Space

NASA Scientists Probe Dark Energy – Time To Rework Albert Einstein’s Theory of Gravity?

Dark Energy Illustration

Dark energy illustration. Credit: Visualization by Frank Summers, Space Telescope Science Institute. Simulation by Martin White, UC Berkeley and Lars Hernquist, Harvard University

Could one of the biggest puzzles in astrophysics be solved by reworking Albert Einstein’s theory of gravity? Not yet, according to a new study co-authored by NASA scientists.

The universe is expanding at an accelerating rate, and physicists don’t know why. This phenomenon seems to contradict everything scientists understand about gravity’s effect on the cosmos: It’s as if you threw an apple in the air and instead of coming back down, it continued upward, faster and faster. The cause of the cosmic acceleration, dubbed dark energy, remains a mystery.

A new study marks the latest effort to determine whether this is all simply a misunderstanding: that expectations for how gravity works at the scale of the entire universe are flawed or incomplete. This potential misunderstanding might help researchers explain dark energy. However, the study – one of the most precise tests yet of Albert Einstein’s theory of gravity at cosmic scales – finds that the current understanding still appears to be correct. The study was from the international Dark Energy Survey, using the Victor M. Blanco 4-meter Telescope in Chile.

The results, authored by a group of scientists that includes some from NASA’s Jet Propulsion Laboratory (JPL), were presented Wednesday, August 24, at the International Conference on Particle Physics and Cosmology (COSMO’22) in Rio de Janeiro. The work helps set the stage for two upcoming space telescopes that will probe our understanding of gravity with even higher precision than the new study and perhaps finally solve the mystery.

This image – the first released from NASA’s James Webb Space Telescope – shows the galaxy cluster SMACS 0723. Some of the galaxies appear smeared or stretched due to a phenomenon called gravitational lensing. This effect can help scientists map the presence of dark matter in the universe. Credit: NASA, ESA, CSA, and STScI

More than a century ago, Albert Einstein developed his Theory of General Relativity to describe gravity. Thus far it has accurately predicted everything from the orbit of Mercury to the existence of black holes. But some scientists have argued that if this theory can’t explain dark energy, then maybe they need to modify some of its equations or add new components.

To find out if that’s the case, members of the Dark Energy Survey looked for evidence that gravity’s strength has varied throughout the universe’s history or over cosmic distances. A positive finding would indicate that Einstein’s theory is incomplete, which might help explain the universe’s accelerating expansion. They also examined data from other telescopes in addition to Blanco, including the ESA (European Space Agency) Planck satellite, and reached the same conclusion.

Einstein’s theory still works, according to the study. So no there’s no explanation for dark energy yet. However, this research will feed into two upcoming missions: ESA’s Euclid mission, slated for launch no earlier than 2023, which has contributions from NASA; and NASA’s Nancy Grace Roman Space Telescope, targeted for launch no later than May 2027. Both telescopes will search for changes in the strength of gravity over time or distance.

Blurred Vision

How do scientists know what happened in the universe’s past? By looking at distant objects. A light-year is a measure of the distance light can travel in a year (about 6 trillion miles, or about 9.5 trillion kilometers). That means an object one light-year away appears to us as it was one year ago, when the light first left the object. And galaxies billions of light-years away appear to us as they did billions of years ago. The new study looked at galaxies stretching back about 5 billion years in the past. Euclid will peer 8 billion years into the past, and Roman will look back 11 billion years.

The galaxies themselves don’t reveal the strength of gravity, but how they look when viewed from Earth does. Most matter in our universe is dark matter, which does not emit, reflect, or otherwise interact with light. While physicists don’t know what it’s made of, they know it’s there, because its gravity gives it away: Large reservoirs of dark matter in our universe warp space itself. As light travels through space, it encounters these portions of warped space, causing images of distant galaxies to appear curved or smeared. This was on display in one of first images released from NASA’s James Webb Space Telescope.


This video explains the phenomenon called gravitational lensing, which can cause images of galaxies to appear warped or smeared. This distortion is caused by gravity, and scientists can use the effect to detect dark matter, which does not emit or reflect light. Credit: NASA’s Goddard Space Flight Center

Dark Energy Survey scientists search galaxy images for more subtle distortions due to dark matter bending space, an effect called weak gravitational lensing. The strength of gravity determines the size and distribution of dark matter structures, and the size and distribution, in turn, determine how warped those galaxies appear to us. That’s how images can reveal the strength of gravity at different distances from Earth and distant times throughout the universe’s history. The group has now measured the shapes of over 100 million galaxies, and so far, the observations match what’s predicted by Einstein’s theory.

“There is still room to challenge Einstein’s theory of gravity, as measurements get more and more precise,” said study co-author Agnès Ferté, who conducted the research as a postdoctoral researcher at JPL. “But we still have so much to do before we’re ready for Euclid and Roman. So it’s essential we continue to collaborate with scientists around the world on this problem as we’ve done with the Dark Energy Survey.”

Reference: “Dark Energy Survey Year 3 Results: Constraints on extensions to ΛCDM with weak lensing and galaxy clustering” by DES Collaboration: T. M. C. Abbott, M. Aguena, A. Alarcon, O. Alves, A. Amon, J. Annis, S. Avila, D. Bacon, E. Baxter, K. Bechtol, M. R. Becker, G. M. Bernstein, S. Birrer, J. Blazek, S. Bocquet, A. Brandao-Souza, S. L. Bridle, D. Brooks, D. L. Burke, H. Camacho, A. Campos, A. Carnero Rosell, M. Carrasco Kind, J. Carretero, F. J. Castander, R. Cawthon, C. Chang, A. Chen, R. Chen, A. Choi, C. Conselice, J. Cordero, M. Costanzi, M. Crocce, L. N. da Costa, M. E. S. Pereira, C. Davis, T. M. Davis, J. DeRose, S. Desai, E. Di Valentino, H. T. Diehl, S. Dodelson, P. Doel, C. Doux, A. Drlica-Wagner, K. Eckert, T. F. Eifler, F. Elsner, J. Elvin-Poole, S. Everett, X. Fang, A. Farahi, I. Ferrero, A. Ferté, B. Flaugher, P. Fosalba, D. Friedel, O. Friedrich, J. Frieman, J. García-Bellido, M. Gatti, L. Giani, T. Giannantonio, G. Giannini, D. Gruen, R. A. Gruendl, J. Gschwend, G. Gutierrez, N. Hamaus, I. Harrison, W. G. Hartley, K. Herner, S. R. Hinton, D. L. Hollowood, K. Honscheid, H. Huang, E. M. Huff, D. Huterer, B. Jain, D. J. James, M. Jarvis, N. Jeffrey, T. Jeltema, A. Kovacs, E. Krause, K. Kuehn, N. Kuropatkin, O. Lahav, S. Lee, P.-F. Leget, P. Lemos, C. D. Leonard, A. R. Liddle, M. Lima, H. Lin, N. MacCrann, J. L. Marshall, J. McCullough , J. Mena-Fernández, F. Menanteau, R. Miquel, V. Miranda, J. J. Mohr, J. Muir, J. Myles, S. Nadathur, A. Navarro-Alsina, R. C. Nichol, R. L. C. Ogando, Y. Omori, A. Palmese, S. Pandey, Y. Park, M. Paterno, F. Paz-Chinchón, W. J. Percival, A. Pieres, A. A. Plazas Malagón, A. Porredon, J. Prat, M. Raveri, M. Rodriguez-Monroy, P. Rogozenski, R. P. Rollins, A. K. Romer, A. Roodman, R. Rosenfeld, A. J. Ross, E. S. Rykoff, S. Samuroff, C. Sánchez, E. Sanchez, J. Sanchez, D. Sanchez Cid, V. Scarpine, D. Scolnic, L. F. Secco, I. Sevilla-Noarbe, E. Sheldon, T. Shin, M. Smith, M. Soares-Santos, E. Suchyta, M. Tabbutt, G. Tarle, D. Thomas, C. To, A. Troja, M. A. Troxel, I. Tutusaus, T. N. Varga, M. Vincenzi, A. R. Walker, N. Weaverdyck, R. H. Wechsler, J. Weller, B. Yanny, B. Yin, Y. Zhang and J. Zuntz, 12 July 2022, Astrophysics > Cosmology and Nongalactic Astrophysics.
arXiv:2207.05766

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  • Yes, I agree that there's a misunderstanding, but not that gravity works differently depending on where you are.

    Another way to explain Dark Energy is suggested by String Theory. All matter and energy, including photons (light), have vibrating strings as their basis.

    String and anti-string pairs are speculated to be created in the quantum foam, a roiling energy field suggested by quantum mechanics, and they immediately annihilate each other. If light passes near these string/anti-string annihilations, perhaps some of that annihilation energy is absorbed by the string in the light. Then the Fraunhofer lines in that light will move a bit towards the blue and away from the red shift. As this continues in an expanding universe we get the same curve displayed by Perlmutter and colleagues at their Nobel Prize lecture, without the need for Dark Energy.

    This speculation has the universe behaving in a much more direct way. Specifics on this can be found by searching YouTube for “Dark Energy – a String Theory Way”

    • No such thing as 'dark energy' or 'dark matter.' Because we all exist in a rather dense 'well' of solar system gravity, it really strains the brain to imagine what it's like in deep space. However, my personal 2009 'insight' into gravity not only informs me that there is little gravity in deep space, but has now suggested a second and third proof of my model of gravity down here on earth. Not only is it pulsing directional locally induced lines of gravity force which make photons appear as both particles and waves in double-slit experiments but that also causes a blurring effect in photos taken with pinhole cameras. With photons traveling in relatively straight lines while in deep space, gravitational lensing still occurs as they travel in the vicinity of large cosmic objects. Less obvious, as the arc of the gravity lines of force of a star become greater farther from the star, their attraction causes less 'jiggling' photons to increase in velocity, with the opposite occurring when they arrive in our solar system's increasingly dense field. The speed of light is not a constant and the age and size of the universe need to be recalculated, if someone more mathematical than I can determine exactly how to factor-in the variable 'jiggle' of interstellar/intergalactic photons.

  • Dark matter has aura-like nonlocal wave inflections revealed best in gravity from sufficiently strong compact sources in low energy surroundings, and gravity is, of course, negative energy.

    The dark matter notion there simply falls out of source-synchronized quantized gravity field carrier rotation at galactic scale as it shows how the so-called "placeholder concept" shows rigging and bias in the words of dark matter advocates displacing true sources from the start.

    Another intriguing correction for gravity that the media prestige game is rigged against revealing is any notion of natural focusing of gravitational information flow by cooling matter.

    The standard punishment for revealing such simple concepts is merely more incoming biased media reinforcement aimed at the comment and/or messenger.

  • Another simple notion worth mentioning here is that "dark energy" as largely the relatively positive energy effect of the source-relative flip side of galactic-rate rotating gravity field carriers. A cooling-matter focus effect should dominate the cold extremum of a hot-matter/unfocused-gravity and cold-matter/focused-gravity universe.

  • For a very nice fit to galactic-rate rotating vector field gravity, check out the latest redshift-blueshift color map of Milky way Rotation rate, which shows an inner ring turning one way, and an outer ring rotating in the opposite direction.

    For a very nice fit to focused cold Milky Way central black hole gravity forming a diamond-like lattice, see the latest XYZ 3-plane-highlight BH VLBA radio image.

    The idea of cold gravity focus is a natural fit to simple nucleonic scale dynamics where each momentum system in a tri-quark condenses into one of three orthogonal disk-like gravity carrier semi-reflective objects. Gravity is quantized as a self-compressed mixture of true and false vacuum energy to easily fit within nucleonic-scale interactions with zero net mass and energy capable of carrying rotational momentum; carrier collapse is a directed micro-tensor. A rotating vector field model fits a true-false vacuum dipole initialized with a leading false vacuum edge. It's fundamentally spin-1 and twinnable back-to-back for spin-2.

  • Gravity focus may explain entanglement. Entanglement apparatus is typically of low enough temperature to carry retro-reflected nucleonic lateral spin couplings, wherever there is a stabilized one-way path for light including splitters there exists a 2-way path for enhanced spin-coupling gravity between splitters. It helps to suppose gravity conducts spin information faster when more focused, up to a natural saturation limit, capable of critically guiding both photon emission and collapse. Omnidirectional retro-reflection in ultimate Cold focus may be analogized to Hebbian flows, for whatever that is worth considering all apparatuses are extensions of decision processes.

  • Astrophysicts may come to appreciate that dark matter may be made up of a soup of assorted energised inert nano-particles, which cause gravity as they interact amongst themselves and with solid or tangible matter. The most credible theory to-date holds that gravity manifestation is a net effect of energised particles cancelling out their all-sided pressure on tangible natter. This act of gravity tends to suggest either that the dark matter space is infinity if the universe is not expanding, or that the dark matter space is finite and expanding our into unoccupied voids hence causing the universe embedded in it to expand out with it

  • It occurred to me that gravity is also a property of time as well as space because without the relationship of dynamic time with static space or space-time, space wouldn’t move us forward into the future. Also time doesn’t react with anything as does dark matter or dark energy.

  • It occurred to me that gravity is also a property of time as well as space because without the relationship of dynamic time with static space or space-time, space wouldn’t move us forward into the future. Also time doesn’t react with anything as does dark matter or dark energy.

By
Calla Cofield, Jet Propulsion Laboratory

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