Why The Universe Doesn't Exist - Only Your Brain!

Boltzmann brains are perhaps one of the spookiest ideas in physics. A Boltzmann brain is a single, isolated human brain complete with false memories that spontaneously fluctuates into existence from the void. They're the kind of thing you'd find in a campfire horror story. The big problem, however, is that a range of plausible cosmological models (including our current cosmology) predict that Boltzmann brains will exist. Even worse, these brains should massively outnumber "ordinary" conscious observers like ourselves. At every moment of your existence, it is more likely that you are an isolated Boltzmann brain, falsely remembering your past, than a human being on a rocky planet in a low-entropy universe.

In this video I explain where the idea of Boltzmann brains originated, and why they haunt modern cosmology.

Thanks for watching, and I hope you enjoyed! Please like and subscribe for more videos on amazing ideas in physics.

[chinmaykrishna]

I am extremely happy to see this channel grow! Whoever you are, your explanations are simply great. I was here from the time you had about 5 subscribers. I am grateful to the YouTube algorithm for recommending this channel to me!

[smolboi]

The assumption is that we start off in a highest entropy state and hence such packets of low entropy space is so unlikely. We could have started of in a very small entropy state.

[thestoneyjabroni]

This was the fourth video on Boltzmann Brains that I've watched because I couldn't really follow the way the other videos explained it. But this was clear and concise. Very well explained.

[junacebedo]

God is telling us- "You need ME or else thou art a Boltzmann's brain"

[BM-jycb]

I love the idea of a Boltzmann brain - it's such a logical conclusion and, as far as I'm aware, no-one has disproved it with the only argument against it being that it doesn't feel right - an argument that physics has shown to be naive many times before. BTW, subscribed - you deserve a lot more views than you're getting. Glad to see you've rebooted the channel and I hope you get the growth it deserves.

[bobrussell]

Brilliant Video. Thank You. I've subscribed !

[NightmareCourtPictures]

Part of me wants to form the argument that the Boltzmann Brain is a more logical form for the universe to take. It makes sense when you think about thermal equilibrium and statistical fluctuations.

But I like to think about what the purpose of it would be.

For example: I think many would agree with this; and consider entropy as an optimization process for measuring the shape of some geometry. Imagine you have a polygon floating in a space that has yet to be decided on how many sides or vertices it has. Throw a bunch of balls with laws of physics into the space from inside that shape, and eventually the particles will approximate that shape as it approaches thermodynamic equilibrium.

So once you've already approximated this shape at thermodynamic equilibrium, what is the point of the balls and the fluctuations past that? To me this sounds like a Turing completeness, or computational complexity problem. You've got these balls in a space that made a computation (approximating the size of a shape) but now these balls can approximate other shapes...do math problems and essentially do Turing complete computation.

If we are truly Boltzmann Brains, and not real observers then it would point to this idea that computation is a fundamental thing...and not some auxiliary law...Because computation simply exists as a product of having balls moving in a space...

Those balls after they've completed the approximation of that shape, can go on to make approximates of a near infinite number of other shapes and problems so long as they are problems with the same computational complexity. The beauty in that is that the balls don't have to be inherently random (quantum) either...in fact a completely deterministic system does and can do the same thing thanks to chaos theory.

People talk crap about Stephan Wolfram, but more and more everyday i believe that he is on to something that physicists are completely overlooking. His computational models make a lot of sense to answer these paradoxes...he just merely built a foundation but i think if physicists gave him a chance, they would make some real progress and move towards a more computational model of the universe.

[lemmetellyousomething]

What if the physics is nowhere near as we know it to explain the possibility of Boltzmann brain outside of the Boltzmann brain..?

[BrettonFerguson]

When you factor in all the LSD I took between 13 and 16 years of age, the odds I'm just hallucinating everything right now, goes way up.

[fLaMeProF]

I think maybe Boltzmann failed to consider the mathematics of emergent information; i.e. diminishing information pathways with increasing complexity which can evolve as a natural part of some function... Consider fractals - as you iterate a fractal function and express the output geometrically, the 'empty' space increases, but in the diminishing areas where structure/information exists, the complexity of that information increases at smaller scales

I guess Boltzmann didn't know about fractal geometry or chaos theory....

So, rather than thinking about massive low entropy states suddenly springing into existence, rather consider *mathematical processes* by which complexity can evolves from seemingly simple low entropy states / functions... This is how procedural generation is put to work in games, resulting in fractal universes... Is it a coincidence that our own universe appears to be fundamentally fractal in nature?

In this mode of thinking, it is altogether reasonable to suggest that the *evolution* of an entire universe containing brains, as an evolving multi-dimensional fractal information pathway, is more probable than even a single brain, with all of it's complexity, springing into existence by chance within the void...

Neural networks are fundamentally quite simple structures, and indeed as we look around our natural world and the wider universe we see plenty of evidence that the natural evolution of such structures is somehow fundamentally writ within the cosmos at both micro and macro scales. Perhaps consciousness itself was somehow encoded within the initial super-low entropy state of the big bang? (I tend to apply the strong anthropic principle here and say it must have been!)

[Alan-zftt]

Just discovered your channel and appreciate the wavelength you are on by questions you ask.
A great channel.
Observations
What constrains possibilities into being probabilities? For example it is possible for a needle to balance on the sharp pointy bit but highly improbable. Why?

Science n math seem to observe things then build models to explain why those things happen. In other words reality always trumps model. If a model says one thing and reality does another what can be deduced?

Infinity and infinitesimals. They certainly exist in science and math models/theories but in reality is there such a thing as infinity? Maybe a constraint on "infinity/infinitesimals" is Planks's constant? Do infinitesimals really break discrete/continuity assumptions in modelling?

[Purple_Freedom_Ninja]

Things get seriously wild when we assume there's no creator

[xxnotmuchxx]

No one talks about the possibility that the universe is a Boltzmann brain like omega point.

[bariole]

I don't think that argument presented here, against Boltzman brain is well developed. It argues that creating a brain from statistic fluctuations of low entropy system is more likely than creation or star - "because deviation from entropy average for a star is far larger than for a brain, than it is more likley that brain will occur than a star."

Well that is correct only when: a) it is not any star, but THIS star against THIS brain and both were created by MAGIC, and b) ignores the rest of natural laws which drive evolution of system.

My understanding of Boltzman brain is that statistical fluctuation will put the system (phase space) in a place of big enough entropy difference that Work is now possible (any energy flow will do). After establishig that, Laws of Nature will evolve both stars and brains. Both are product of evolution of optimising energy flow, however as stars are much less complex system to evolve there will be more of them.

[Obi-Tod-Kenobi]

Ever since I was a child, I've always had this feeling that a lot of this theory is true, however, I was totally unaware of the theory obviously.

I just think it is all mind, there is no matter. Because of this one logic... I would have I've made the same decisions you made if I lived your life and vice versa. Ever since I was a kid I just couldn't shake that thought and only gone further down that rabbit hole.

The universe could have never existed but it did and it didn't start, It always existed something that we can't comprehend and never will. But I am pretty sure we will just continue to wake up as if from a dream.

[tact]

Really convoluted argument to hint at an exterior mechanism we can’t detect

[aerynleighproductions]

surfed in here from the comment section of talking about Boltzmann Brains/Universes. I'm already having a semi-crisis from *that* video and now this -- another thing to be lying awake at 3am for. Perhaps the Boltzmann model answers the Fermi paradox. Damn. Anyways great explanation, loved the whiteboard ha.

[ibperson]

Great job!!!! More recently some are saying that the list of fine tuned constants (AND initial values, like the ratio of matter and antimatter) has gotten so long that just having the values necessary to have a remotely coherent universe is less likely than a boltzman brain. So saying there is a multiverse and we necessarily find ourselves in the one where higher elements and stars can form (anthropic principle) is countered with “it’s less likely to land in that universe in the multiverse than to be a boltzman briain. Check out leonard susskind fine tuning and on channel closer to truth. The amount of finr tuning we realize had only increased since that video

[vapormissile]

If there is a Heaven (and God, I hope there is) then I hope there is a 10-dimensional Boltzmann Heaven. Or a regular Heaven. Whichever.

And there will be animals there. It'll be awesome.

[BrettonFerguson]

Shit I missed where all the swastikas around Earth came from.