Locklin on science

Is physics the same everywhere, at all times?

Posted in physics, physics anomalies by Scott Locklin on July 22, 2009

One of the fundamental assumptions of modern physics is that it works the same everywhere in the Universe. I always wondered why this should be so. I mean, it makes possible a lot of the calculations used in astronomy, but that just makes the assumption convenient -it doesn’t make it necessarily true. I occasionally amuse myself with the game of “what if it were not true.” As such, I’m always on the lookout for stuff which indicates maybe it isn’t true. Here I present two potential pieces of evidence that the assumption about homogeneity of physical law is not true.

The first one is the oldest one, for which there is the most evidence. It is the Pioneer anomaly. Pioneer was a pair of spacecraft that produced the first up close photos and telemetry from Jupiter and Saturn in the early 1970s. They’ve since left the solar system. They are the farthest man-made objects available for study, so people study them very carefully. In fact, they found a very small, but unexplainable anomaly in their motion. It corresponds to an acceleration which is 10^-10m/s^2 towards the sun. Various explanations have been fielded; some pedestrian, some far out -none are particularly satisfying. Pedestrian explanations: perhaps there is lots of dirt slowing them down; perhaps some large mass is out there influencing the things; perhaps the waste heat is large enough to provide this much acceleration. For non-pedestrian explanations, perhaps gravity works differently than we think. This would be a disaster for astronomers and cosmologists. Perhaps physics itself is different in different regions of space. Whatever it is, this effect has been pondered for half a decade now, and they haven’t been able to make it go away. I had the germs of a paper trying to tie this to the solar neutrino problem, but I guess I have more self respect than most cosmologists, so I never bothered publishing it.

The latest one is even more disturbing. It indicates that radioactive decay changes over time. In fact, the rate of beta decay of certain nucleotides seems to be strongly correlated with earth’s distance to the sun. Now, in my opinion, this is rather indicative of systematic error -perhaps detector efficiencies are correlated to something that comes from the sun, like heat. They’re postulating something more radical: that neutrino flux (which varies with distance to the sun by 1/R^2) might have an interaction with these isotopes, or even more radical, that the sun emits some previously unknown field that alters the local fine structure constant. The neutrino instance would be a big deal; lots of nuclear models would have to be revisited. A field that alters the fine structure constant would be cataclysmic. They’ve already looked for and not found the effect in the radioactive power plants of the Cassini probe, which to my mind indicated that the effect is likely systematic error. I’m also not encouraged by the fact that the original paper contains statistical measures which look suspiciously like they did their statistics incorrectly. If anyone came to me with 35 data points and claimed correlation with 4×10^-12 probability, I would laugh at them. I’m guessing they got their “formal probability” by cranking it through some Student-T formula, which is pretty much wrong for calculating correlation probabilities like that. In another case, they actually have the kidney to quote a 2^10-246 probability, which is simply absurd. I mean, that sort of number verges on quantum mechanical absurdity (as in, I think it violates the uncertainty principle, though I don’t feel like doing the math). I suspect such primitive statistical ideology may be common in physics; physicists never learn real statistics. Financial analysts are arguably a lot more careful with their statistics, and they’re certainly more sophisticated than most physicists are. None the less, the signals are obviously correlated even if the authors arguably didn’t do the calculation right, and it’s an interesting result.

4 Responses

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  1. Craig Bryant said, on July 23, 2009 at 3:01 pm

    Well, if the cosmologists are on the right track, the Universe is made up of mostly Dark Energy, a good portion of Dark Matter, and some other odds and ends of relatively little consequence. If we ever start understanding the nature of reality, I imagine more than one applecart is going to get turned over.

    • Scott Locklin said, on July 23, 2009 at 6:42 pm

      I’m all for turning that applecart over. Science is most interesting when we don’t understand stuff. That’s why I like this sort of thing.

  2. Thomas Barton said, on August 7, 2009 at 11:45 pm

    Just found your site through a link. I enjoyed the Pioneer anomaly discussion and turning over applecarts mindset. What do you think of Subir Sarkar’s apparent disdain for the cosmological constant, the entire dark energy mindset ? Could you expand your biographical information to include where you trained as a physicist and where you worked as an analyst. I am always a bit annoyed by the coyness of bloggers who will expand at length on one topic and then clam up when it comes to the particulars of their own professional biographies.

  3. Scott Locklin said, on August 8, 2009 at 12:00 am

    I had a roommate in college who informed me of his becoming a cosmologist. We both agreed it was a good scam, as he could pretty much publish whatever he wants without fear of anyone calling him on it.

    For the purposes of argument, you can assume I’m completely unqualified to comment on anything, but I will persist in doing so anyway. Think of me as your friendly neighborhood menial laborer who reads a book from time to time.

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