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Chadmartigan t1_iu0nek5 wrote

tl;dr: Spacetime is not fundamental because all particle dynamics are projected/encoded in spacetime by a sort of platonic object that exists outside of spacetime. Put differently, all the dynamics we observe (or more precisely, their scattering amplitudes) can be mapped to a mathematical object (the Amplituhedron). So what Hoffman is proposing is that spacetime (including I assume the objects within it) is not fundamental because spacetime (and everything in it) is encoded by some more fundamental object that exists somewhere else.

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L0nely_L0ner t1_iu15m3a wrote

I wish I could be smart enough to undertand it, haha.

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Chadmartigan t1_iu1e244 wrote

Well, it's absolutely unintuitive. It's helpful if you understand where Donald Hoffman is coming from. He's a cognitive psychologist who has spent most of his career studying perception and consciousness down to the "what IS reality" level.

Hoffman's general premise is this: the world as we know it--the senses and observations and even the thoughts we have about them--aren't really reality. They are approximations of reality constructed by our brain, which serves the function of an evolutionary advantage. In other words: our perception of the "real" universe is a highly abridged, compressed, and edited slice of reality.

The actual, objective reality is whatever is going on with quantum mechanics, relativity, et al. We obviously don't see/touch/smell all of that. Those things work and function in ways that--while highly organized and predictable scientifically--are almost totally unintuitive to any human being. And surely Hoffman is right about that much.

This article asks the reader to take one more upward step of abstraction. Just as the "reality" we perceive is an abridged and smoothed-out shadow of the particles and systems all around us, Hoffman proposes that all those particles/systems/bodies/forces we observe in spacetime are all, themselves, "projections" of some mathematical object. In that case, the "fundamental" core of reality isn't spacetime or anything in it, but something else entirely, that exists (at least mostly) outside of our 4-dimensional spacetime.

The mathematical object in this case is known as the Amplituhedron. In simple terms, this is a geometrical object in which the constituent points describe particle interactions. Prior to 2005 or so, the math to do the calculations for very simple particle interactions was very labor-intensive. (Think hundreds of pages of calculations for a system with fewer than ten particles.) But with the discovery of this Amplituhedron method, those calculations could be greatly simplified.

Now, we could debate all day about whether this Amplituhedron is "real" or not. But that's kind of semantic. Whether it's real or not, the science points to a deep mathematical structure underlying spacetime. Hoffman's argument is that that structure is what's fundamental. Everything we observe is just a constituent part of that object brought to life in spacetime.

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L0nely_L0ner t1_iu1emob wrote

Wow. You made it almost 100% understandable even to a simpleton like me, haha. Thanks for your work!

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fullawe t1_iu3jbdj wrote

I think in the same way that the mathematical existence of the Amplituhedron implies the existence of a deeper layer, so does the big bang.

An event happened that caused the big bang and all that comes after. Therefor there was something beforehand.

If one event can happen, another may as well. I hope we find structures within the CMB. I think it would show that our universe was born inside another.

Perhaps others could be born inside ours, with their initial inflation showing as late inflation to us.

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Chadmartigan t1_iu4t5iy wrote

IMO, if we find total randomness in the CMB, that's just as interesting.

The deep structure is what makes theories like Conformal Cyclical Cosmology more compelling for me. The idea there is that the conditions of the late-stage universe (post-mass-decay and black hole evaporation) conform to those of the earliest moments of the big bang in all regards except the scale of the space. In other words, if you take the late stage universe and squeeze down the scale of spacetime, you get the something that looks a lot like the early big bang. And if Penrose is right, that might not be such a difficult hurdle to overcome, since scale and space kind of fall out of the picture in the late-stage universe anyway, and there's no particular reason it should be strictly preserved from one aeon to the next. (Some information within spacetime could be preserved, however - notably gravitational waves should survive from one aeon to the next, and perhaps some radiation as well.)

If all this is right, even just kind of conceptually right, that would point to a structure underlying the "reality" of spacetime that is preserved from one universe to the next.

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fullawe t1_iu5w2c3 wrote

It was cyclical cosmology that lead me into my idea. The change of scale at absolute entropy is a cool idea.

I think we should be trying to find solutions that aren't cyclical though. Although that doesn't mean that spacetime isn't preserved.

Another thought I had was to split space/time. In that, time started at the moment of the big bang, and is tied to space in a direct correlation of 1:1.

Space would be preserved throughout universes, but not time. I believe that the implication is that time can be tied to the speed of light across a unit of spac. That all non baryonic particles can be unified into a single field, that excludes gravity.

Gravity becomes an artifact of the deeper level of emergent space, and the expansion of our universe becomes the potential energy of each subsequent big bang being realised.

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eag97a t1_iu3ng4m wrote

Basically math is reality, Max Tegmark surely would be very happy…

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100GHz t1_iu22t7a wrote

A banana is not a fundamental energy food.

It is not the banana that gives us energy, but something from which banana is made.

We can see bananas, taste them, smell the various kinds, but deep down there, all bananas are made of something else that gives us energy when we eat it.

Some propose Earth wind and fire.

Some propose Tasty Bits.

Some propose ideas that Gods forge into reality.

Cue the invention of the microscope. The game moves one level down: a banana is made of cells.

Before the microscope, people had all sort of theories, after that, well, cells.

But what are banana cells made of?

Repeat this few times and that's where we are. Banana is now made of tiny energetic stuff flowing in time interacting with other stuff. But, that's as far as we can observe/prove/derive.

What is below this level, well why, a very fertile land for research grants, and everybody having a take on what a banana is actually made of.

Source: a banana

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