In the past year, I have noticed some strange concepts being presented as valid or at worst plausible concepts. They seem crazy to me. Maybe the Publish or Perish syndrome is the motivation. Maybe some people with academic credentials are a few cards short of a full deck. Boltsmann Brains are described in New Scientist magazine (August 2007) and NY Times Science Section (Tuesday 15 January 2008). What are the chances that an every day object (rock, chair, et cetera) could suddenly appear out of thin air? Not zero. It is conceivable that a conscious being could arise, even if only for a microsecond.

Here’s the problem: Some well established cosmological models predict that trillions of years in the future, Boltsmann Brains could vastly outnumber ordinary observers like us.

It is hard for nature to make an entire universe. It is much easier to make fragments: A planet, you in a space suit, or a naked brain floating in space.The above quotes merely give a hint of the full articles. At least the NY Times article mentions that these are consequences of certain models, not accepted by many (if any) cosmologists.

I see no problem to be solved: Get rid of whatever assumptions lead to such absurdities and make some new models.


NY Times Science Section (Tuesday, 14 August 2007). If you accept a pretty reasonable assumption of Nick Bostrom (Oxford university), it is almost a mathematical certainty that we are living in some one else’s computer simulation. Bostrom mentions the Matrix, but points out that his view does not include your having a flesh & blood body somewhere.


Scientific American (December 2007) describes the Many Worlds interpretation of Quantum Theory. This is also described in various serious books on Quantum Theory (EG: Gribbin’s Schrodinger’s Kittens & the Search for Reality). None of the proponents of this theory discuss the matter & energy implications, which make the theory absurd. A new universe is required for each alternative outcome of every quantum event. This postulates the creation of at least billions of universes per second, with each spawning at least billions more per second when created. It is assumed that these universes cannot interact due to being 3D or 4D objects in 5D or higher dimensional hyper-spaces. Still the matter/energy requirements seem absurd, and creating billions or more universes per second without any interaction seems to require some explanation.If some crackpot proposed one of the above notions, he would be totally ignored instead of being published.

The proposers of the Boltzmann Brain notion seem to have no clue relating to the complexity of a conscious human brain. Even if given infinite time, there are constraints on the results of probabilistic events.

You can throw dice forever and never roll a total of 13. Similarly, analogous constraints prevent the spontaneous creation of a conscious brain due to chance occurrences over infinite time. This consideration also strongly negates the concept that in infinite time an exact copy of some current individual will occur in some future universe (this is a very questionable notion related to the Boltzmann Brain Theory).

Bostrom does not seem to recognize the vast difference between the SciFi concept of the Matrix and his notion. In the Matrix, a conscious brain is provided with sensory input providing a virtual reality. This is a formidable task, and might not ever be accomplished. Even if the technology is possible, it might be unfeasible due to the cost. At least the technology required by the Matrix need not provide a different virtual reality for each individual in the Matrix. It need not allow an individual to travel beyond his own local environment. Bostrom’s notion requires the creation of a conscious mind as well as requiring the simulation of an entire world in which he can travel and interact with a huge variety of other individuals. That task is orders of magnitude beyond the technology required for the Matrix.

BTW: The Matrix was very sloppy SciFi. The virtual reality and the actual reality were poorly separated. For example: The martial arts sequences had to be virtual, making the outcome have no effect on the actual reality; A pill swallowed in the virtual reality should not have an effect on the actual body in the reality of the Matrix environment.

The proposers of the Boltzmann Brain notion seem to have no clue relating to the complexity of a conscious human brain. Even if given infinite time, there are constraints on the results of probabilistic events.

Well, "complexity" appears only to lower the transitional probability, as far as I can tell, which doesn't matter.

You can throw dice forever and never roll a total of 13. Similarly, analogous constraints prevent the spontaneous creation of a conscious brain due to chance occurrences over infinite time.

This needs an argument. You'll never roll 13 as the sum of a pair of dice, even given infinite rolls, because that outcome has probability zero. You haven't argued that a Boltzmann brain has probability zero.

What constraints are you thinking of?

This consideration also strongly negates the concept that in infinite time an exact copy of some current individual will occur in some future universe (this is a very questionable notion related to the Boltzmann Brain Theory).

Well, you haven't actually given any consideration other than disbelief. While extremely unlikely, I don't see that it should be impossible, and any event X with non-zero probability P(X) is bound to happen given infinite retries:


\forall P(X) \in ]0,1] \quad. \quad
\lim_{n \rightarrow \infty} 1 - (1-P(X))^{n} = 1

I think you would have more succes attacking the idea that infinite time implies that infinite retries are possible, but I'd like to hear why you think the transitional probability of, say, a Boltzmann brain is exactly zero, i.e. impossible, instead of "merely" mindboggingly improbable.

Boltzmann brains are actually an old concept.

Maybe this discussion by Sean Carroll will be helpful:
http://cosmicvariance.com/2008/01/14/boltzmanns-universe/

You can throw dice forever and never roll a total of 13.

How many dice? :)

There are more than two atoms in the universe, you know...

If some crackpot proposed one of the above notions, he would be totally ignored instead of being published.
But crackpots come in two flavours - those with a wacky new (usually untestable) theory, and those that reject current science (relativity/QM/string theory......) merely on the grounds that it doesn't accord with their everyday experience of what they call "the real world". One sees this all the time on various science forums.

Surely you're not one of the latter?

This needs an argument. You'll never roll 13 as the sum of a pair of dice, even given infinite rolls, because that outcome has probability zero. You haven't argued that a Boltzmann brain has probability zero.
Dice rolls are a simple process subject to a easy analysis of the probabilities. The spontaneous creation of a conscious brain is a very complex process. Can those who claim that the probability is non zero provide an analysis to support this claim?

We have evidence of a long evolutionary process resulting in the development of conscious brains. With all of our current knowledge, can we calculate the probability of this occurring? We cannot begin to do the analysis, but can be certain that the probability is non zero but infinitesimally close to zero. The most we can say is that since it happened, the probability is not zero.

Until somebody provides even a vague hint that disembodied conscious brains exist, I consider it very reasonable to assign a zero probability to the spontaneous creation of such an object. The only relevant evidence we have is that a conscious brain is the result of billions of years of evolution, unless you are a theist and willing to accept the biblical account.

What is the probability of the satellite of some planet consisting of goat cheese? It is imaginable, but does it have a non zero probability of occurring? I certainly would not expect it to occur as the result of the evolution of a solar system. Could it occur spontaneously due to a quirk in the quantum vacuum? Why should I think so when I have good reason to believe that it cannot occur as the result of a some what understandable process?

Does anyone here really believe that any imaginable item can occur as the result of a spontaneous quirk in the quantum vacuum? We seem to have observable evidence of simple objects (various particles) spontaneously popping into existence. Cosmologists extrapolating backwards from evidence of an expanding universe conclude that it started spontaneously, perhaps popping out of a quantum vacuum. Note however that the initial universe was not as complex an object as a conscious brain.

What is the justification for believing that an object as complex as a functional reclining chair can spontaneously pop into existence? How about a working internal combustion engine or a suspension bridge? Is the probability of the spontaneous creation of such objects larger or smaller than the probability for a conscious brain?

Oddly enough, I suspect that claims about reclining chairs, internal combustion engines, and suspension bridges might be greeted with scorn, but some are willing to accept the possibility of a spontaneously created conscious brain. I say nonsense.

I did not think it was necessary, but in response to some posts, I have provided some cogent arguments (not proofs) in favor of my view.

Can any one provide some arguments in favor of the possibility of the spontaneous creation of a conscious brain?

Hi Dinosaur,

I'll try to address some of your points. Excuse the editing.

We have evidence of a long evolutionary process resulting in the development of conscious brains. With all of our current knowledge, can we calculate the probability of this occurring? We cannot begin to do the analysis, but can be certain that the probability is non zero but infinitesimally close to zero.

Certainly not. The probability is unknown and non-zero, but in no way can you conclude that it is "infinitesimally" close to zero. For instance, I'm of the conviction that the probability, in this universe, is almost certainly 1.

Does anyone here really believe that any imaginable item can occur as the result of a spontaneous quirk in the quantum vacuum? We seem to have observable evidence of simple objects (various particles) spontaneously popping into existence.
[...]
What is the justification for believing that an object as complex as a functional reclining chair can spontaneously pop into existence?

You've just given it. Let's assume the various particles can spontaneously pop into existence (with some very low probability) due to quantum fluctuations, local conservation law violations, whatever. Then what is the probability that an electron and a proton's constituent particles will pop into existence exactly so they form up to make a hydrogen atom? Extraordinarily lower. Possibly even so low that we will have to wait on the order of several universe ages for it to occur even once anywhere in the universe. But the crucial point is that it does not have zero probability, i.e. it is not impossible.

Extrapolate from there, and the reclining chair (or suspension bridge or disembodied brain) has a ridiculously low but non-zero probability of randomly popping into existence at any given moment. And then, the argument goes, given infinite time, it will happen (because the likelyhood of any possible fluctuation not happening in infinite time is zero.)

I did not think it was necessary, but in response to some posts, I have provided some cogent arguments (not proofs) in favor of my view.

To be honest, I don't think you've done anything other than repeat your disbelief. I agree with you that brains are extraordinarily complex objects, but I can only see how this should lower the probability of them spontaneously popping into existence as compared to simpler objects, not that it would render it impossible. For instance, I should think that suspension bridges were much more likely than disembodied brains ;)

Can any one provide some arguments in favor of the possibility of the spontaneous creation of a conscious brain?
I think that if you accept the possibility of simpler objects (a small fluctuation) occuring out of nothing, it follows quite easily that more complex objects (a large fluctuation), while (exponentially) much rarer, must also be possible.

Do you have any other arguments as to why it must be impossible?

BenTheMan: Thanx for the interesting link, which seems to provide some support for my view. After the remarks addressed to FunkStar, I have made some comments on that article.

QuarkHead: Thanks for suggesting that I do not have an open mind. Perhaps you intended it to be a compliment. I know some people who have minds so open that some of their brains fall out, allowing others to put trash into the empty places. Are you one of those types?

I do not happen to one who will not accept notions which seem counterintuitive to me. If I were, I would be one of those arguing against relativity & quantum theory.

FunkStar: First, let me mention a common fallacy relating to assigning probability to events which have already happened as suggested by the following from your post.Certainly not. The probability is unknown and non-zero, but in no way can you conclude that it is "infinitesimally" close to zero. For instance, I'm of the conviction that the probability, in this universe, is almost certainly 1.I play duplicate bridge. When dealt a given hand, it has happened and you might be inclined to assign a probability of one to its occurring. However, for any possible hand, the odds are over 635 billion to one against its being dealt. For any deal, the odds are about 5.3628 to one against it. Yet I see 24 to 52 such improbable occurrences every day that I play.

The more cogent question is: If I shuffle and deal again, what is the probability of getting the hand I was just dealt? It is surely not close to one. In terms of our current existence: If the solar system was restarted as of 5 billion years ago, what is the probability of the second result being exactly what we see today?

Prior to Quantum Theory, most believed in a deterministic universe and would not consider the question to be a probability problem. They would claim that it would happen again exactly the way it had to happen the first time.

Your assignment of a probability of one to our current existence is a claim that evolution is deterministic rather than due to probabilistic mutations culled by natural selection. I repeat: We have no idea of the probability of the outcome of a few billions years of evolution, but the currently observed result has a probability close to zero.

Now on the issue of Boltzmann brains, functional reclining chairs, et cetera popping into existence.

You folks have to be led through an analysis. Why not use some of your own analytical abilities? The following provides a bit more argument for my view.

The dice throw example was merely meant to show that a probabilistic process might have constraints, EG: The probability of rolling 13 with ordinary dice is zero. Dice throws are merely a simple example of such a process, subject to easy analysis. It suggests that more complex processes might have less obvious constraints. For example:I could write a program which generates random integer coefficients for polynomials with odd order greater than 50. For each polynomial, the program solves for a root. If you know only the results of the process, you might think that the probability of generating a transcendental number is non zero.The above is a purely numeric process with an unobvious constraint, which is what I hoped to suggest with my example of throwing dice with no chance of 13 as a result.

Now consider what is known about objects popping out of the quantum vacuum. As far as I know, there is no evidence that any objects other than elementary particles pop out of the vacuum. At least I have never heard of any evidence for a carbon or oxygen molecule popping out of the quantum vacuum. How do you get an object as complex as a reclining chair if only elementary particles are created?A reclining chair consists of well over 1024 elementary particles. Furthermore, you need them to pop out in a small volume of space in a small time interval.


Particles with opposite charges attract each other with a force about 1037 stronger than gravity, quickly forming electrically neutral atoms. Big Bang cosmology indicates that a mix of elementary particles form hydrogen & helium, with only trace amounts of more complex elements. An analysis of the geometry of a mix of 1024 elementary particles in close proximity might very well show that formation of hydrogen & helium use up well over 95% of the particles, preventing the formation of enough carbon, oxygen, & other elements required for your reclining chair or Boltzmann Brain.


The early universe seems to have been almost exclusively hydrogen & helium. If it was due to a huge amount of matter popping out of a quantum vacuum, it surely suggests constraints on the elements produced.It seems to me that there is good reason to believe that there are constraints on the complexity of the objects which can pop out of the quantum vacuum.

BenTheMan: The article provided at your link restores some respect for those who write about Boltzmann Brains. I thought they believed that such phenomena could actually occur, rather than viewing the concept as a reductio ad absurdum argument against certain aspects of modern cosmological theories. I wonder if it is due the science reporter not understanding what he was told or due to his desiring to make the story more entertaining.

As indicated above, it seem to me that there are constraints on what can possibly pop out of a quantum vacuum. If there are constraints, the reductio ad absurdum argument against some cosmological notions seems weak.

Current cosmology describes an early universe which has extreme order from an entropy point of view, but a simple organization compared to a conscious brain. To me, it seems possible for the initial universe to pop out of a quantum vacuum without implying the possibility of a Boltzmann brain popping out.

BTW: I am not an advocate of the concept of the initial universe popping out of the quantum vacuum, but am willing to consider the notion in the absence of something better. I was a fan of the Steady State (or Continuos Creation) cosmology and was disappointed when various observations made it untenable. Due to this bias, I was hoping for an oscillating universe cosmology being revived: Alternating Bangs & Crunches. The apparent speedup of the expansion seems to doom this neat concept.

The notion of extrapolating backwards to a singularity seems to me to be the weakest part of the Big Bang Cosmology. It is not clear to me that extrapolation beyond the time of an opaque universe is justified by observational evidence. The Cosmic Microwave Background seems to support extrapolation back to some time when the universe was a plasma soup with no atoms.

I wonder if it is due the science reporter not understanding what he was told or due to his desiring to make the story more entertaining.

In general, the state of science journalism is in a pretty terrible state. Even the guys who write in the New York Times, and whatnot. The problem is that they are not scientists, they often don't have science degrees, and the NEVER understand what they are talking about.

As indicated above, it seem to me that there are constraints on what can possibly pop out of a quantum vacuum.

What supplies the constraints? I can think of no such constraints! Like funkstar said, the probability of a concious observer spontaneously appearing may be small, but it cannot be zero. Otherwise the ad absurdium arguments wouldn't work :)

The attitude we take in theoretical physics is to write down a theory, and see if any ``established'' reasoning can disprove it. This ``established'' reasoning may or may not include common sense---quantum mechanics, at least, has shown us that we can never truly understand the quantum vacuum.

FunkStar: First, let me mention a common fallacy relating to assigning probability to events which have already happened as suggested by the following from your post.
[...]
I play duplicate bridge. When dealt a given hand, it has happened and you might be inclined to assign a probability of one to its occurring.

Ah, no, of course not. And I'm rather astonished that you ascribe me this viewpoint, specifically because I wrote that the probability was unknown. Besides, I was not considering that scenario...

However, for any possible hand, the odds are over 635 billion to one against its being dealt. For any deal, the odds are about 5.3628 to one against it. Yet I see 24 to 52 such improbable occurrences every day that I play.

The more cogent question is: If I shuffle and deal again, what is the probability of getting the hand I was just dealt? It is surely not close to one. In terms of our current existence: If the solar system was restarted as of 5 billion years ago, what is the probability of the second result being exactly what we see today?

No, that's entirely uninteresting, from my point of view. I think you've misunderstood what I was assigning probability to - I was considering the probability that intelligent life would arise in this universe (which I believe has probability nearly 1*), not that it would arise exactly here with the result being what we see around us. I'll happily assign that a ludicrously low probability...

*To avoid confusion: I am not claiming that the fact that there is intelligent life has any impact on this probability.

It suggests that more complex processes might have less obvious constraints. For example:I could write a program which generates random integer coefficients for polynomials with odd order greater than 50. For each polynomial, the program solves for a root. If you know only the results of the process, you might think that the probability of generating a transcendental number is non zero.
The above is a purely numeric process with an unobvious constraint, which is what I hoped to suggest with my example of throwing dice with no chance of 13 as a result.

I don't think anybody missed your point, to be honest. However, you haven't presented any such constraints for what can pop into existence. That you think that such constraints must be there based on previous experience is not proof. Using the more advanced example, you're inferring from a finite sequence of algebraic numbers that no trancendental numbers will occur in the infinite series, also without knowing the underlying process.

Now consider what is known about objects popping out of the quantum vacuum. As far as I know, there is no evidence that any objects other than elementary particles pop out of the vacuum. At least I have never heard of any evidence for a carbon or oxygen molecule popping out of the quantum vacuum.

As I wrote, I don't expect such occurences to be common. I've never heard of it happening either, and I don't expect ever to hear of it. Does that make it impossible? No, it doesn't.

How do you get an object as complex as a reclining chair if only elementary particles are created?

By combining the elemtary particles, of course. Even though such circumstances are much more unlikely than "merely" the individual particles, I can't see that impossibility should be implied by this.

A reclining chair consists of well over 1024 elementary particles. Furthermore, you need them to pop out in a small volume of space in a small time interval.

Particles with opposite charges attract each other with a force about 1037 stronger than gravity, quickly forming electrically neutral atoms. Big Bang cosmology indicates that a mix of elementary particles form hydrogen & helium, with only trace amounts of more complex elements. An analysis of the geometry of a mix of 1024 elementary particles in close proximity might very well show that formation of hydrogen & helium use up well over 95% of the particles, preventing the formation of enough carbon, oxygen, & other elements required for your reclining chair or Boltzmann Brain.

No, it doesn't. That is the overwhelminingly most likely result from such a "particle soup", I agree. However, that doesn't rule out the result that the particles will form up into heavier elements, molecules, etc. ultimately combining to form a reclining chair. This may be (and is) an insanely improbably outcome, but that doesn't make it impossible.

In any case, we don't even need to start with a particle soup. We can consider the reclining chair as popping out of the vacuum fully formed, as an extremely unlikely (but still possible) quantum fluctuation.

The early universe seems to have been almost exclusively hydrogen & helium. If it was due to a huge amount of matter popping out of a quantum vacuum, it surely suggests constraints on the elements produced.

Again, no it doesn't. By the same argument as (ironically) the Boltzmann brain scenario against us living in a huge fluctuation, it suggests that early universes (if 300,000 years post big bang can be considered early) will consist almost exclusively of hydrogen and helium, but it doesn't preclude recombination from forming heavier elements. Again, I don't care that it is extremely unlikely to happen, just whether or not it is possible.

Your argument from what has actually happened is analogous to the following argument: Because mixed colour hands are all that everyone you know has ever received in all their games of bridge, this suggests that getting a perfect hand (13 of the same suit) is impossible.

Heuristics are not proof.

It seems to me that there is good reason to believe that there are constraints on the complexity of the objects which can pop out of the quantum vacuum.

I don't agree (as you may have noticed.) To echo Ben: What should such constraints be?

FunkStar: You are obviously one of those people who are willing to believe that any imaginable event is possible.

Check the link in the post by BenTheMan. It shows that even those who write about Boltzmann Brains do not believe they can occur. The concept was conceived as a reductio ad absurdum argument against certain aspects of current cosmological theory.

If you assign a nonzero probability to a conscious brain or a functional reclining chair, how about the entire universe as it now exists popping out?

How about our solar system popping out in its current condition?

Do you draw any line at all on what could possibly pop out of the quantum vacuum?

BTW: Do have any knowledge of nuclear physics & the origin of the 92 elements? Note in particular that protons repel each other with a force 1037 times stronger than gravity.

A functional reclining chair or a conscious brain being formed spontaneously seems more like magic than physics. I wonder if you have a clue about how big 1024 is. This is actually less than the number of atoms in a reclining chair or a conscious brain. Consider atomic nuclei like carbon & oxygen which consist of 11 to 18 elementary particles.

In all of our observational experience, even nuclei as simple as carbon & oxygen came into existence via some process rather than appearing spontaneously. All of the nuclei existing today with more than about 12 particles were cooked in the interior of stars from sampler nuclei. The process required incredible heat (millions of degrees) & pressure (thousands of atmospheres). Does this not suggest a constraint on spontaneous generation of complex objects like reclining chairs? To me, it suggests that there might be a constraint preventing the spontaneous creation of a nuclei as complex as iron (about 110 nuclear particles) in the absence of extreme heat & pressure.In the absence of observational evidence of spontaneous creation of complex objects, I would like to at least know of a theory hinting at what could overcome the repulsion between protons before believing in the spontaneous creation of complex objects.

Out of curiousity: do you believe in cold fusion?

FunkStar: You are obviously one of those people who are willing to believe that any imaginable event is possible.

No. Many imaginable events are impossible.

Check the link in the post by BenTheMan. It shows that even those who write about Boltzmann Brains do not believe they can occur. The concept was conceived as a reductio ad absurdum argument against certain aspects of current cosmological theory.

I wonder if you've understood the argument correctly. As far as I can tell, the argument assumes that Boltzmann Brains are possible, and even that a fluctuation the size of the observable universe (!) is possible. BenTheMan's post supports this.

If you assign a nonzero probability to a conscious brain or a functional reclining chair, how about the entire universe as it now exists popping out?

Well, much less likely than the reclining chairs, of course. I find it hard to assign it zero probability, though.

How about our solar system popping out in its current condition?

More likely than a fully formed universe, but still incredibly small.

Do you draw any line at all on what could possibly pop out of the quantum vacuum?

Well, impossible things, naturally. However, I have difficulties conceiving of the constraints. Of course, that's not really my problem, is it? It's yours.

BTW: Do have any knowledge of nuclear physics & the origin of the 92 elements?

Yes, I do. I'm not an expert, but I know enough.

Note in particular that protons repel each other with a force 1037 times stronger than gravity.

A functional reclining chair or a conscious brain being formed spontaneously seems more like magic than physics. I wonder if you have a clue about how big 1024 is. This is actually less than the number of atoms in a reclining chair or a conscious brain. Consider atomic nuclei like carbon & oxygen which consist of 11 to 18 elementary particles.

In all of our observational experience, even nuclei as simple as carbon & oxygen came into existence via some process rather than appearing spontaneously. All of the nuclei existing today with more than about 12 particles were cooked in the interior of stars from sampler nuclei. The process required incredible heat (millions of degrees) & pressure (thousands of atmospheres). Does this not suggest a constraint on spontaneous generation of complex objects like reclining chairs? To me, it suggests that there might be a constraint preventing the spontaneous creation of a nuclei as complex as iron (about 110 nuclear particles) in the absence of extreme heat & pressure.

Again, you are inferring from your knowlegde of how the universe has evolved, that a fluctuation away from the equilibrium cannot produce some of the results. That's a big assumption.

I wonder if you know statistical mechanics? Even though it's extremely unlikely, certain events which appear impossible from experience (such as all the air in your room spontaneously compressing to an extremely small volume in the center of the room, as dense and hot as a star) in fact have non-zero probability.

In the absence of observational evidence of spontaneous creation of complex objects, I would like to at least know of a theory hinting at what could overcome the repulsion between protons before believing in the spontaneous creation of complex objects.

Well, assuming that particles such as protons can spontaneously appear (probably rather rare in itself), then you can infer that they have some momentum, which itself can vary. Then it can also happen that some protons appear with just the right relative momentum to overcome electric repulsion.

Or, conceptually easier, they can simply appear in such close proximity that the strong nuclear force just dominates to form a nucleus.

Out of curiousity: do you believe in cold fusion?
No, of course not - please don't insult me merely because I don't agree with your argument.

FunkStar: You seem to read a bit, pick up a notion, and then think you understand it.I wonder if you know statistical mechanics? Even though it's extremely unlikely, certain events which appear impossible from experience (such as all the air in your room spontaneously compressing to an extremely small volume in the center of the room, as dense and hot as a star) in fact have non-zero probability.Apparently I understand Statistical Mechanics better than you do. I wonder if you know much more than the term itself.

You seem to be unaware that statistical mechanics does not allow for violations of the conservation laws relating to momentum & mass/energy. The scenario you mentioned above would undoubtedly violate one or more of these laws.

Your example requires temperatures in the millions of degrees (The surface temperature of the Sun is about 6000 degrees and the interior where the thermonuclear reactions take place is over a million degrees. Since temperature is actually a measure of particle velocity or kinetic energy, the air in my room could not get that hot without violating either momentum conservation or energy conservation or both.

If you learn a bit about statistical mechanics, you will not embarrass yourself in the future by making silly statements relating to the subject.

Your following view is interestingHowever, I have difficulties conceiving of the constraints. Of course, that's not really my problem, is it? It's yours.Of course you have difficulty conceiving of the constraints. You might be smart enough to consider them, but you have taken a position on this issue and now will stick to it without considering any other possibilities. Analyzing the possibility of constraints might shake your faith in your views.

Your attitude reminds me of the various fundamentalists arguing about creation & ID. Especially with respect to ID, they pretend to advocate logical arguments, but cease being logical when fallacies and/or certain awkward consequences of their logic are raised. Like the religious fundamentalists, you have faith based views on this and probably on other topics, while claiming to be an open minded scientist type.

Dinosaur:

So that would be a "No, I can't give any actual constraints." then?

Then I propose we close the subject. You obviously made up your made before you even started the topic, and in retrospect seem to have only been looking for affirmation, not debate. Coupled with your misplaced (and frankly unbecoming) hostility, there is little understanding to be gained by continuing.

FunkStar: I thought I gave some cogent arguements on the nature of possible constraints.So that would be a "No, I can't give any actual constraints." then?Perhaps you do not understand the nature of the possible constraints I described.

Sorry to be hostile. In some early posts, you suggested that I was narrow minded. Then in one of your recent posts you implied that you knew a lot about statistical mechanics and asked if I was familiar with the subject. You followed that question by a silly assertion indicating ignorance of statistical mechanics on your part. How could I resist a disparaging remark under those circumstances?

BTW: It is a nice ploy to suggest closing the debate tather than admitting your error or trying to defend the assertion about air in a room acquiring stellar temperatures.

FunkStar: I thought I gave some cogent arguements on the nature of possible constraints.

Perhaps you do not understand the nature of the possible constraints I described.

I think I do, I'm just not certain that they're relevant. The Boltzmann brain argument, as I understand it, goes something like as follows:

We're not living in an extremely large (and correspondingly rare) low-entropy fluctuation away from max-entropy equilibrium, because smaller fluctuations with essentially the same "result" (being intelligent observers), are correspondingly more likely. One such more likely fluctuation is the Boltzmann brain, which is exceedingly more likely than something on the order of the observable universe. Since we are not Boltzmann brains (and assuming that we can actually trust our senses) an entropic gradient for the universe is by far the more likely configuration.

It seems to me from this thread that you are claiming two things.

1. Nothing of any discernible complexity can arise out of nothing.
2. Fluctuations cannot produce anything as complex as Boltzmann brains.

Your argument for both points seems to be that our best explanations for the complexity and evolution of the universe (and of life, here) is not that it spontaneously happened as a fluctuation (to which I, of course, agree.) My counterargument is that this doesn't have an immediate impact on whether it could happen.

Sorry to be hostile. In some early posts, you suggested that I was narrow minded. Then in one of your recent posts you implied that you knew a lot about statistical mechanics and asked if I was familiar with the subject. You followed that question by a silly assertion indicating ignorance of statistical mechanics on your part. How could I resist a disparaging remark under those circumstances?

Point taken. In retrospect, some of my comments seem overbearing and snide.

BTW: It is a nice ploy to suggest closing the debate tather than admitting your error or trying to defend the assertion about air in a room acquiring stellar temperatures.
Fine, I'll concede the point about temperature. As it happens, I don't know that much about statistical physics, but I do know that the "air in a room" example is pretty standard fare. You seem to know your stuff, so I was assuming it would be familiar if you knew about it. I brought it up to counter point 2., above, in that a low-entropy configuration can happen as a fluctuation away from equilibrium - albeit very rarely.

In any case, what do you think about my suggestion that if elementary particles can appear out of the vacuum, then composite particles can too, by elementary particles appearing in the necessary configurations? It appears to me to be a pretty straightforward implication...

You seem to be unaware that statistical mechanics does not allow for violations of the conservation laws relating to momentum & mass/energy. The scenario you mentioned above would undoubtedly violate one or more of these laws.

Your example requires temperatures in the millions of degrees (The surface temperature of the Sun is about 6000 degrees and the interior where the thermonuclear reactions take place is over a million degrees. Since temperature is actually a measure of particle velocity or kinetic energy, the air in my room could not get that hot without violating either momentum conservation or energy conservation or both.

If you learn a bit about statistical mechanics, you will not embarrass yourself in the future by making silly statements relating to the subject. Actually, the example given by Funkstar is a very common example given in many statistical mechanics books and lecture notes.

The second law of thermodynamics is not a hard and fast rule in the sense that entropy may never, ever, decrease, if only for a moment. Statistical fluctuations which alter large physical systems' entropy by a measurable amount are hugely suppressed because in a room willed with 10^30 particles, the number of possible arrangements which leads to a set 'average' macroscopic system is vast compared to more likely setups like a small volume with high pressure and temperature. Of course such a setup is not 'stable' either, it would only happen for a microsecond (since the gas molecules move at huge speeds, even at STP), but it's none the less possible.

You're essentially saying it's impossible for the gas molecules to 'get out of each others way' in just such a way to allow them all to move into a small volume. This is clearly false.

Let's try something simple. Suppose I have two (or some a small number) particles bouncing around a box. Usually they are seperated by a distance of order the size of the box. However, every now and again they get really close to one another, even colliding. At that moment the 'box' which can enclose them is very small, much smaller than the contain they inhabit. They thus occupy a smaller volume. Nothing magic has occured, they just obey simple laws of motion.

If you have Linux distro, there's a game available which involves just such a premise. You have to fit n balls (n=2 to start, increasing with each level) into a set percentable of the box (~25% or so). You cannot alter the motion of the balls other than producing new walls for your box. Anyone familiar with the game (I think it's called 'Bounce') will be aware that if you time it right, you can fit all n balls into a very small space in one go. Obviously the amount of time you have to wait increases with n and the time interval you have available to you to make the new box decreases with n, but the times are non-infinite and non-zero (respectively) for all n.

AlphaNumeric: You misunderstand what I said in a previous post. I did not say the followingYou're essentially saying it's impossible for the gas molecules to 'get out of each others way' in just such a way to allow them all to move into a small volume . . . . . .I am quite familiar with the usual claim about all the molecules in a room collecting into a small volume.

The point I was trying to make is that the probabilistic laws of statistical mechanics do not allow violations of various conservation laws, thus putting restrictions or constraints on the possible configuarations of gas molecules in a room.

Momentum and/or mass/energy conservation laws would be violated if all the gas molecules in a typical room collected into a small volume and that volume had a temperature of thousands of degrees (stellar atmospheric temperature) or millions of degrees (stellar interior temperature).

My memory of the typcal example is the following (no mention of moving the container).A bottle of perfume is opened in a room full or ordinary air or a container of compressed gas is opened in an evacuated room.


After some time the perfume has mixed thoroughly with the air in the room or the gas has expanded to fill the room to an even density & pressure.


It is then stated that there is a small probability that all of the perfume or all of the gas will return to the orginal container. My memory of the above bit of statistical mechanics does not include a memory of the container being moved after being opened.

Until the discussion in this thread, I never wondered about what could possibly happen if the container was moved say from one corner of the room to another after all the perfume or gas had mixed evenly throughout the room.

I now wonder if moving the container would result in its being impossible for all of the perfume or gas to all return to the container. I suspect that this might violate momentum conservation.

BTW: Even if the container were moved, I am sure that some percentage (say 25-50%) of the perfume or gas could return to the container, which would be very counterintuitive as well as being highly improbable but not impossible.

I wish somebody I trusted to be an expert on this issue would post. I am curious about the effect of moving the container after the perfume or gas has been released.