The bedrock of science itself is causality: stable, predictable effects flow from discernable causes for some rational reason. But since science (and science fiction) is also about always questioning assumptions, it’s fair to ask if causality is in fact an appropriate bedrock for science. This goes beyond modern philosophical complications regarding causality due to discoveries in relativity and quantum mechanics. What if the laws of physics themselves – relativity, quantum mechanics, and even Clarke magic – change with time, and generated effects now or in the future are different from those at the dawn of our universe? This most fundamental of questions is examined in an excellent April “feature article” over on Physicsweb.
Changing the laws of physics or nature implies that so-called “physical constants” in the universe must change as well. Some physicists have believed (and some still do) that the Universal Gravitational Constant or G has changed with time, allowing gravity to be stonger or weaker with time. Most current theorizing on this subject today deals with a different physical constant called the fine structure constant or “alpha”. Change alpha and you change the strength not of gravity but of electromagnetism – how high a given amount of static electricity will make your hair rise, or how far from the nucleus of an atom an electron will orbit. Change alpha too much, your hair would barely rise off your shoulders as you scuffed your feet on a carpet. Also, electrons wouldn’t orbit atomic nuclei properly, falling instead into the central nucleus of an atom – something that would be a pretty devastating thing for life, far worse than having a bad hair day. The universe may not care if alpha is varying, but the life in the universe certainly has a stake in the question.
So, is alpha changing? Precise measurements on the light from distant quasars suggest that the value of the fine-structure constant may have changed over the history of the universe. If confirmed, the results will be of enormous significance for the foundations of physics. And whether we will all be here next week. Too bad we can’t ask Q.
I don’t think these results question causality; a change in what we think of now as a physical law would be yet another effect that has some underlying cause.
One interesting thing in the article – they indicate a change in alpha of about 1 part in 10^5 for a quasar 13 billion light-years in the past, but also state a number of measurements that indicate the rate of change of alpha in the past few billion years has been less than 1 part in 10^7 per billion years, or 1 part in 10^16 per year. They also claim all these are consistent, which might just be an error-bar effect, but if alpha was changing steadily with time, 1 part in 10^5 in 10^10 years is about 10 times higher than the recent experimental limits and the ones from the natural Oklo reactor and the other isotope measurements. So either the errors bars are still high on those numbers, or the rate of change was more than 10 times faster in the distant past than it has been for the last 4-5 billion years.
OK, gotta agree with you, this story per se doesn’t address causality. But on a gut level, it feels to me like it does. If you can’t depend on the constants of nature to be fixed, why should the rules of nature be fixed? Including the “effect follows cause” concept embedded in our current perception of time and reality? If gravity and EM can become stronger or weaker, then why not some weird things with time flow too?
you’re just following my old advice to be provocative and controversial, right? Anyway, to me a change in a “constant” of 1 part in 10^16 per year is pretty far from up-ending all our pre-conceived notions just yet. Maybe next week :)