Tuesday, August 27, 2013

It's all relative

So the question came up after Sunday's run: has Einstein's theory of general relativity been proven? In other words, is it really still just a theory?

Unfortunately Brainiac still isn't answering his phone -- could he still be upset about that Wikipedia crack? -- and so in my own poor way I had to do the research myself. The conclusion may surprise you.

Einstein himself proposed three "tests" of his theory: 1) the perihelion procession of Mercury's orbit, 2) the deflection of light by the sun, and 3) the gravitational redshift of light. All three have by now been demonstrated beyond doubt, as well as many more newer tests. You can read all about it here.

But in fact we were asking the wrong question. Checking the Physics Forum (a very good U.S.-based forum backed by Scientific American magazine), I found this explanation by one of the boffins:

You don't seem to understand what a theory is. No explanation of natural phenomenon can ever progress beyond the status of "theory". The predictions of theories, if verified by experiments can be facts. Time dilates in a gravitational field: FACT. Time dilates in a gravitational field because mass bends a 4-dimensional space time continuum: THEORY. See the difference? The second statement can never be anything but a theory. Cause and effect is impossible to verify experimentally (because its a relationship). It can only be assumed based on repeated experiment, not proven. When people say "Relativity is just a theory, not a fact" or "Evolution is just a theory, not a fact", its painfully obvious they don't understand how science works. Theory is as good as it gets. You do not progress from theory to law. A law is just an assumed fact. The Law of Conservation of Mass: We assume that mass is conserved. We cannot prove it. But based on experience, it seems to be a reasonable ASSUMPTION. Theories, do not become laws. Laws are assumptions. Theories do not become facts. Facts are observations.

Law: Assumption
Fact: Observation
Theory: Explanation

None of the three can be "promoted" into being one of the others, they are seperate things altogether. Calling something a theory has nothing to do with its merit or accuracy. The idea of the lumiferous ether is still a theory, but is not given much credence. General Relativity is a theory, and is widely believed to be a close approximation to the truth. 

. . . so now we know.


  1. Ah, now a decent subject of debate we can all argue about! Actually my reference wasn't to general relativity, but to special relativity. Whilst I agree that the deliniation of laws, facts and theories is absolutely correct, general relativity still has one gaping area of doubt which is that, string/M theory notwithstanding, it is inconsistent with quantum mechanics at the sub atomic level. Special relativity on the other hand has been merged with and is completely consistent with quantum mechanics, in quantum electrodynamics. But I still find it really hard to get my head around special relativity which seems to abuse my notion of reality in a way that general relativity which at least offers an explanation in the form of curved space-time, does not.
    I reckon that the next ah-ha moment in humanity's appreciation of what reality constitutes will come not from the very mathematical-based theories which abound but can't be proved physically as matters stand, but from someone realising what special relativity actually implies, much in the way that Uncle Albert came along and turned physics away from the Galilean/Newtonian model towards a relativistic approach.
    Another beer?

  2. I am naturally a sceptic, and I want to see evidence and experimentation. Thus I have been carrying out extensive research on Mr Albert's Theory thingy. I can definitely confirm, that after years of experimentation, training relentlessly, sticking to a strict diet of almost exclusively Chang (what did you think the C was in E=MC2 silly!) and obtaining the almost perfect aerodynamic form that I have failed to arrive back at the beer truck before I left, I realise that this isn't definitive, but the speed of light is unlikely to be reached on this hash On On Gan Yao

  3. Don't see yourself short Gan Yao, you must be going fast because we can see the effects of redshift on you: you run, you drink beer, and you turn red.

  4. red shift - the expanding waistline, my navel is moving away from my backbone at an alarming rate. I postulate that originally I came from a single point, and in a split second everything about me came into being, lets call it the Big Buffoon!

    On On

  5. That would be a Brown Hole