Susskind says Universe is not Real

Another respected physicist has gone off the deep end. In a new video:

Why the Universe Is Not Real | Leonard Susskind

At first glance, the idea sounds absurd. The universe feels undeniably real. Galaxies exist. Space stretches outward. Matter occupies locations and evolves over time. How could the universe not be real?

In this video, we explore what physicists actually mean when they challenge the reality of the universe. “Not real” does not mean “does not exist.” It means something far more precise — that the universe we experience may not be fundamental. ...

0:00 The universe is not real. I know how that sounds. It sounds like philosophical nonsense, like something a stoned undergraduate would say at 3:00 in the morning. But I'm serious. After spending decades studying quantum mechanics, black holes, and the foundations of reality, I've come to a conclusion that would have shocked my younger self. The universe, as we experience it, is not fundamentally real.

He gives several arguments: (1) Schroedinger Cat is dead and alive simultaneously; (2) We only see one world of many-worlds theory; (3) Physical states are sometimes determined by a boundary condition, so we are a hologram; (4) At the Planck scale, quantum gravity teaches that spacetime breaks down; (5) Observations depend on what observers do.

Let me connect this to black holes again 13:16 because that's where these ideas become most concrete. When you fall into a black hole, you experience crossing the event horizon smoothly. From your perspective, the interior is real. You fall through space toward the singularity. But from the perspective of someone outside, you never cross the horizon. You appear to freeze at the horizon. ...

The fundamental 14:03 reality is the quantum state of the black hole,

He ends up concluding that the universe is not real. So what is real? The Tegmark mathematical universe and consciousness.

20:09 Everything you think is real, solid, definite, is actually quantum, abstract, probabilistic at the fundamental level. The classical reality is an illusion your brain constructs from quantum information. The universe is not real in the way you think it is. It's something uh far stranger. ...

Love is an emergent 21:23 phenomenon arising from brain chemistry, from evolutionary psychology, from social structures. Does that make it less real, less valuable? Of course not. ...

The 23:22 universe is not real in the naive sense. And that's one of the most important discoveries in the history of physics. It changes everything about how we understand reality and our place in it. ...

The universe is not real. 24:14 And that's the most profound truth about reality I've ever discovered.

He is a good illustration of how modern physics has gone wrong.

The Golden Age of Phyics was 1860-1935. Then everyone idolized Einstein for his foolish pursuit of unified field theory and rejection of quantum mechanics. Theoretical physicists studied quantum gravity, nonlocal interpretations, strings, holograms, black hole firewalls, many-worlds, landscape, etc., all to no end.

Susskind went through phases supporting all that stuff, and ends up denying reality.

He is now firmly in the existential crisis iceberg. Accepting what he says is the same as saying we live in a simulation, or that reality is a dream.

All his favorite theories -- hologram, many-worlds, Tegmark math universe -- leave no room for free will or scientific inquiry. He denies that it is nihilism, but that is exactly what it is. We are worse than rats in maze.

He goes wrong at the start, with the Schroedinger Cat. The Cat is just a simple example of uncertainty about two possible events. There is no deep math or physics involved. A child can understand that he might not know what is in a box. But it is very strange to make the leap from that to saying that the universe is not real. I do not think that I could convince a 4-year-old of that.

Susskind also has a new video:

Why Objects Don’t Really Exist | Leonard Susskind

Objects feel like the most basic elements of reality. Tables, chairs, planets, particles — the world appears to be built from things. It seems obvious that objects exist. But modern physics tells a very different story.

In this video, we explore why objects may not be fundamental at all. “Don’t exist” does not mean imaginary. It means that objects are not the deepest level at which reality is defined.

He talks about cats, fuzzy objects, ships with boards replaced, entangled particles.

Another video says:

Why Time Is a Byproduct | Leonard Susskind

We usually think of time as one of the most fundamental ingredients of reality. Everything seems to move through time. Causes come before effects. The universe appears to unfold moment by moment along an invisible timeline. But modern theoretical physics suggests a very different picture.

In this video, we explore the unsettling idea that time may not be fundamental at all. Instead of being the engine that drives reality, time may be a byproduct — something that emerges from deeper processes rather than causing them.

And another new video says black holes are not real:

Black holes are usually imagined as objects with a deep, hidden interior — a place where matter falls and disappears forever. This image is deeply ingrained in popular science. But modern theoretical physics suggests something far more surprising: black holes may not have an interior in the way we think.

In this video, we explore why physicists increasingly question the idea of a black hole interior. “No interior” does not mean nothing happens when something falls in. It means that the information describing that object is not stored inside the black hole as an internal structure.

He says he spent years trying to convince Hawking that if you throw a book into a black hole, then the information will eventually bubble out the surface. His main argument that there is no interior is that if the book fell down to the center, then it is hard to see how the info would ever get out.

He can get away with saying anything he wants about a black hole interior, because it is not observable. But he gets totally wacky and says wormholes are the same as quantum entanglement.

I see now that Susskind has just put out a lot of these videos. Have fun listening to erudite nonsense.

On second thought, I think I have been duped by AI slop. These podcasts have Susskind's voice and his his opinions, but they are more forcefully and coherently argued than he does in real life. I think some AI has scanned his lectures and writings, and made them more intelligible.

I semething similar with Roger Penrose. See Quantum Mechanics Is NOT Random. It is a very good summary of Penrose's view on the subject, and rendered in his own voice. Here is another on Gravity Isn't Pulling You Down — The Ground Is Pushing You Up, and one on Einstein Was Right: Past, Present & Future Are An Illusion — Here's The Proof.

These podcasts are the future of education, I am afraid. They are better than the real Susskind and Penrose, and faithful to their opinions and voices. Maybe we will not have live lectures anymore. Someone will give several lectures on a subject, and then an AI will distill, refine, and polish the material into a better lecture.

Getting back to the original topic, Susskind is not real. He is an AI reconstruction.

Has quantum advantage been achieved?

Dominik Hangleiter writes on his blog:

Recently, I gave a couple of perspective talks on quantum advantage, one at the annual retreat of the CIQC and one at a recent KITP programme. I started off by polling the audience on who believed quantum advantage had been achieved. Just this one, simple question.

The audience was mostly experimental and theoretical physicists with a few CS theory folks sprinkled in. I was sure that these audiences would be overwhelmingly convinced of the successful demonstration of quantum advantage. After all, more than half a decade has passed since ...

I could not have been more wrong.

In both talks, less than half of the people in the audience thought that quantum advantage had been achieved.

No, quantum supremacy has not been achieved, if most experts are not convinced. The whole was to do a public demonstration that convinces everyone that quantum computers are possible.

Dr. Bee Revives Nonlocal gravity

Sabine Hossenfelder posts a new video:

0:38 The laws of physics that we have discovered have one thing in common: they are local. This means that objects in two different locations cannot interact with each other. They don’t know anything of each other. ...

A bit like theorists and experimentalists. 0:53 It is only by sending some sort of signal from one object to the other that they can react to each other’s presence. We have no idea why the laws of nature are this way. There’s no particular reason why they should be. It’s just that it corresponds to our experience.

I would say that there are reasons. Locality is the whole basis of scientific reductionism. It allows us to do controlled experiments. Without it, we could never make sense out of the world.

Also, it is all a consequence of the non-euclidean geometry of spacetime.

1:09 Newtonian gravity is not local, this bothered Newton a lot back then. You see if you take Newton’s law of gravity, with the gravitational force proportional to the mass divided by the square of the distance, then if you move the mass, the distance increases and the force changes instantaneously, everywhere. Newton was greatly bothered by this. He called it “action at a distance” and that’s also what Einstein meant by the phrase.

1:39 Einstein’s theory of general relativity, which we use now to describe gravity, doesn’t have this problem. In Einstein’s theory, gravity is described by the curvature of space and time. And that curvature is caused by the mass and energy in spacetime. If you move the mass that causes spacetime to curve, then the curvature changes, but not instantaneously. The change spreads outwards at the speed of light

Actually it was Poincare who figured out that gravity propagates at the speed of light. Einstein did not accept or believe it.

And this nonlocal gravity just seems to do it. 4:18 Better still the idea that gravity isn’t entirely local is something you’d expect to naturally occur in a theory of quantum gravity because we know that quantum physics isn’t local. I really like the idea.

No, this is crazy talk. Quantum physics is just as local as general relativity. In cosmology, you could have a couple of orbits that are correlated, so that knowledge of one tells you something about the other. That's all people mean by quantum nonlocality.

A reader will surely say that no, quantum nonlocality means that a correlation could be quantitatively greater that what a believer in an alternative theory might expect. Yes, that is true, but it does not have a bearing on whether a theory is local or nonlocal.

In another video, she endorses the Einstein block universe.

Maybe this video more than anything explains why I've always been a bad 11:30 fit for academia. Because what really is this? Is it philosophy? Is it physics? It's neither here nor there. Yet for me, questions like this are the reason I studied physics because I want to understand how the universe works.

Academia has no need for her twisted ideas about how the universe works.

Elsewhere she expreses a belief in superdeterminism, but that contradicts some of what she says here. Maybe she has abandoned superdeterminism, but she ought to explain it.

quantum 9:43 physics has an indeterministic unpredictable element which is what happens the moment one makes a measurement. ... There seems to be a difference between the past and the future in quantum mechanics.

Most of the video is an argument that Einstein's relativity requires us to believe in the block universe, where the future is as real as the past. She says different coordinates are allowed, and so the meaning of "now" can be different for different observers.

This is a misunderstanding of relativity. Einstein was a determinist, and did believe in the block universe, but most physicists do not.

Yes, relativity does allow different coordinates, but that does not mean you have to accept another "now", or that the future is determined. Most physicists accept that the CMB radiation defines a universal now, without contradicting relativity.

Even if I accepted that there is no universal "now", and that my future is already in a past coordinate system for some other observer, it would not follow that my future is determined. She defines "now" by coordinate lines, not light cones, so an observer does not even see what is now for him.

Dr. Bee talks about many science topics outside her expertise. These two videos are squarely within her expertise, so I expect better.

Cantor's Diagonal Argument

Cantor's diagonal argument is famous for proving the uncountability of the real numbers. It is not so well known that Cantor's first set theory article proved it differently.

Here is the proof. First of all, we need to assume the completeness of the reals, in some form.

Theorem. If { A_k } is a collection of compact nested subsets of R, the real numbers, then the intersection is nonempty.

Compact means closed and bounded, like the interval [0,1], including the endpoints. Nested means each contains the next. The proof depends on how you have defined R. For example, you could get an intersection point as the least upper bound of the left endpoints.

This is a way of expressing the completeness of the reals. If we used the rationals instead, then we could have nested intervals about √2, and the intersection would not include any rational numbers.

To prove uncountability, suppose we have an enumeration { x_k } of R, and we seek a contradiction. We define a collection { A_k } with x_k not in A_k, and apply the theorem to get a real number in all the sets, and hence not in the enumeration.

Start with [0,1]. Let A₁ be a closed interval subset excluding x₁. Eg, if x₁ = 0.4, then A₁ could be [0,.3] or [.5,1]. Likewise, let A₂ be a subset of A₁ that excludes x₂, and so on, and thus A_k excludes x₁,..., x_k. Applying the theorem gives at least one real in all of the intervals, and hence not part of the enumeration.

This is really a diagonalization argument, and maybe less intuitive, so what's the point?

I like it better. The usual diagonal argument is deceptively simple, as it assumes facts about the reals, such as every decimal expansion converging to a real, and reals having unique decimal expansions, with certain exceptions. This is still a diagonal argument, gets more directly to the heart of the matter, and explicitly uses the completeness of the reals, without the distracting decimal expansions.

Cantor gave a similar diagonal argument to show that the cardinality of a set A is less than the set P(A) of all its subsets.

Suppose not, so that there is some onto function f: A -> P(A). That is, where f(A) = P(A). Then let B = { a in A : a not in f(a) }. If B = f(b) for some b in A, then b is in f(b) if and only if b is not in f(b), a contradiction. Thus the image of f cannot be all of P(A).

This shows that taking all subsets always gives a set of larger cardinality.

Scott Aaronson recommends a video on Cantor's diagonal argument.

Wild Enthusiasm for Quantum Computing

This new interview makes a lot of big claims for quantum computing:

Q-Day — when quantum computers crack all encryption — is coming. Quantum eMotion COO John Young breaks down the pros and cons of what’s to come.

It is all ridiculous. I could not even bear to listen to the whole thing.

I have gotten used to this sort of enthusiasm for AI. But a 100 million people use AI everyday. Quantum computing has very little hope of ever accomplishing anything.