Monday, November 26, 2007

Forget Global Warming: We Just Killed the Universe

There is a paper that has been posted on arXiv that has been causing quite a stir lately. It has even made it to the normal internet news services. Dr. Lawrence M. Krauss and Dr. James Dent, from Case Western Reserve University and Vanderbilt University respectively, have made the claim that by our observing dark energy we are affecting the life of the universe. Some news articles state it as "shortening" the life of the universe.

I tried to read through the article, but I'm not a particle physicist, nor a quantum mechanic, nor a cosmologist, but I'll give a crack at explaining it. So the idea is that in the early universe space was just as likely to decay into an unstable or metastable state that does not allow for matter, as we know it, to form or even for space as we know it to exist. But at some point the exponential expansion of the universe overcame the decay rate which is determined by a power law. Thus the universe began to grow faster than space will randomly decay, allowing for normal matter to form and for us to exist. But here comes the catch. If we observe the universe in some primordial state (i.e. observe dark energy) then the "quantum clock" of the universe gets reset and the universe reverts back to a state where the exponential growth and power law decay were roughly equal. Thus the universe reverts to a state where it is just as likely to decay as it is to expand. It follows that by our observing the universe in its most fundamental form we could conceivably cause it to decay into a state that does not allow for matter.

The problems with this are: What constitutes an observation? Do we have to observe the universe or does there have to be some interaction? in which case the observations are taking place all the time and our additional observing of the universe will not affect it any. From this point of reasoning we should assume that the universe is fairly stable (at least stable enough for us to be here, I think that is a very safe assumption) so I don't think there is anything that we can do that will significantly change the universe. The paper also mentions that it is difficult to make these assertions because they are based on quantum mechanics which doesn't really fit perfectly with gravity (GR) and when GR is taken into consideration things get sticky. Basically the only thing this idea can do is discount some versions of string theory and other unification theories.

So I hope that was a good interpretation of the paper. Let me know what you make of this paper.


  1. With this shocking news, there is only one man who can save us. That's right, the man who single-handedly did as much to fight global warming in 6 years as the lifetime work of a group of the world's most respected climate scientists. Only Al Gore can save us now.

    With any luck, he can make a movie about our universe-killing ways and then we can give him a Nobel prize in physics for his work. I just hope it's not too late.

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  3. On a more serious note, do we really think that we are the first intelligent life in the entire universe to observe dark energy? I have to believe that our continued existence indicates that observing dark energy will not destroy the universe.

    And by the way, aren't there some causality problems with someone being able to destroy the universe that gave them birth? It's like going back in time and shooting your grandfather, except in this case you're shooting everyone's grandfathers from 14 billion light years away.

  4. I did (and do) have a lot (A LOT) of doubts as to the possible interpretations of this theory. At first glance the theory doesn't seem that bad, it is based on known quantum effects, the problem is again the inability to incorporate GR among other things.

    Also if our universe as we know it has come into existence, then it is obvious that the early universe was stable enough for it to come into existence. Thus even if we revert to an earlier time in the history of the universe, then why should we assume that it will decay into a metastable or unstable state as opposed to further decaying into its current state. If anything we are helping the universe expand by observing it and interacting with it.

    Also as I pointed out in my post, What constitutes an observation? Does it have to be intelligent life or just some interaction with the rest of the universe? If that is the case then the "destructive observations" are happening all the time.

  5. "The problems with this are: What constitutes an observation?"

    Yeah, The philosophical interpretations of quantum mechanics are something to be careful of.

    *Especially* because we know quantum mechanics is just a low-energy approximation of some grander theory, so philosophies may not generalize in the grander theory.

    Oh Nick, I was going to make the movie about Saving the Universe to collect a Nobel Prize. I guess Al Gore will just beat me to it. :(

  6. Joe, I hate to burst your bubble, but you just aren't as qualified as Al Gore. You may have spent years working on the "science" needed to understand the problem, but Al Gore was Vice President for 8 years, in which time he clearly showed that he understands pretty much everything. And he "lost" the 2000 election to George Bush, which clearly adds to his qualifications since nobocy currently likes Bush. And to top it all off, he has some really big computer moniters in his office.

    Sorry Joe. At best, you might one day be like the Intergovernmental Panel on Climate Change. They are a collection of the best scientists in the world and have devoted their careers to studying climate change and still they are only worthy to share a Nobel Prize with someone as amazing as Albert Arnold Gore, Jr.

  7. Yes, I may only amount to a scientific panel.

    On a serious note, Gore didn't win the prize for being the one who did the science, he got the prize for bringing it to the attention of the public and world leaders who can back a solution.

    We can debate whether anything would be done about global warming if it wasn't "popularized" and made a major goal of much of the public and world leaders.

    This is why he won the prize. But I admit, he hasn't contributed to the science in any way.

  8. Well, not only that, but no one here has nearly as cool a middle name as "Arnold".

    Anyways, as far as what this post was originally about, I also think one of the fundamental questions is "what constitutes an observation?" In this case, I think it might be the thing that could actually save that theory. Yes, I still think it seems a little bird-brained, but the point is I don't think a system can collapse its own wave function. Schrodinger's cat couldn't collapse its own wave function by observing itself to be alive or dead. (Fortunately, in present company the concept of "observing itself dead" is perfectly admissible.) Now, if you're going to make an observation of the universe, such observations could not be by within the universe, namely by people (at least in the standard theory). So I think we're safe for now. The question as to whether we really constitute a part of the universe or whether there is anything outside of this universe to facilitate what might constitute an "observation," I personally think to be "not entirely" and "yes" respectively, but such questions probably belong more to the realm of theology or possibly philosophy than physics.

    However, the point is it doesn't seem that an observation from within the universe could really collapse it's wave function (think internal forces in Phscs 121). So, Joe, observe all you want. You can find dark energy, get your Nobel Prize, and I think we'll all still be around long enough to go to the celebration dinner.

  9. I think that is an excellent point Bill, that we could never have an internal observation that will result in a collapse of the wave function of the universe. But now the question becomes: Do individual parts of the universe have completely separate and distinct wave functions? or are all wave functions in the universe connected in some way? this might be bordering on philosophy, but having studied philosophy I would not want philosophers to (try) to answer that question. Though for any TOE it would have to be addressed, and depending on the answer it could determine whether or not we can cause space to collapse just by looking at it.


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