A man of principles

"By denying scientific principles, one may maintain any paradox."

Galileo Galilei, born 15 February 1564

Last week saw the passing of two important dates. If you happened to forget the first of them, you may have ended up in domestic trouble. The second you may not have been aware of. The first date, the obvious one, was Valentine’s Day. Dating back to the days of the Roman Empire this celebration has been completely taken over by commercial interests. These days Valentine’s Day seems more about the purchase of roses and boxes of chocolate that any true sentiment. The other date, actually the day after, is more obscure. The 15th of February was the birthday of Galileo Galilei, often considered the father of modern science. This year he would have been 449 years old, so you might think it would have been wise to wait until next year to celebrate. I disagree. Since 449 is a prime, I think dear old Galileo would have been more keen on this celebration than the boring 450.

            I wasn’t really planning on turning this into an admiration session for a long dead Italian chap that may, or may not as the case may be, have dropped some balls from the Leaning Tower of Pisa hundreds of years ago. But then a couple of things conspired to turn my attention in this direction. The first was a lecture I gave on the principles behind Einstein’s general theory of relativity, the one that uses wonky space and time to explain gravity. Key to this theory is something called the Equivalence Principle. This essentially goes back to Galilei’s apocryphal experiment, as it states that two falling bodies accelerate at the same rate (as long as you ignore air resistance). In my opinion, the most stunning demonstration of this fact was when Buzz Aldrin, the second man on the moon, dropped a feather and a hammer to show that they landed at the same time. I don’t know who suggested adding the hammer and feather to the moonlander’s payload, but the video of the event is just great. I particularly like Buzz’s comment (“How about that!”) when things worked out as they should. I wonder what he would have said if there had been a different outcome....

            The scientific method, of which Galilei was an early supporter, basically decides what is credible and what is not in the world of research. Ideas are only valid if they can be backed up by experiment. The experiments don’t have to easy, they may require a future civilization with an arbitrary advanced technology, but they have to be possible in principle. If a theory is not testable in this way, then it is not proper science. As an example, consider Peter Higgs’ boson. This little thing has long played a central role in particle physics (explaining why particles acquire mass). Yet it was only very recently, and after the astronomical expenditure involved with building and running the Large Hadron Collider that there was any tangible evidence for this idea.

            The other side of the coin, an example of an idea that may remain more philosophy than science, is the so-called Anthropic Principle. This provides an answer to the vexing question of why the Universe in so fine-tuned, and why we happen to live on a planet that is so perfectly suited for humans. The explanation draws on a notion that is popular in string theory; the Multiverse. The idea is that there are many (read: an infinite number of) parallel Universes. We live in this one simply because we can. Most alternative worlds would be too hostile for us. This is undoubtedly an elegant way to argue yourself out of a corner. But... and this is a major reservation... it is not science in the sense of Galilei unless you can somehow demonstrate the presence alternative worlds. I guess all it would take is a portal to a different Universe. Wouldn’t that be something? It would, but I suspect we will have to wait for that arbitrarily advanced technology.