but it does depend on assumptions such as that the universe is eternal — wonderer1
The preponderance of evidence to date, based on measurements of the rate of expansion and the mass density, favors a universe that will continue to expand indefinitely, resulting in the "Big Freeze" scenario below.
The heat death of the universe, also known as the Big Freeze (or Big Chill), is a scenario under which continued expansion results in a universe that asymptotically approaches absolute zero temperature. Under this scenario, the universe eventually reaches a state of maximum entropy in which everything is evenly distributed and there are no energy gradients—which are needed to sustain information processing, one form of which is life. This scenario has gained ground as the most likely fate.
In this scenario, stars are expected to form normally for 1012 to 1014 (1–100 trillion) years, but eventually the supply of gas needed for star formation will be exhausted. As existing stars run out of fuel and cease to shine, the universe will slowly and inexorably grow darker. Eventually black holes will dominate the universe, which themselves will disappear over time as they emit Hawking radiation. Over infinite time, there could be a spontaneous entropy decrease by the Poincaré recurrence theorem, thermal fluctuations, and the fluctuation theorem.
This isn't just an assumption. Rather:
— Michael
The preponderance of evidence to date, based on measurements of the rate of expansion and the mass density, favors a universe that will continue to expand indefinitely, resulting in the "Big Freeze" scenario below...
BB speculations are scientifically self defeating. — wonderer1
Given the bigger picture, resulting from empirical observations considered more broadly, the evidence points towards us being the result of biological evolution. Do you think the majority of physicists would disagree? — wonderer1
The consensus amongst cosmologists is that some yet to be revealed error is hinted at by the surprising calculation that Boltzmann brains should vastly outnumber normal human brains. Sean Carroll states "We're not arguing that Boltzmann Brains exist—we're trying to avoid them." Carroll has stated that the hypothesis of being a Boltzmann brain results in "cognitive instability". Because, he argues, it would take longer than the current age of the universe for a brain to form, and yet it thinks that it observes that it exists in a younger universe, this shows that memories and reasoning processes would be untrustworthy if it were indeed a Boltzmann brain. Seth Lloyd has stated, "They fail the Monty Python test: Stop that! That's too silly!" A New Scientist journalist summarizes that "The starting point for our understanding of the universe and its behavior is that humans, not disembodied brains, are typical observers."
Some argue that brains produced via quantum fluctuation, and maybe even brains produced via nucleation in the de Sitter vacuum, do not count as observers. Quantum fluctuations are easier to exclude than nucleated brains, as quantum fluctuations can more easily be targeted by straightforward criteria (such as their lack of interaction with the environment at infinity).
Carroll believes that a better understanding of the measurement problem in quantum mechanics would show that some vacuum states have no dynamical evolution and cannot support nucleated brains, nor any other type of observer. Some cosmologists believe that a better understanding of the degrees of freedom in the quantum vacuum of holographic string theory can solve the Boltzmann brain problem.
Brian Greene states: "I am confident that I am not a Boltzmann brain. However, we want our theories to similarly concur that we are not Boltzmann brains, but so far it has proved surprisingly difficult for them to do so."
So if the world around me is somehow a construct of my mind, it is very different to other mental constructs. — Banno
So different that one might be tempted to call it "real"? — Banno
No, it doesn't, but it might reduce the solipsist to the status of a mere object of ridicule. — Banno
That is, in both these cases, as in the case of the existence of the world, there may be a point at which one's credulity is strained a bit too far. That point will be different for different folk, some of whom never participate in philosophy fora, some who treat it as an amusement and a very few who take it seriously enough to find themselves in an asylum.
So perhaps all up it is not unreasonable to take things at face value? — Banno
Solipsism is a philosophical idea. It is a language construct. — creativesoul
Solipsism cannot be defeated with certainty, but it is defeated by plausibility. You say, "in the case that I think there is no world", but no one or almost no one thinks that due to its implausibility. The issue of solipsism only gets raised because we cannot be, as with many other things, absolutely certain it is not the case. — Janus
The OP was not edited at all. But due to misunderstanding of many folks in their posts (including Banno), there had been extra posts added by me for clarifying and broadening the OP into any possible exploratory discussions on the elementary concepts in the OP title as well as general epistemological, sceptic, ontological and logical issues in perception.In any case, I remember this thread being about solipsism, but it seems the OP was edited to mean something more like object permanence and the problem of induction, or perhaps I misread the first time. — Lionino
Why? They're entailed by our best scientific theories. — Michael
Is it possible that you and your surrounding environment, including all of your purported knowledge of the past and the outside world, randomly fluctuated into existence out of a chaotic soup of particles? Sure, it’s possible. But you should never attach very high credence to the possibility. Such a scenario is cognitively unstable, in the words of David Albert. You use your hard-won scientific knowledge to put together a picture of the world, and you realize that in that picture, it is overwhelmingly likely that you have just randomly fluctuated into existence. But in that case, your hard-won scientific knowledge just randomly fluctuated into existence as well; you have no reason to actually think that it represents an accurate view of reality. It is impossible for a scenario like this to be true and at the same time for us to have good reasons to believe in it. The best response is to assign it a very low credence and move on with our lives.
The general gist seems to be:
1. our scientific theories suggest that we are most likely Boltzmann brains
2. we are not most likely Boltzmann brains
3. therefore, our scientific theories are mistaken
The point I am making is that, by this very argument, (2) is not supported by the scientific evidence. Rather it's something like "common sense" or "intuition" or "faith". — Michael
I'm then asking if it's reasonable to favour common sense, intuition, or faith over scientific evidence. — Michael
Of course, if you admit that we can sometimes be justified in believing that the scientific evidence is mistaken then you open yourself up to arguments for idealism or theism, as it would certainly be hypocritical, or special pleading, to argue that we must believe in an external material world because there is scientific evidence for it but that we must not believe that we are Boltzmann brains even though there is scientific evidence for it. — Michael
Is it possible that you and your surrounding environment, including all of your purported knowledge of the past and the outside world, randomly fluctuated into existence out of a chaotic soup of particles? Sure, it’s possible. But you should never attach very high credence to the possibility. Such a scenario is cognitively unstable, in the words of David Albert. You use your hard-won scientific knowledge to put together a picture of the world, and you realize that in that picture, it is overwhelmingly likely that you have just randomly fluctuated into existence. But in that case, your hard-won scientific knowledge just randomly fluctuated into existence as well; you have no reason to actually think that it represents an accurate view of reality. It is impossible for a scenario like this to be true and at the same time for us to have good reasons to believe in it. The best response is to assign it a very low credence and move on with our lives. — Sean Carroll
There are lots of theories outside of physics that have a lot of evidentiary support as well. — wonderer1
1. If we are not Boltzmann brains then we can trust our scientific knowledge
2. Our scientific knowledge strongly suggests that we are most likely Boltzmann brains
3. Therefore, if we are not Boltzmann brains then we are most likely Boltzmann brains
There's certainly some "cognitive instability" in his position, too. — Michael
How about a Boltzmann universe? — Michael
I was presenting the inverse of his argument to show that his position suffers from that same cognitive instability. — Michael
I think the difference you are trying to draw is between a voluntary and an involuntary construct. — Lionino
Agreed, we cannot be 100% sure of most things, or perhaps any. Though to rule something as less likely we need some successful arguments against it, I am pointing out that many of the arguments raised in this thread are not successful as they seem. — Lionino
it doesn't explain how a random fluctuation like a Boltzman brain could come up with consistent and coherent scientific theories that show that it is most likely a Boltzmann brain — Janus
The way I see it is that something should be thought to be less likely if it is less plausible in light of our experience, less consistent with that experience, and to my way of thinking solipsism seem way less likely, in fact improbable in the extreme, in light of that experience. — Janus
Which arguments in this thread do you see failing and on what basis do you assess them as failures? — Janus
I didn't see what the memory question was. — Lionino
That works in practical everyday life. But if we are to go by that, we would simply do away with the problem of induction, for one; we would do away with so many things that are still considered worthwhile in philosophy. Experience is not the goal to end all goals. — Lionino
All the ones I rebutted to and that at the end of the discussion I did not acquiesce to the person's point. — Lionino
His argument is if P, not Q (if we are Boltzmann brains, we cannot trust our scientific knowledge); you showed how {if not P, Q} (if we are not Boltzmann brains, we can trust our scientific knowledge) entails a contradiction. How does that show his position has the same issue? — Lionino
But in that case, your hard-won scientific knowledge just randomly fluctuated into existence as well; you have no reason to actually think that it represents an accurate view of reality.
It's right there in that post you responded to:
1. If we are not Boltzmann brains then we can trust our scientific knowledge
2. Our scientific knowledge strongly suggests that we are most likely Boltzmann brains
3. Therefore, if we are not Boltzmann brains then we are most likely Boltzmann brains — Michael
if this is so how could we trust our scientific theories, or even trust that we remember them correctly, or that they were ever really formulated? — Janus
Hume merely showed that induction is not deduction, that inductive inferences are no necessary — Janus
Is it just because they are still around, because some people are still arguing about them? — Janus
You mean all the ones you, in your opinion, successfully rebutted? — Janus
Sorry, me no understand. — Lionino
So it's back to what I said here. Either we are most likely Boltzmann brains or we cannot trust our scientific knowledge. — Michael
ChatGPT 3.5
User
are there any physicists who believe we are boltzmann brains
ChatGPT
The concept of Boltzmann brains is a speculative idea in physics proposed by Ludwig Boltzmann and later expanded upon by physicists like Sean Carroll and others. It suggests that it's statistically more likely for a conscious observer, like a human brain, to spontaneously fluctuate into existence in a high-entropy state rather than to arise through the natural process of evolution. While some physicists entertain this idea as a thought experiment to explore the implications of cosmology and the second law of thermodynamics, it's not widely accepted as a serious hypothesis. Instead, it raises questions about the nature of reality and our understanding of the universe.
User
do any physists claim to be a boltzmann brain
ChatGPT
It's unlikely that any physicist would claim to be a Boltzmann brain in a literal sense. The concept of Boltzmann brains is primarily a thought experiment rather than a literal assertion about the nature of consciousness or existence. Physicists who discuss the idea typically use it to explore the implications of certain cosmological theories and the second law of thermodynamics, rather than as a statement about their own existence.
That's a false dichotomy, and things aren't nearly that black or white. — wonderer1
There are areas in which I can and do trust my scientific knowledge with my life (and the lives of other people) depending on it. There are other areas of scientific knowledge in which I can't trust my knowledge to nearly the same extent. — wonderer1
Consider this strengthened argument:
1. If we are not Boltzmann brains then our scientific theories are true
2. One of our scientific theories is that we are most likely Boltzmann brains
3. Therefore, if we are not Boltzmann brains then the scientific theory that we are most likely Boltzmann brains is true
Do you see the problem with (3)? — Michael
Which is why I asked the question: given that we have scientific evidence that entails that we are most likely Boltzmann brains, what justifies our claim that we are not most likely Boltzmann brains? — Michael
3 is a contradiction, hard to disagree with that. My point was more that you seemed to agree with Sean Caroll, because his argument was the opposite of the premise that you refuted by probability in the original argument. Sean's point is about justification. — Lionino
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