Archive for September, 2011

Faster-than-light (FTL) particles detected: implications for physics

Posted in Uncategorized on September 22, 2011 by quantummoxie

Physicists at CERN have reported what they believe to be evidence of neutrinos traveling faster than the speed of light.  Of course this is usually considered a big “no-no.”  So, on the one hand you have people saying that one of the fundamental pillars of physics is close to crumbling (NEWSFLASH!! Call the press!!).  On the other hand you have people saying the results are flawed because it’s just too ridiculous to be true (those people at CERN are idiots!).

Frankly, I hate the modern tendency to hype things to opposite extremes.  The truth of the matter is that a) the idea has been previously suggested and b) possibly even previously detected in Segré’s and Chamberlain’s famous antiproton experiment that garnered them the 1959 Nobel Prize (as pointed out by Cooper in 1982).  In addition, it seems to me that it is becoming clear to a lot of people that both time and gravity are emergent phenomena.  Since even special relativity is based on a metric that inherently assumes the existence of time, it would seem that relativity itself is emergent.  The “cosmic speed limit” (as Tom Moore calls the speed of light) is taken as one of two postulates from which relativity is derived (the other being that the laws of physics are the same in all inertial reference frames).  But that’s all it ever was in the beginning – a good guess.  It turned out that causality followed naturally from this assumption and human beings like causality because we can’t imagine how the world would work without it.  But maybe causality only applies to macroscopic objects.  It seems quite clear that fundamental particles simply do not follow the rules of classical physics (and relativity is a classical theory) so who’s to say they have to be causal?  In fact, there are lots of kluge’s in quantum field theory (QFT) that allow for all sorts of bizarre behavior (with all sorts of ad hoc arguments added to assuage our feelings about causality).

So does this all mean we toss relativity out the window entirely (not to mention the Standard Model and most of QFT)?  Well, no, not exactly.  Look, engineers (and by extension anyone who owns any GPS-based device) rely on relativity every day to make the GPS system work.  Likewise quantum electrodynamics (QED), which is inherently relativistic, is the single most accurate scientific theory known (it agrees with experiment to some insane number of decimal places).  So what it means is that we are merely pinning down the limitations on the theory.  All theories are really nothing more than models – they’re simply the most self-consistent way we have to describe the reality we see until we find something better.  For example, the discovery of relativity didn’t stop people from using Newtonian mechanics – again, engineers use it every day to make sure buildings stand up and cars drive properly.

So, in short, don’t believe the hype – either way.  It’s not the end of physics as we know it.  But it is wicked cool and very exciting because it means we’ve just discovered another “layer of the onion” we call the universe.

The nature of time: FQXi, Scandanavia, and the end of a hiatus

Posted in Uncategorized on September 7, 2011 by quantummoxie

I suppose it is appropriate that the post ending my nearly three-month-long hiatus is about the nature of time. I just recently returned from the absolutely fantastic FQXi conference Setting Time Aright that took place first onboard the National Geographic Explorer sailing the coasts of Norway and Sweden starting in Bergen, and then in Copenhagen.  It was eight days of intellectual bliss – interdisciplinary, cutting edge, and small enough that we could really all interact in some way. I met and/or hung out with some amazing people including Jaan Tallinn, Nick Pritzker, David Eagleman, Jesse Dylan, and Julian Barbour, among many others (see the conference website for a complete list). At some point soon the full conference will be available to watch on the Net. For now you’ll have to contend yourself with my pithy comments.

On the surface, it would seem that there was little agreement about the nature of time, i.e. what it is. Certainly the neuroscientists and psychologists have a very different take on it than the physicists. But I don’t think anyone would deny that what physics tells us time ‘is’ must be what time really is. The question is, then, does physics tell us specifically what time actually is?

Yes and no. Anyone who really studies physics will (or at least should) know that relativity has quite a bit to say about time (I recommend, by the way, the superb book Six Ideas That Shaped Physics, Unit R: The Laws of Physics Are Frame-Independent by Tom Moore for learning basic, non-tensor special relativity). In fact there are several kinds of time: coordinate time, proper time, and the spacetime interval (which is the kind of “time” measured by a photon).

That’s all very well and good for someone who doesn’t care about the fundamental nature of time and who only needs an operational definition. But physics didn’t get where it is today by remaining content with operational solutions to problems. Physics is, ideally, like a child that doesn’t stop asking why? So physics should ask where time comes from to begin with. Is it something that is fundamental to the universe or does it arise from something else? If it arises from something else we should seek to know how and why. One never knows the interesting doors this might open for further research (or even technology).

While there seemed to be a great deal of disagreement about the nature of time at this conference (e.g. Julian Barbour is convinced it doesn’t even exist), there very clearly was an underlying commonality to all of the views – even those of the psychologists and neuroscientists.

First let me say that one of the most striking things I found was that everyone’s work – absolutely every last one including the psychologists’ – involved either quantum mechanics or probability & statistics (including statistical mechanics and information theory, i.e. anything Edwin Jaynes would have written about – actually he wrote a bit about quantum stuff too). Ironically these are not the topics we emphasize in basic science and mathematics education (surprisingly few people have a good understanding of probability and statistics and most people are never even exposed to quantum mechanics!).

So given that commonality that seemed to cross disciplines, it is no surprise that pretty much everyone agreed that time has something to do with entropy. In fact many of the presenters and attendees probably think this is simply a trivial truth. So perhaps we should have been debating entropy, which is something that is still not entirely well understood as a concept. What is clear, however, is that it is some kind of statistical phenomenon. This is true for every single definition of entropy in every field (including instances in which the word is completely abused). Thus it would seem that there’s an underlying consensus – whether it is realized or not – that time must be some sort of statistical phenomenon.

This is actually quite remarkable. First, it points to the likelihood that time is not fundamental in the universe and so, in some sense, Julian Barbour is correct in that it doesn’t exist as a fundamental entity. In other words it would seem to be an emergent phenomenon. Second, if it is emergent, then due to the fact that it is at the heart of relativity, perhaps relativity is an emergent phenomenon as well (actually it is not difficult to argue this on a philosophical level). Following this line of reasoning would suggest that gravity would then have to be an emergent phenomenon (which actually makes some sense).

Now before everyone starts talking about these observations as being indicative of what was discussed at the conference, please know they represent my extrapolation from the commonalities I saw in all of the talks. Precisely how much of this any given attendee would agree with would likely vary greatly. Nevertheless, it is an intriguing line of reasoning to take and it certainly not unique (gravity has been proposed as being an emergent and/or thermodynamic phenomenon before).

What all of this means for your daily life is … well, nothing really. However, there were a number of talks that had some very interesting and useful insights into certain aspects of daily life. Keep an eye peeled for the conference videos (and a possible documentary). Nevertheless, they are fascinating and intriguing ideas to contemplate. Perhaps this sign from Bergen was a bit of a foreshadowing of the rest of the conference…