The search for objective reality - with Jim Peebles

Scienists have questioned how reality could agree with physical theories that keep changing. Today, concepts like dark matter and dark energy further complicate and enrich the search for objective reality.

In this talk, Peebles will draw on a lifetime of experience as a leading physicist and using cosmology as an example for this personal reflection. Discover if the concept of objective reality is meaningful.

This livestream was recorded on 13 October 2022.

0:00 Introduction
1:16 Constructions in natural science
5:13 The objective reality of the speed of light
8:32 Is all of our physics technically wrong?
13:56 The inevitability of inventions
16:52 The expanding universe
23:01 Thermal radiation in the universe
27:55 Evidence for the evolution of the universe
46:20 Acoustic oscillations in the early universe
52:06 Exciting discoveries that haven't been discovered yet

Philip James Edwin Peebles is a Canadian-American physicist and theoretical cosmologist who is currently the Albert Einstein Professor in Science, Emeritus, at Princeton University. He is widely regarded as one of the world's leading theoretical cosmologists in the period since 1970, with major theoretical contributions to primordial nucleosynthesis, dark matter, the cosmic microwave background, and structure formation.

Peebles was awarded half of the Nobel Prize in Physics in 2019 for his theoretical discoveries in physical cosmology. He shared the prize with Michael Mayor and Didier Queloz for their discovery of an exoplanet orbiting a sun-like star.

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[K_i_t_t_y]

Why is it that the first comments under a science video are always a bunch of anti-science weirdos?! Are y'all *lost*?!

[mayflowerlash]

I am no genius. But occasionally I have had ideas that I think are original, only to find a short time later that at least one other person (often with more brain power than me) has had the same idea decades before me. This is a consequence of the curiosity of human beings. We are all imagining solutions and ideas and we are so numerous that inevitably 2 or more people will have similar ideas.

[freddyjosereginomontalvo]

Awesome channel with awsome content as always say. Excellent job!!!

[marthareal]

Excellent and sage orator. Thank you for the opportunity for this most valuable insight.

[reluginbuhl]

I just don't think that this idea of multiple 'discoveries' indicates that something 'real' must have been discovered, because they were 'independently' discovered. No one person discovers anything. The 'discoverer' is standing on the shoulders of his/her predecessors and this is why many people can make the same 'discovery'. The current culture and more specifically recent research at the time inevitably leads to the last step taken to make the so called discovery. We love heros and want to claim that one or at most a few people deserve all the credit for 'discoveries', but this is just not how scientific progress works. It's a group effort.

[charlottesimonin]

Outstanding and inspiring presentation by one of the great scientists of this time. I've known of him from this association with Penzes and Wilson and the public recognition of CMB.

[pinkfloydhomer]

I am so tired of these zoom lectures instead of the ones at the Royal Institution. At least if you're allowing these subpar lectures to be part of your brand, at least have minimum requirements for audio quality of the microphone used...

[billthompson]

If this is the kind of thing you like then you'll like this kind of thing 😜

[kalimike]

Knowing the unknowable ...thats mindboggling! To see a black hole appear in the equation, and only now knowing that they "saw" a black hole... These equations can show us every still "hidden" reality of the universe! I think that is truly awesome!! ..And thank you for explaining that to my totally non mathematical mind;!! 👌🏽👍🏽👽💥💥💥

[OldFartGrows]

In my early years I was surrounded by some of the greatest minds of their generation. I was in awe of my elders who were also my care givers.
At 63, listening to this presentation, not only am I reminded of my childhood, , I find myself in such awe that has matured to reverence. I still love my seniors. Especially those who can spin a yarn sharing our path of discovery.
Thank You

[لالهوةإلالهوتي]

If the universe would be seen to expand wherever you are therefore no centre point exists does that mean no boundary exists?

[mayflowerlash]

Bruno Latour is saying that the existence of somatostatin is confirmed by observations in the laboratory and NOT by social constructs. Bruno Latour is a sociologist, and presumably knows nothing of chemistry. So far so good. Then Jim Pebbles says he will not attempt to interpret this statement, even though I think Bruno's meaning is crystal clear.

[TDOBrandano]

But does the act of examining science's social constructs affect the social constructs?

[Hugh_I]

Very interesting bits in this talk about how these discoveries where made, some of which I haven't heard about at all before. However interesting as those bits were in their own right, I am at a loss to see what most of it has to do with the framing question of the talk: whether or to what degree scientific knowledge is socially constructed. What was the actual point he was trying to make? Was all that just to say there is an objective reality and he thinks of models/theories of modern physics as approximations to that? Is that all? Because sure, I generally agree, but that's pretty broad and doesn't really say much about how or how much the way we think about this reality or with what approximations we come up with is influenced by culture/language/society. It doesn't strictly contradict what Latour says in the initial quote either, so does he agree with it or was that supposed to be an argument against that?

[smlankau]

Maxwell's equations should change because the magnetic field in them is actually an electric field. 😮

[aaronrobertcattell]

like a fish in water gets to go up down back and forwards and left and right take him out the water and everything just got bigger?

[claudiaarjangi]

To me, the expansion of space looks like a universal 'curvature' of space/ time (so not a 'flat' spacetime).. As in ( over long distances and time)
When taking time into account parallel lines don't stay parallel, they diverge ..
Triangles don't add up to 180°, like in 'flat' space..
( all of this is an open question 🤷?)☮️

[charlesbrightman]

Consider the following:
a. Numbers: Modern science does not even know how numbers and certain mathematical constants exist for math to do what math does. (And nobody as of yet has been able to show me how numbers and certain mathematical constants can come from the Standard Model Of Particle Physics).

b. Space: Modern science does not even know what 'space' actually is nor how it could actually expand.

c. Time: Modern science does not even know what 'time' actually is nor how it could actually vary.

d. Gravity: Modern science does not even know what 'gravity' actually is nor how gravity actually does what it appears to do.

e. Speed of Light: 'Speed', distance divided by time, distance being two points in space with space between those two points. But yet, here again, modern science does not even know what space and time actually are that makes up 'speed' and they also claim that space can expand and time can vary, so how could they truly know even what the speed of light actually is that they utilize in many of the formulas? Speed of light should also vary depending upon what space and time it was in. And if the speed of light can vary in space and time, how then do far away astronomical observations actually work that are based upon light and the speed of light that could vary in actual reality?

[samadams]

That's all very well and good but the red shift can also be accounted for by the concept of the variable light speed theory. Speed of light at one time was considerably faster than it is and has dropped and would also result in the appearance of a red shift. The beautiful thing about that is you don't need to have the universe expanding, no hyperinflation where you have to make believe that space travels faster than the speed of light and it's expansion and you also have the benefit of not requiring dark energy or dark matter. Combining the variable light speed theory of the universe along with modified Newtonian Dynamics or MOND, which by the way has had some recent success in terms of observation supporting it, means that we have a much more simplified explanation of the universe. Let's apply Occam's razor here shall we?

[pcuimac]

To describe Maxwell's Equations as "simple" is a real understatement. They are a theory that's compatible with Einsteins special relativity equations long before Einstein came up with his theory and they are Tensor equations of terrible complexity and not easy to calculate at all. The integral versions are not easy either.