Beyond Einstein: Gravitational Rainbows

Whenever I become frustrated with our politics, politicians & some of the societal filth and imperfections, I listen to these podcasts to ground myself back to the beauty of nature & life.

As most of you, I've seen hours of conversations in this channel. All of them are so interesting. I know basic mathematics... I barely remember how to do equations, some trigonometry...the way the topics are explained, help us visualize some "forces" and "fields" without knowing the mathematics of it. This channel is a gold mine. Love it. Brian Greene 👏🏼

Best feeling in the world of science right here: a huge problem (dark energy) leads to an hypothesis (gravitational rainbows) and our technology just happens to be ripe enough to develop experiments to test it (Ligo, et al.). And the cherry on top is we have this amazing platform (Youtube) to hear of these unfolding wonders from the mouths of the utmost experts in the field. WSF is a gift to Humanity. Thank you Brian Greene.

Great title, great subject, great people, great talk. This channel almost never disappoints.

The video is from the World Science Festival and features a discussion between theoretical physicist Claudia de Rham and host Brian Greene about gravity, dark energy, and the potential for new insights from studying "gravitational rainbows." Key points: 1. Newton's theory of gravity stood unchallenged for centuries and worked very well to explain the motions of planets in the solar system. However, Newton himself realized his theory had a flaw in that it allowed gravity to act instantaneously across any distance, which didn't seem sensible. 2. In the early 20th century, Einstein radically overhauled Newton's theory of gravity with his general theory of relativity. Einstein showed that gravity is not a force as Newton described, but is instead the curvature of spacetime itself caused by the presence of mass and energy. 3. Einstein struggled to accept some of the implications of his own theory, including an expanding universe, black holes, and gravitational waves. He also introduced but later abandoned the idea of a "cosmological constant" - an invisible energy permeating space. 4. In recent decades, the idea of a cosmological constant has roared back in the form of dark energy. Observations in the late 1990s showed that the expansion of the universe is accelerating, driven by some unknown energy. This energy acts like Einstein's cosmological constant. 5. The true nature of dark energy remains one of the biggest mysteries in physics. Calculations based on quantum theory predict a vacuum energy that should act like dark energy, but the predicted amount is vastly larger than observations allow - a discrepancy of up to 120 orders of magnitude. This is perhaps the biggest gap between theory and observation in the history of science. 6. Claudia de Rham and others are investigating ways we might be able to probe the properties of dark energy more directly. One intriguing idea is studying "gravitational rainbows." 7. Just as light waves can split into a rainbow spectrum when passing through water droplets, gravitational waves might split into a spectrum of frequencies as they pass through the "medium" of dark energy permeating space. Studying this gravitational rainbow effect could provide new insights into dark energy. 8. Gravitational waves themselves were predicted by Einstein's theory but he doubted they would ever be detected. In 2015, a century after Einstein's theory, gravitational waves were finally directly observed for the first time by the LIGO detectors. 9. Detecting gravitational waves has opened up a whole new way to study the universe. Upcoming space-based detectors and other approaches may allow detection of very low frequency gravitational waves with wavelengths nearly as large as the observable universe. Studying how these waves propagate through space could reveal subtle effects of dark energy. 10. In addition to probing dark energy, studying gravitational waves in more detail could potentially reveal that gravity has additional polarization states beyond the two that are predicted by Einstein's theory and have been observed so far. Finding additional polarizations would be a major discovery showing that Einstein's theory needs to be extended or modified. In summary, while Einstein's general theory of relativity radically reshaped our understanding of gravity and spacetime over a century ago, observations in recent decades have shown there is still much we don't understand about gravity and the universe at the largest scales. The discovery that the expansion of the universe is accelerating, driven by an unknown dark energy, is one of the biggest challenges for fundamental physics. At the same time, the detection of gravitational waves has given scientists a powerful new tool to study gravity and probe some of these deep mysteries.

I'm addict to this youtube channel and to Sean Caroll one too. It has been so long before this serie of 3 episodes. ❤much love for you all working behind the scene of this show and to Brian too of course.

I wish this was longer. She was an excellent speaker and I think would have shared even more great theories/research if given more time. Please have her back 😊

Rewatched this like 5 times already. Started following WSF channel close to their launch many years ago. So underrated. People dont even know what they dont know. Life is so much better thanks to Brian Greene.

Brian is a great educational facilitator.

Dr De Rham is brilliant, she and her colleagues are on the right track,finally...

Very informative and enlightening discussion on a topic close to my heart. Love the series by Prof. Green on a diverse set of topics that are contemporary and significant for any STEM followers like me

General Relativity predicts dilation, not singularities. In the 1939 journal "Annals of Mathematics" Einstein wrote - "The essential result of this investigation is a clear understanding as to why the Schwarzchild singularities (Schwarzchild was the first to raise the issue of General Relativity predicting singularities) do not exist in physical reality. Although the theory given here treats only clusters (star clusters) whose particles move along circular paths it does seem to be subject to reasonable doubt that more general cases will have analogous results. The Schwarzchild singularities do not appear for the reason that matter cannot be concentrated arbitrarily. And this is due to the fact that otherwise the constituting particles would reach the velocity of light." He was referring to the phenomenon of dilation (sometimes called gamma or y) mass that is dilated is smeared through spacetime relative to an outside observer. It's the phenomenon behind the phrase "mass becomes infinite at the speed of light". Time dilation is just one aspect of dilation. Dilation will occur wherever there is an astronomical quantity of mass because high mass means high momentum. It's the original and correct explanation for why we cannot see light from the galactic center. It can be inferred mathematically that dilation is occurring in our own galactic center. In other words that mass is all around us. Sound familiar? This is the explanation for the abnormally high rotation rates of stars in spiral galaxies. The "missing mass" is dilated mass. It also explains why all planets and all binary stars have normal rotation rates, not 3 times normal. Dilation does not occur in galaxies with low mass centers because they do not have enough mass to achieve relativistic velocities. To date, 6 very low mass galaxies including NGC 1052-DF2 and DF4 have been confirmed to show no signs of dark matter. There was clarity in astronomy before television and movies popularized singularities starting in the 1960's. Einstein is known to have repeatedly said that they cannot exist. Nobody believed in them when he was alive including Plank, Bohr, Schrodinger, Dirac, Heisenberg, Feynman etc.

its 3.04 AM and this is very fascinating. I am going to sleep now

estoy conmovida! qué maravilloso momento en la historia para presenciarlo

Dr. Greene the formats of the three videos released on or about 3/9/24 were over far too soon. Hope WSF returns to its longer format and discussions. Thank you for the exceptionally expert guests you invite and the brilliant discussions. What a generous, priceless gift! Look forward to future (hopefully longer, please) episodes and to see the WSF live. May you “…live long and prosper…” Prof Greene. ✨

Excited

Such great series... Thank you..👏👏👏💯💯💯

THANK YOU...!!!

Incredible

Such a profound and deep❤