Boltzmann Brain Paradox :/

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Hi guys. I'm new here and pretty much a layman when it comes to physics and astronomy.

I came across this hypothesis a few months ago, but have been looking at it the last few days.

Anyway, I'm hoping you guys know about this so you can help me. Search wikipedia for it if not. I'm not going to go into detail about what a Boltzmann Brain is.

So, my thoughts on this is that while all the articles on Boltzmann Brains always say that it is much more likely that we are Boltzmann Brains than living in our low entropy universe, I don't agree with this. The thing is though, that I've read numerous discussions and I've never heard one reason why people don't believe that this is the case, even though the physicists behind this problem say it is much more likely. In fact the only place I've read something against this hypothesis is on the wikipedia.

My thoughts are that the people who are working out the probabilities are not taking into consideration that the universe, although starting as low entropy, began as very simple and unorganised particles and energy, while a Boltzmann Brain with all its experiences and knowledge intact would be a far more unlikely quantum fluctuation as it starts immediately as incredibly ordered and structured conscious biological entity. This is my very unknowledgeable viewpoint and I'm hoping you could help me on this.

Up till now, it has only been people who don't know much about the BB Paradox that have said anything like what I've written.
 

Answers and Replies

  • #3
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I don't think that anyone believes in Boltzmann Brains either, their purpose is more to indicate what is acceptable as an explanation of the low entropy start of the universe. For instance, the idea that it is due to a blip in a normally high entropy universe doesn't work.
My thoughts are that the people who are working out the probabilities are not taking into consideration that the universe, although starting as low entropy, began as very simple and unorganised particles and energy, while a Boltzmann Brain with all its experiences and knowledge intact would be a far more unlikely quantum fluctuation as it starts immediately as incredibly ordered and structured conscious biological entity.
The point is that if you think of entropy as a measure of disorganisation, then the low entropy at the start of the universe was much more organised than a Boltzmann brain, and so much more unlikely.

Of course anyone trying to persuade you that the Boltzmann brain hypothesis is correct has the problem that if it is then they don't exist - you are the only thinking being that exists and their argument is merely part of the random fluctuation.
 
  • #4
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The universe at it's singularity was much more ordered than it is now?

The point is that if you think of entropy as a measure of disorganisation, then the low entropy at the start of the universe was much more organised than a Boltzmann brain, and so much more unlikely.
So what you're saying is that due to the Boltzmann Brain problem we should be looking for alternate theories of where the universe and its low entropy start originated?

What other theories are there that are better? I've always liked the theory of the big bang being a quantum fluctuation in the quantum vacuum though, and since my brain easily understands the concepts of philosophical skepticism, it also is very easy for me to accept such things, although doing so in this case would only throw me into a spiral of suicidal depression.
 
  • #5
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Is no one going to answer my question? Please answer.
 
  • #6
Chalnoth
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The universe at it's singularity was much more ordered than it is now?
There never was a singularity. Singularities are unphysical artifacts in a theory. However, yes, the early universe was much more ordered than it is today. This is necessarily true, just by thermodynamics: entropy never decreases. Therefore, the early universe had to have a much lower entropy than the current universe.

So what you're saying is that due to the Boltzmann Brain problem we should be looking for alternate theories of where the universe and its low entropy start originated?
That's correct. Any model that predicts there to be more Boltzmann Brains than real observers is almost certainly incorrect, so we have to search for models which predict more real observers than Boltzmann Brains.

What other theories are there that are better? I've always liked the theory of the big bang being a quantum fluctuation in the quantum vacuum though, and since my brain easily understands the concepts of philosophical skepticism, it also is very easy for me to accept such things, although doing so in this case would only throw me into a spiral of suicidal depression.
You don't need to worry about not existing :) Just observe the consistency of complex objects around you, such as noticing that the color and shape of your car is the same today as it was yesterday. An imaginary universe wouldn't have such consistency.
 
  • #7
You don't need to worry about not existing :) Just observe the consistency of complex objects around you, such as noticing that the color and shape of your car is the same today as it was yesterday. An imaginary universe wouldn't have such consistency.
I have these thoughts sometimes too, that I might not exist and that everything going on around me and my relationships and human interactions are all just part of some "computer simulation" or "imaginary universe" and that none of it really matters. Those thoughts begin to drag me into a bout of depression or "realization", if you may. However, I do not want to think this, I want to exist, and I want it to matter, whatever it is. So, thanks for that point, about the consistency of the world around me, it helps to pull me back into "reality".
 
  • #8
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So, my thoughts on this is that while all the articles on Boltzmann Brains always say that it is much more likely that we are Boltzmann Brains than living in our low entropy universe,
That's not what the BB argument is. The BB argument is that if you assume that the universe came into being by some random blip in entropy, you have a problem in that it's more likely that you have a disembodied brain come into existence.

Hence that's not what happened.

My thoughts are that the people who are working out the probabilities are not taking into consideration that the universe, although starting as low entropy, began as very simple and unorganised particles and energy, while a Boltzmann Brain with all its experiences and knowledge intact would be a far more unlikely quantum fluctuation as it starts immediately as incredibly ordered and structured conscious biological entity.
That's the problem. Your brain is small. The universe is big. The odds of a complex small object coming into random existence is far higher than an unorganized large object. Your brain, as complex as it is is made up of three pounds. You can count all of the ways that you can organize three pounds of stuff. Then count the number of ways that you can organize 10^55 kilograms of stuff. The first number is much. much. much smaller.
 
  • #9
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So what you're saying is that due to the Boltzmann Brain problem we should be looking for alternate theories of where the universe and its low entropy start originated?
Yup.

What other theories are there that are better?
No clue. If we keep eliminating stuff that doesn't work, then we'll eventually come up with stuff that doesn't.

I've always liked the theory of the big bang being a quantum fluctuation in the quantum vacuum though
I really don't. Unless you can give me some details about how quantum fluctuations in quantum vacuums work, saying this is basically more or less saying "well it just happened."
 
  • #10
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I have these thoughts sometimes too, that I might not exist
The fact that you can think, means that you exist. Read Decartes.

that everything going on around me and my relationships and human interactions are all just part of some "computer simulation" or "imaginary universe" and that none of it really matters.
The second doesn't follow from the first. If in fact I've lived all my life in a holodeck, than this is reality to me, and it matters because I say it matters.
 
  • #11
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Interesting idea that what we think is our reality is in fact a huge simulation that follows predetermined laws (possibly not necessary, some simulators allow parameter adjustment during simulation, could explain a few things!) and we wouldnt know anything about it. Although I wonder what something like our reality could be simulated on or with!?
 
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  • #12
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Does anyone know where I can get an exact quote by Boltzmann stating the paradox? I would like to quote this for a philosophy paper. Right now I'm using a quote from Feynman that sums up the position but I would rather use the man himself, Boltzmann.
 

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