own landmark contribution in his Annus Mirabilis. Here, we introduce to this discussion some of the insights we have garnered from the latest cosmological observations and theoretical modeling to calculate our gravitational binding energy with that portion of the Universe to which we are causally connected, and demonstrate that this energy is indeed equal to mc 2 when the inertia m is viewed as a surrogate for gravitational mass.
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MNRAS, 2012
Cosmological redshift zzz grows as the Universe expands and is conventionally viewed as a third f... more Cosmological redshift zzz grows as the Universe expands and is conventionally viewed
as a third form of redshift, beyond the more traditional Doppler and gravitational
effects seen in other applications of general relativity. In this paper, we examine the
origin of redshift in the Friedmann-Robertson-Walker metrics with constant spacetime
curvature, and show that---at least for the static spacetimes---the interpretation of zzz as due to the ``stretching" of space is coordinate dependent. Namely, we prove that
redshift may also be calculated solely from the effects of kinematics and
gravitational acceleration. This suggests that its dependence on the expansion
factor is simply a manifestation of the high degree of symmetry in FRW, and
ought not be viewed as evidence in support of the idea that space itself is
expanding.
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American Journal of Physics, 2018
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The most exciting future observation in cosmology will feature a monitoring of thecosmic expansio... more The most exciting future observation in cosmology will feature a monitoring of thecosmic expansion in real time, unlike anything that has ever been attempted before.This campaign will uncover crucial physical properties of the variousconstituents in the Universe, and perhaps answer a simpler questionconcerning whether or not the cosmic expansion is even accelerating. An unambiguousyes/no response to this query will significantly impact cosmology, of course, butalso the standard model of particle physics. Here, we discuss---in a straightforwardway---how to understand the so-called `redshift drift' sought by this campaign, andwhy its measurement will help us refine the standard-model parametersif the answer is `yes.' A `no' answer, on the other hand, could be more revolutionary,in the sense that it might provide a resolution of several long-standing problems andinconsistencies in our current cosmological models. An outcome of zero redshift drift,for example, would obviate ...
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Modern Physics Letters A, 2022
The Friedmann-Lemaître-Robertson-Walker (FLRW) metric used to describe the cosmic spacetime is ba... more The Friedmann-Lemaître-Robertson-Walker (FLRW) metric used to describe the cosmic spacetime is based on the cosmological principle, which assumes homogeneity and isotropy throughout the Universe. It also adopts free-fall conditions via the selection of a constant lapse function, g tt = 1, regardless of whether or not the chosen energy-momentum tensor T αβ produces an accelerated expansion. This is sometimes justified by arguing that one may shift the gauge, if necessary, transforming the time dt to a new coordinate dt ≡ √ g tt dt, thereby re-establishing a unitary value for g t t. Previously, we have demonstrated that this approach is inconsistent with the Friedmann equations derived using comoving coordinates. In this paper, we advance this discussion significantly by using the Local Flatness Theorem in general relativity to prove that g tt in FLRW is inextricably dependent on the expansion dynamics via the expansion factor a(t), which itself depends on the equation-of-state in T αβ. One is therefore not free to choose g tt arbitrarily without ensuring its consistency with the energy-momentum tensor. We prove that the use of FLRW in cosmology is valid only for zero active mass, i.e., ρ + 3p = 0, where ρ and p are, respectively, the total energy density and pressure in the cosmic fluid.
Bookmarks Related papers MentionsView impact
Bookmarks Related papers MentionsView impact
American Astronomical Society Meeting Abstracts, Dec 1, 1999
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Monthly Notices of the Royal Astronomical Society, Nov 18, 2011
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arXiv (Cornell University), Mar 2, 2009
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Zeitschrift für Naturforschung A
The evidence in favor of a Universe expanding at a constant rate, in contrast to the various epis... more The evidence in favor of a Universe expanding at a constant rate, in contrast to the various episodes of deceleration and acceleration expected in the standard model, has been accumulating for over a decade now. In recent years, this inference has been strengthened by a study of the Friedmann–Lemaître–Robertson–Walker (FLRW) metric in relation to Einstein’s principle of equivalence. This earlier work concluded that the choice of lapse function g tt = 1 characterizing the FLRW solution to Einstein’s equations is inconsistent with any kind of accelerated cosmic expansion. In this paper, we demonstrate and confirm this important result by directly testing the self-consistency of four well-known FLRW cosmologies. These include the Milne universe, de Sitter space, the Lanczos universe, and the R h = ct model. We show that only the constantly expanding models (Milne and R h = ct) are consistent with the principle of equivalence, while de Sitter and Lanczos fail the test. We discuss some o...
Bookmarks Related papers MentionsView impact
Monthly Notices of the Royal Astronomical Society: Letters, 2023
The so-called ‘impossibly early galaxy’ problem, first identified via the Hubble Space Telescope’... more The so-called ‘impossibly early galaxy’ problem, first identified via the Hubble Space Telescope’s observation of galaxies at redshifts z > 10, appears to have been exacerbated by the more recent James Webb Space Telescope (JWST) discovery of galaxy candidates at even higher redshifts (z ∼ 17) which, however, are yet to be confirmed spectroscopically. These candidates would have emerged only ∼230 million years after the big bang in the context of ΛCDM, requiring a more rapid star formation in the earliest galaxies than appears to be permitted by simulations adopting the concordance model parameters. This time-compression problem would therefore be inconsistent with the age-redshift relation predicted by ΛCDM. Instead, the sequence of star formation and galaxy assembly would confirm the timeline predicted by the Rh = ct universe, a theoretically advanced version of ΛCDM that incorporates the ‘zero active mass’ condition from general relativity. This model has accounted for many co...
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Cornell University - arXiv, Nov 11, 2022
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Monthly Notices of the Royal Astronomical Society, 2023
The sample of time-delay gravitational lenses appropriate for studying the geometry of the Univer... more The sample of time-delay gravitational lenses appropriate for studying the geometry of the Universe continues to grow as dedicated campaigns, such as the Dark Energy Survey, the (Very Large Telescope) VLT Survey Telescope (VST) ATLAS survey, and the Large Synoptic Survey Telescope, complete their census of high-redshift sources. This catalogue now includes hundreds of strong lensing systems, at least 31 of which have reasonably accurate time-delay measurements. In this paper, we use them to compare the predictions of two competing Friedmann–Lemaître–Robertson–Walker models: flat Lambda cold dark matter (ΛCDM), characterized by two adjustable parameters (H0 and Ωm), and the Rh = ct universe (with H0 as the single free variable). Over the past decade, the latter has accounted for the data better than the standard model, most recently the emergence of well-formed galaxies discovered by JWST at cosmic dawn. Here, we show that the current sample of time-delay lenses favours Rh = ct with ...
Bookmarks Related papers MentionsView impact
Modern cosmology is broadly based on the Cosmological principle, which assumeshomogeneity and iso... more Modern cosmology is broadly based on the Cosmological principle, which assumeshomogeneity and isotropy as its foundational pillars. Thus, there isn't muchdebate about the metric (i.e., Friedmann-Lemaitre-Robertson-Walker; FLRW)one should use to describe the cosmic spacetime. But Einstein's equations do notunilaterally constrain the constituents in the cosmic fluid, which directly determine the expansion factor appearing in the metric coefficients. As its name suggests, LCDM posits that the energy density is dominated by a blend of dark energy (typically a cosmological constant, Lambda), cold dark matter (and a `contamination' of baryonic matter) and radiation. Many would assert that we have now reached the age of `precision' cosmology, in which measurements are made merely to refine the excessively large number of free parameters characterizing its empirical underpinnings. But this mantra glosses over a growingbody of embarrassingly significant failings, not just `te...
Bookmarks Related papers MentionsView impact
Physics of the Dark Universe
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Physica Scripta, 2022
The Universe appears to have a ‘preferred’ frame of reference, within which the cosmic microwave ... more The Universe appears to have a ‘preferred’ frame of reference, within which the cosmic microwave background is completely isotropic. Earth’s motion through this relic radiation field is measurable, and some have viewed this type of observation as a possible contradiction of Einstein’s principle of relativity. Several experiments have been proposed (and some have been carried out) to test for violations of Lorentz invariance when transforming out of this background frame, e.g., based on expected velocity differences in a Michelson-Morley type of probe. But what exactly is this cosmic frame? Is it truly an absolute frame attached to the Universe, or is it an observer-dependent construction? Such possibilities represent very different Physics, of course. In this paper, we work through these issues carefully, without the introduction of unsubstantiated assumptions. We show that the preferred frames originate through general (not special) relativity, and are indeed observer-dependent. Th...
Bookmarks Related papers MentionsView impact
Modern Physics Letters A, 2022
The Friedmann–Lemaître–Robertson–Walker (FLRW) metric used to describe the cosmic spacetime is ba... more The Friedmann–Lemaître–Robertson–Walker (FLRW) metric used to describe the cosmic spacetime is based on the cosmological principle, which assumes homogeneity and isotropy throughout the Universe. It also adopts free-fall conditions via the selection of a constant lapse function, [Formula: see text], regardless of whether or not the chosen energy–momentum tensor [Formula: see text] produces an accelerated expansion. This is sometimes justified by arguing that one may shift the gauge, if necessary, transforming the time [Formula: see text] to a new coordinate [Formula: see text], thereby re-establishing a unitary value for [Formula: see text]. Previously, we have demonstrated that this approach is inconsistent with the Friedmann equations derived using comoving coordinates. In this paper, we advance this discussion significantly by using the Local Flatness Theorem in general relativity to prove that [Formula: see text] in FLRW is inextricably dependent on the expansion dynamics via th...
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The Astrophysical Journal, 2020
With the distance sum rule in the Friedmann–Lemaître–Robertson–Walker metric, model-independent c... more With the distance sum rule in the Friedmann–Lemaître–Robertson–Walker metric, model-independent constraints on both the Hubble constant H 0 and spatial curvature can be obtained using strong lensing time-delay data and Type Ia supernovae (SNe Ia) luminosity distances. This method is limited by the relatively low redshifts of SNe Ia, however. Here, we propose using quasars as distance indicators, extending the coverage to encompass the redshift range of strong lensing systems. We provide a novel and improved method of determining H 0 and simultaneously. By applying this technique to the time-delay measurements of seven strong lensing systems and the known ultraviolet versus X-ray luminosity correlation of quasars, we constrain the possible values of both H 0 and , and find that km and . The measured is consistent with zero spatial curvature, indicating that there is no significant deviation from a flat universe. If we use flatness as a prior, we infer that km , representing a precisi...
Bookmarks Related papers MentionsView impact
International Journal of Modern Physics D
The baryon acoustic oscillation (BAO) peak, seen in the cosmic matter distribution at redshifts u... more The baryon acoustic oscillation (BAO) peak, seen in the cosmic matter distribution at redshifts up to [Formula: see text]3.5, reflects the continued expansion of the sonic horizon first identified in temperature anisotropies of the cosmic microwave background. The BAO peak position can now be measured to better than [Formula: see text]1% accuracy using galaxies and [Formula: see text]1.4–1.6% precision with Ly-[Formula: see text] forests and the clustering of quasars. In conjunction with the Alcock–Paczyński (AP) effect, which arises from the changing ratio of angular to spatial/redshift size of (presumed) spherically-symmetric source distributions with distance, the BAO measurement is viewed as one of the most powerful tools to use in assessing the geometry of the Universe. In this paper, we employ five BAO peak measurements from the final release of the Sloan Digital Sky Survey IV, at average redshifts [Formula: see text], [Formula: see text], [Formula: see text], [Formula: see te...
Bookmarks Related papers MentionsView impact
Publications of the Astronomical Society of the Pacific, 2022
Modern cosmology is broadly based on the Cosmological principle, which assumes homogeneity and is... more Modern cosmology is broadly based on the Cosmological principle, which assumes homogeneity and isotropy as its foundational pillars. Thus, there isn't much debate about the metric (i.e., Friedmann-Lemaître-Robertson-Walker; FLRW) one should use to describe the cosmic spacetime. But Einstein's equations do not unilaterally constrain the constituents in the cosmic fluid, which directly determine the expansion factor appearing in the metric coefficients. As its name suggests, ΛCDM posits that the energy density is dominated by a blend of dark energy (typically a cosmological constant, Λ), cold dark matter (and a 'contamination' of baryonic matter) and radiation. Many would assert that we have now reached the age of 'precision' cosmology, in which measurements are made merely to refine the excessively large number of free parameters characterizing its empirical underpinnings. But this mantra glosses over a growing body of embarrassingly significant failings, not just 'tension' as is sometimes described, as if to somehow imply that a resolution will eventually be found. In this paper, we take a candid look at some of the most glaring conflicts between the standard model, the observations, and several foundational principles in quantum mechanics, general relativity and particle physics. One cannot avoid the conclusion that the standard model needs a complete overhaul in order to survive.
Bookmarks Related papers MentionsView impact
EPJ-C, 2021
Today we have a solid, if incomplete, physical picture of how inertia is created in the standard ... more Today we have a solid, if incomplete, physical picture of how inertia is created in the standard model. We know that most of the visible baryonic 'mass' in the Universe is due to gluonic back-reaction on accelerated quarks, the latter of which attribute their own inertia to a coupling with the Higgs field-a process that elegantly and self-consistently also assigns inertia to several other particles. But we have never had a physically viable explanation for the origin of rest-mass energy, in spite of many attempts at understanding it towards the end of the nineteenth century, culminating with Einstein's own landmark contribution in his Annus Mirabilis. Here, we introduce to this discussion some of the insights we have garnered from the latest cosmological observations and theoretical modeling to calculate our gravitational binding energy with that portion of the Universe to which we are causally connected, and demonstrate that this energy is indeed equal to mc 2 when the inertia m is viewed as a surrogate for gravitational mass.
Bookmarks Related papers MentionsView impact
MNRAS, 2012
Cosmological redshift zzz grows as the Universe expands and is conventionally viewed as a third f... more Cosmological redshift zzz grows as the Universe expands and is conventionally viewed
as a third form of redshift, beyond the more traditional Doppler and gravitational
effects seen in other applications of general relativity. In this paper, we examine the
origin of redshift in the Friedmann-Robertson-Walker metrics with constant spacetime
curvature, and show that---at least for the static spacetimes---the interpretation of zzz as due to the ``stretching" of space is coordinate dependent. Namely, we prove that
redshift may also be calculated solely from the effects of kinematics and
gravitational acceleration. This suggests that its dependence on the expansion
factor is simply a manifestation of the high degree of symmetry in FRW, and
ought not be viewed as evidence in support of the idea that space itself is
expanding.
Bookmarks Related papers MentionsView impact
American Journal of Physics, 2018
Bookmarks Related papers MentionsView impact
The most exciting future observation in cosmology will feature a monitoring of thecosmic expansio... more The most exciting future observation in cosmology will feature a monitoring of thecosmic expansion in real time, unlike anything that has ever been attempted before.This campaign will uncover crucial physical properties of the variousconstituents in the Universe, and perhaps answer a simpler questionconcerning whether or not the cosmic expansion is even accelerating. An unambiguousyes/no response to this query will significantly impact cosmology, of course, butalso the standard model of particle physics. Here, we discuss---in a straightforwardway---how to understand the so-called `redshift drift' sought by this campaign, andwhy its measurement will help us refine the standard-model parametersif the answer is `yes.' A `no' answer, on the other hand, could be more revolutionary,in the sense that it might provide a resolution of several long-standing problems andinconsistencies in our current cosmological models. An outcome of zero redshift drift,for example, would obviate ...
Bookmarks Related papers MentionsView impact
Modern Physics Letters A, 2022
The Friedmann-Lemaître-Robertson-Walker (FLRW) metric used to describe the cosmic spacetime is ba... more The Friedmann-Lemaître-Robertson-Walker (FLRW) metric used to describe the cosmic spacetime is based on the cosmological principle, which assumes homogeneity and isotropy throughout the Universe. It also adopts free-fall conditions via the selection of a constant lapse function, g tt = 1, regardless of whether or not the chosen energy-momentum tensor T αβ produces an accelerated expansion. This is sometimes justified by arguing that one may shift the gauge, if necessary, transforming the time dt to a new coordinate dt ≡ √ g tt dt, thereby re-establishing a unitary value for g t t. Previously, we have demonstrated that this approach is inconsistent with the Friedmann equations derived using comoving coordinates. In this paper, we advance this discussion significantly by using the Local Flatness Theorem in general relativity to prove that g tt in FLRW is inextricably dependent on the expansion dynamics via the expansion factor a(t), which itself depends on the equation-of-state in T αβ. One is therefore not free to choose g tt arbitrarily without ensuring its consistency with the energy-momentum tensor. We prove that the use of FLRW in cosmology is valid only for zero active mass, i.e., ρ + 3p = 0, where ρ and p are, respectively, the total energy density and pressure in the cosmic fluid.
Bookmarks Related papers MentionsView impact