Renowned cosmologist David Spergel joins Brian Greene to discuss the triumphs and tensions of precision cosmology, exploring remarkable successes as well as persistent discrepancies bedeviling current understanding.
This program is part of the Big Ideas series, supported by the John Templeton Foundation.
Participant: David Spergel
Moderator: Brian Greene
0:00:00 – Introduction
0:00:35 – Welcome to David Spergel
0:07:20 – Spergel’s involvement on WMAP project
0:14:53 – Measuring temperature and polarization of the microwave background
0:21:35 – How Planck satellite refined WMAP measurements
0:23:38 – Tension with the measurement of the Hubble Constant
0:28:20 – Potential further refinement from data from James Webb Space Telescope
0:29:34 – Strengths and weaknesses of framework of Inflationary Cosmology
0:38:03 – Cosmological gravitational waves’ impact on the microwave background
0:47:53 – Paul Steinhardt’s Cyclic Cosmology
0:50:15 – Spergel’s thoughts on the multiverse
0:52:54 – Dark matter and dark energy
1:02:10 – The language of mathematics
1:04:15 – Conclusion
1:04:50 – Credits
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It always puzzles me why people don't like the idea of the multiverse. We know that our universe exists, although we have no idea why. However, knowing that our universe came into existence at some point, why would you assume that no other universe could come into existence through the same mechanism, whatever it might be? The natural assumption should be that other universes probably do exist, unless you can come up with a good reason why our universe is unique.
It's interesting to look at the history of human understanding of cosmology. At first we thought that the earth was unique. Then we discovered that earth was just one of several planets, but thought that the solar system was unique. When we discovered that the sun was just one of many stars in our galaxy, we assumed that our galaxy was unique. Then we realised that our galaxy was just one of countless others. Currently, many people now seem to assume that our universe is unique. Just another assumption in a line of conceits about how special we are.
What a great conversation! I agree with Brian, Maths is invented.
Great guest! David Spergel was also recently on Startalk to talk about aliens 👽
dye dee dOh
💧💧🐳💧🐋🐳🐙🐙🐳🐋💧🐳💧💧
Brian Greene will always be my Goat
Math is incredibly good at describing nature because it doesn't discriminate (especially in the users heads): whatever you want math to describe, it would do it for you…. as Freeman Dyson's boss, Fermi, reminded him … of what Fermi's own boss reminded him, years before…
What mathematicians don't want to admit is that for every Neptune found, using mathematical calculations alone, there are many more planet Vulcan's not found, using mathematics .
Good ole' Fritz Zwicky's 1920 – 30's postulated "Dark Matter" is LIKELY one of those Planet Vulcan things…
Close to 100% of "working cosmologists and astronomers" are now, or have been since Zwicky's days, into this highly attractive "Dark Matter" thing.
Many go so far as to say they've FOUND IT.
They just don't know what it is! They say they KNOW HOW IT WORKS; they just don't know what it is made of.
It's existence is everywhere, Dark Matter's proponents say…. except some regions in space where it is not found…
They say it's found in all faster-than-normal galactic rotations, except in some galaxies or in PARTS of galactic structures, like in dense cores where there are enough ordinary matter, with no need for "dark matter."
They say, Dark Matter is responsible for the deflection of light around massive galactic structures.
But that phenomenon is explained away by a Freshman introductory course in General Reality, with the extreme curvature of space-time, in massive structures, acting as "mirrors" (that "deflects" light) for photons falling JUST outside of the Schwarzschild radius, etc.
Anyway, it behooves people to remember that close 100% of these same cosmologists & astronomers also believed, until as late as ~1997…. that the Universe expansion rate was SLOWING DOWN…. and they merely needed lowly paid post doc's to work out the details on the rate of that slowing down.
The point here is not so much about the best & brightest being wrong about Planet Vulcan.
It also is NOT that there are events, processes, and/or terrains — on both the Planck scale and the larger structures of the Universe —- that even the best and brightest among humanity WILL CONSISTENTLY FAIL TO UNDERSTAND…
Those are given.
The point, rather, is that due to a combination of natural ignorance & arrogance, humanity's "best and brightest" CONSISTENTLY make persistent & glaring mistakes that they shouldn't be making…
The "best and brightest" in Classical Greece only had free straws and cooking utensils to test the existence of air molecules.
Today, we have MULTI-BILLION DOLLAR tax funded instruments that take decades to envision and to build…
Mathematicians have a refined perspective on the question of whether mathematics is invented or discovered, and it is beautifully encapsulated in category theory. Category theory reveals the deep structures that underlie mathematics and points to what is truly universal and natural. For this reason, many mathematicians familiar with it would agree that string theory feels more like a human invention than a discovery of nature’s inherent truths.
Moreover, most would concur that intelligent beings elsewhere in the universe, regardless of their biology or technology, would likely have discovered much of what category theory identifies as fundamental and universal. Speaking as a mathematician myself, my own choices about what to explore are often guided by the elegant principles revealed through category theory.
Have you noticed no one is listening to you and your ilk anymore.
Thank you so much for brightening our knowledge. I love your technique. You doesn't deluge your guest a continued barrage of questions, but rathe ask poignant questions that allow the guest to unfurl the gems of their knowledge. Thank you and please keep going. Love it.
Please! Disable the voice translation! It makes it horrible to listen to anyway and it can't be disabled on the user side! (This is a bug I guess)
Thanks.
Would absolutely LOVE to hear you two debate more about the nature of mathematics
Great video. Someone once said "All Biology can be described with Chemistry , all Chemistry can be described with Physics, and all Physics can be described by Mathematics.
a bunch of hogwaller! It will change in a few years…… I still kinda liked it?
Excellent discussion. Thanks Brian and David. Cheers from Canada.
Funny how you can be so smart and yet so stupid.(Spergel while condeming protests at Princeton. He's a pathetic supremacist).
"Grammatical Man" 1982, drove my interest to be enlightened!
This is one of your best interviews yet… solid, down-to-earth, no-nonsense content. The only place where your guest drifted from this for me was toward the end when he expressed skepticism for the (unfortunately-named) anthropic principle on the basis that there could be many values for lambda (and other fine-tuned constants) that could give rise to a 'universe' compatible for life. SO WHAT? In a ‘landscape’ as suggested by Susskind there would be many possible sets of constants that might give rise to ‘universes’ with the necessary complexity for life, with many of them being unimaginably exotic vis-à-vis our ‘universe;’ just as there would be vastly more sterile and likely short-lived ‘universes.’ As your guest did acknowledge, just because there is yet, and may never be any proof for multiple ‘universes,’ doesn’t mean that it isn’t correct. The bottom line is the Copernican principle; it is human hubris to think that all we can observe is all there is. Surely Occam’s Razor would suggest that a single ‘universe’ with its arbitrary fine tunings is the one that requires explanation; and that a many-universe theme is a natural extension of what we know. Part of the problem is that like the ‘anthropic principle,’ the ‘multiverse’ is similarly unfortunately named. Better that we redefine all that we can observe as a small part of the ‘universe’ and come up with a new name for what we hitherto called the 'universe'. How about ‘local universe?’ Whether string theory or something like it is ever substantiated, something like the ‘landscape’ is likely to represent reality. It’s like the question “why is there something rather than nothing?” The answer to that, surely, is that ‘nothing’ would be a special case requiring explanation. On your closing question about mathematics, I think you’re both right: fundamentals are ‘discovered’ and much of the exotic stuff is invented.
so awesome!! ended fantastic!! thank you all!!
Incredible talk, really appreciate.
Top interview – this guy is super knowledgeable.
The universe cannot be mathematical because of the infinity and zero problem imo its informational – 0s and 1s are pretty mathematical from the get go.
"How Science Revealed a Simple Universe: The Winding Road to Cosmic Breakthroughs"
Now… I KNOW Brian Greene has a good understanding of quantum mechanics and relativity, and all the complexities and weirdnesses those have especially when you try to bring them together… so I'm really having an issue with title of this video.
Newtonian physics described a simple universe.
It's gotten progressively weirder and more complex since. I mean, the standard equation has over 200 terms in it and most of those terms are "contractions" of more complex equations.
Even with cosmology we went from "a dome in the sky with holes to let light in" to a complex spacetime with dark energy that no one can prove exists (for sure) and dark matter that no one can detect (for sure) and a universe that's expanding ever faster and faster.
I think the measurements of the early Universe Measurements 68 KM/SEC/MPC & Late Universe Measurements 72 KM/SEC/MPC maybe perfectly balanced as components of a working universe a sum of four units separates the two tallies. Four dimensions is an example of components that sum to a tally of four. Interesting conversation.
Is math discovered or invented… the next topic for Brian Greene?
Furchtbar die AI😂
Brian, could you do a program on Quantum Computers and AI – how they will affect the work of Theoretical Physics? Will it speed up the research timelines and create new paradigms for String Theory and other theories?
On the Hubble Tension, the Cosmic Microwave Background Radiation happened 380K years after the big bang. But the matter universe at that time is thought to be about 43M light years across or just 22M light years as a radius. So this matter expanded at something like 58 times the speed of light on average over those 380K years. In the 18.4 billion years after this time, the universe has still expanded to 46 billion light years across or 1.25 times the speed of light. Dark Energy and Inflation is real. Space is expanding or the speed of light has varied over time.
Brian plzz tell me where you got the artwork behind you.!!!!!
Using logical extrapolation, wisdom-seekers can prove the existence of the multiverse via the following cogent argument (syllogism): As our Sun is one of COUNTLESS other stars in our galaxy, and as the Milky Way is one of COUNTLESS other galaxies in this universe, so this universe must be one of COUNTLESS other universes—the ETERNAL MULTIVERSE. Alleging that the natural sequence (Sun, stars, Milky Way, galaxies, this universe, the multiverse) ends with our own universe amounts to a bias akin to anthropocentrism.
As discussed in “The Forever Balance,” 1 of the 59 essays in ATHANASIA: HUMANITY ACROSS THE MULTIVERSE, despite the fact the above syllogism isn’t testable or falsifiable, it is true because it uses self-evident facts and because it follows logically.
@zeroonetime
The collective mind of humanity has the ability to connect the first and the last link in the chain of creation. No other creature built cars and airplanes, shuttles and computers. All begins with 0 and ends up with 0: From 0 we come to 0 we go in between vastness of nothingness, timing of the infinite. 010. We are all Biological Robots.
Incredibly fascinating conversation.
Excellent content❗ top tier information and communication
Has science got age right, or is it hypothetical figures playing with mathematics. Example from the Dinosaur encyclopedia. Coelophysis from the Triassic period, a shape of 2 strong hind legs and small arms and long tail. Compare this to Tyranosaurus Rex with similar shape but different size. Cretaceous period. What I am implying almost 200 million years of existence, yet simular shape characteristics. Nothing much has evolved here in the shape characteristics. Enter Allosaurus, what about me ? 😢😂😅😊
Loved that closing on Wigner’s musings and seeing you two disagree. For whatever it is worth, I think math is discovered. Believing that a hairless monkey could come up with such an elegant way of describing the Universe appears to be too much, at least to me.
And being discovered, it gives me hope, when we find other intelligent life out there, that we could talk in Math, even if everything fails. They may use color (a la Arthur C. Clark) or infrared or some other way of communicating, but if they know Math, we will be able to talk.