Galactic Interactions

(I know I’m not doing this any more, but I couldn’t resist.)

An article in New Scientist reports on musing by two reasonable and respected cosmologists— indeed, ones whom I’ve met myself— that our discovery of dark energy may have shortened the life of the Universe.

To which I can only say “foo”. And I say “foo” on two levels. Primarily, on the sensational way in which this is described by New Scientist. But secondarily, on the interpretations of quantum mechanics that respectable cosmologists are promoting.

First of all, for a bit of perspective. The actual research paper on which this article is based is available at arxiv.org, from which I will quote the end of the concluding paragraphs:

The second consideration is even more interesting. If observations of quantum mechanical systems reset their clocks, which has been observed for laboratory systems, then by measuring the existence dark energy in our own universe have we reset the quantum mechanical configuration of our own universe so that late time will never be relevant? Put another way, can internal observations of the state of a metastable universe affect its longevity?

They are asking the question…. And what do we get out of “New Scientist”? Cosmologists observing the Universe may have shortened the life of the Universe! Geez.

If this is not an article tailored to feed fuel to the anti-science types who are warning of the dangers of “meddling in that which we do not understand and were not meant to understand,” I do not know what was. Now we have a respectable science magazine and two respectable cosmologists on record as saying just looking at the sky could hasten the end of the Universe ZOMG!. And while my quote of the scientific paper above may seem to restore respectability to Krauss and get him off the hook, he does have this sentence quoted in the New Scientist article:

If so, as incredible as it may seem, our detection of dark energy may have reduced the life expectancy of our universe.

The very first thing to keep in mind is that we are taking about timescales of 14 billion years. The Universe may die in 14 billion years instead of 140 billion years because we were so bold as to look at it, if you take the results of this too seriously. So there’s no need to worry about the effects this will have on the Christmas shopping season. (Well, unless the article itself raises worries.)

But there are other things to think about before we march to the offices and homes (including mine) of the two teams of astronomers who discovered Dark Energy, and burn them to the ground. Consider this. There are 100 billion stars in our galaxy. There are 100 billion galaxies similar to ours within our observable Universe. We know that planets are ubiquitous in our neighborhood of the galaxy. I will not make any estimation as to whether or not there are other life-bearing, or, more to the point, intelligent life-bearing planets in our region of the Galaxy. But do you really believe that nowhere in this observable Universe there is nobody else out there looking at the skies? I find that simply implausible.

More to the point though… this whole thing is reading too much into quantum mechanics. This is writing in a science magazine (New Scientist) interesting speculation that better belongs in science fiction (cf: Greg Bear’s interesting story “Schroedinger’s Plague”). I do have to admit that macroscopic consequences of Quantum Mechanics are something potentially very cool. But there are a lot of fuzz-heads out there who like to take things that scientists say about Quantum Mechanics and use it to claim that there some sort of scientific basis to their bogus mysticism (cf: How Much #%*! Can We Spew?). It sort of alarms me to see respected cosmologists quoted in a mainstream science magazine saying things about quantum mechanics that sound like Intelligent Design processed through the most stereotyped of post-modernist “reality is a social construction” deconstructionism.

There is real science behind this. There have been experiments showing the so-called Quantum Zeno Effect (also sometimes called “Quantum Non-Demolition”, unless I am mistaken) where a particle’s decay time can be delayed by observing it continuously. What happens here is that the particle’s “decay clock” is “reset” each time it is observed not to have decayed. I hereby poke Chad to talk more about this, because I suspect he knows a lot more about it than I do.

Is any of this real? In reality, we currently know so little about the true nature of Dark Energy, and so little about the conditions in the early Universe, that this is one of many thoughts that are out there in the theoretical mill being chewed on by people smarter than me. As we stumble our way towards some understanding of quantum gravity, we’re going to think a lot of “out there” things, many of which will turn out to have been completely on the wrong path, some of which may surprisingly turn out to be correct. There was a time not too long ago when some of the perfectly well understood consequences of quantum mechanics— e.g. the fact that nature is not deterministic, but stochastic, at its most basic level— seemed utterly nonsensical and impossible. Almost certainly something surprising will come out of quantum gravity. But we’re not there yet. So don’t become alarmed.

However, I may be proven wrong, but let me go on record as saying that I am deeply dubious that our Universe will turn out to behave as a quantum system in this manner. There is absolutely no doubt that quantum mechanics does have effects on macroscopic systems. Consider blackbody radiation, the spectrum of light we see from something like the Sun. The nature of that spectrum cannot be understood without quantum mechanics (and was one of the leading problems with late-19th-century Physics). However, the fact that you can’t explain the shape of the Sun’s spectrum without quantum mechanics does not imply that the Sun behaves as a quantum particle whose existence is in doubt when nobody happens to be looking at it. I suspect that the sorts of things we’re seeing here are the same kinds of “taking quantum mechanics too far out of its relam” mistakes.

Comments

  1. #1 Blake Stacey
    November 25, 2007

    To which I can only say “foo”. And I say “foo” on two levels. Primarily, on the sensational way in which this is described by New Scientist.

    You expected better?

    They think it’s their job. No, seriously: an editor told me so, in just about as many words.

  2. #2 Dustin
    November 26, 2007

    To the New Scientist I ask, “What constitutes an observation?”

    Dark matter and dark energy are so tied to the dynamics of galaxies, including our own, that even looking at the sky at any point would cause the kind of collapse they’re talking about, a la Schroedinger. Even if we aren’t aware of it, we can look up at the night sky and have our retinas bombarded by photons emitted by distant quasars and clusters of galaxies. Isn’t that an observation? Or do we have to be cognizant of the fact that we’re indirectly observing dark matter and dark energy whenever we look at anything? An affirmative answer to that question doesn’t make any sense, and if we answer no we have to ask what makes the interaction of a photon with our retinas more important than the interaction of dark matter with a galaxy. I don’t think it is any more important.

    I think it was Heisenberg who suggested that we’d ought to adopt the word “interaction” rather than “observation”. I’m sure that if we take that kind of view through to its conclusion, we arrive at something like the relational quantum mechanics described by Smolin, Rovelli, et al. The blogosphere seems to be populated by many-worlders and ensemble supporters, so I’ll probably be run off with torches and pitchforks for saying it, but there isn’t, as far as I know, any room at all for looking at the universe as having a wavefunction within the scope of relational quantum mechanics. I don’t think we have to wait for quantum gravity at all to say that it’s doubtful that the universe will display the kind of quantum behavior the New Scientist is suggesting it does.

  3. #3 Rupen Savoulian
    November 26, 2007

    Dear Rob

    This is another typically excellent post. I’m glad that you have (tenatively) returned to science blogging. Your ability to communicate is refreshing.

    Unfortunately, quantum mechanics is being bastardised by all sorts of mystic-merchants, creationists, Intelligent Designers (read ignoramuses) and other assorted galahs to promote a pseudo-spiritual, faith-based ideology.

    Keep blogging and Vanderbilt will realise that they have lost a talented scientist.

    Cheers from Sydney, Australia

  4. #4 GJJ
    November 28, 2007

    As a dedicated layman, I could only laugh when I heard this news. As you know the mechanics I’m best at are brakes on Mustangs – but the whole thing sounded to me like a movie reviewer was writing about this instead of a Scientist.
    Thanks for you comments.
    GJJ