Sigh, I know what you're thinking. But given my inclination towards philosophy, atheism and, well, science obviously, this one was in the coming for years, at least. So, why now? Well, this post on Anne's blog, and the ensuing discussion below it.
Well, me being an atheist, you know what viewpoint to expect. I just want to be clear that I don't mean to insult anyone. If I do, I'm sorry. (Yeah, I'm writing this before writing the post. It, ehm, might get rough.) If I commit ad hominem or create men out of strings straw, do point it out though.
Enter, stage West
I have read, and debated, a lot about the concept of God in Western civilisation. It all comes down to one thing: The concept of God is what you should take on faith. It is your personal choice. A lot of people might agree with you, but that does not make it less personal, or truer. The email that inspired Anne's post comes from this worldview, but counters by saying that if God is to be taken on faith, so is Science. (Sorry, if I capitalise God but not Science, all my physics Physics books will spring to life and kill me.)
Anne and I begged to differ, of course. The scientific method is a tested and sensible way to develop models of the world. Models which "work", and by work I mean, they are predictive and have be tested in experiments which are repeatable. More can be found at Anne's post, but I wanted to repeat this because we'll need it below. Of course, there are subtleties, and loads of them, in Philosophy of Science. But, in the final analysis, it makes sense, is self-consistent, and works. By works, I mean, you can apply it to the real world. Here I'm quietly assuming a realist philosophy, but please, lets stay with that.
The concept of God (still in the west here) does not predict any observable phenomenon which does not have a valid scientific explanation. God does not lead to many testable, repeatable predictions, of course. (But see prayer.) Besides, the concept of a real true existent God (still in the West here) conflicts with what is the current state of knowledge in Cosmology.
Stage Centre: Science
How do I view Scientific knowledge as a whole? I think all Science has are models, but they lead to testable predictions which have been tested, and although issues like theory-ladenness, underdetermination, the demarcation problem, etc crop up, I think the fact that my hard drive is currently using GMR, and that our satellites have to apply GR corrections, leads me to be pretty confident that even some the most esoteric of today's theories, which have been built on a foundation of older ones, have a direct connection to reality. We may hypothesise about infinite "fields" in four dimensions, but face it, we can accurately predict cross-sections that we actually observe in our backyard accelerators. Science is not just self-consistent, it's held to reality at many, many points by strong connecting wires. You just cannot argue that I take Electric Fields on faith, because every testable prediction made by Maxwell's equations has been borne out.
See, there are theories, and there are the predictions the theories make. You are free to argue with me that Electric and Magnetic fields do not exist, but if you say that an electron placed in a cyclotron will not behave exactly the way my theory of "electromagnetic fields" says it will, I will punch you in the face. I have never observed a magnetic field, and I know I cannot. But if I assume that there exists a "electromagnetic field" which obeys certain "equations" I hypothesise, maybe out of thin air, and if I indicate every point my theory connects to experiment, and if every experiment has agreed with me, you just cannot say I'm taking my theory on faith. Please.
And it is here that we enter the Eastern religions. Specifically, those of India. Now I confess at the beginning that I do not know much about Indian religious philosophy. So there are probably many objections you can raise. I will skirt around the actual topics that I know nothing about, and hopefully some of the commenters might illuminate them.
I want to be very clear about my points at the start. A human being cannot live without food. People cannot defy the laws of gravity by pure thought. And finally, today's science is not rediscovering what Indian mystics had discovered thousands of years ago.
[Of course, when I say "Indian religion", I actually mean "Ancient Indian Philosophy". Thanks to Wanderer's comment on Anne's blog, I googled for ancient Indian views on Physics, and I have taken the help of three such links to write the following: One, Two and Three. Actually, just the first two. The third one is laughably silly.]
About not being able to live without food: sadly, the myriad such cases in India are very poorly documented, and the bastardised version of such "practices" in the west is very silly indeed. I cannot give any criticism to this except vouching for common sense. Same for levitation, which I guess is held indoors in secret clubs throughout the subcontinent, because I haven't seen anyone not claiming to be a magician do it yet, and neither has anyone I know. And here I vouch for more than just common sense: I vouch for Schwarzschild, the graviton, and the derivative of the Einstein-Hilbert action with respect to the metric.
A little note about the "Law of Karma": I cannot find a lucid enough explanation of it. Will someone in the comments please enlighten me?
And now for what people claim the ancients knew of Physics. Firstly, let us define two things: Knowledge, and Philosophy. (As I said earlier, I'll be a realist throughout the post.) I'll define Knowledge to be a human conceptual model which accurately represents the "real" world. (I knew philosophers will sneer as that statement and use it for coffee table jokes. For them, I'll define knowledge as the set of all Justified True Beliefs. I'm not a philosopher, mind you, so please refrain from insults and enlighten me in the comments.) Now, let us define Philosophy. It is the set of all human conceptual models. Knowledge is then a subset of Philosophy.
I ask the question: Are the Physics ideas in Ancient Indian texts knowledge or philosophy? Hmm... how we can test if something is knowledge?
One way would be to compare it to existing scientific ideas: here many of statements of Hindu philosophy seem to make sense. But I claim it's all a matter of interpretation. Let's see:
(From link one)
Other universes/wormholes. I saw within [the] rock [at the edge of the universe] the creation, sustenance and the dissolution of the universe... I saw innumerable creations in the very many rocks that I found on the hill. In some of these creation was just beginning, others were populated by humans, still others were far ahead in the passage of their times. [6.2.86]
It's easy to interpret this as the idea of a multiverse (I don't know where he got the wormhole from). But this isn't exactly scientific fact: Physicists are still debating how useful and observable the idea of a multiverse can be, and even though the idea of wormholes connecting different universes might explain some stuff, but no wormholes have yet been observed. Indeed, to travel between universes is almost impossible for human beings. You can object that we haven't yet attained the knowledge that the ancients had, but then I say, they should've given the recipe for inter-universe or wormhole travel too, if they actually knew it (a la Contact).
You can also object that this may just be ancient science fiction. But I object. The presence of science is required for science fiction. I'll come back to this below in the "third way".
A second way to test if something is knowledge is to look for how people arrived at it. The ancients arrived at their philosophy through pure thought, it is claimed (by Raj). Now, although it might be claimed that I'm adopting a modern western viewpoint which is unfit here, I think that knowledge can only be ascertained through experiment. Even the General Theory of Relativity was philosophy until Eddington's legendary experiment in 1919. (Not totally, though. See below.) I find no evidence that the ancients tested, or could test, their "preliminary ideas of gravity" or even those of wormholes.
Besides, there is no evidence that they actually had mathematical equations to accompany their concepts. In the absence of such equations, concepts cannot graduate to knowledge, simply because they have no predictive power. In the spirit of thinking big, Indians came up with their grand conceptions, but they were not based upon reality neither were they tested to see if they agreed with it. They were concepts, pure and simple. They may have been accurate, and I do not claim that there aren't passages where the conceptions sound disturbingly modern, and I do not claim that this isn't a matter of chance. What I claim is, without mathematics and without experimentation, these concepts are philosophical constructs. Philosophy too aims for knowledge. It results in the birth of science. Indian Philosophy is deep and beautiful. But there was no effort made for it to be "true", in our modern scientific sense.
The third way is to analyse a philosophical system and look for where the concepts behind the statements. In Indian Philosophy, we do not find any reference to basic Quantum Mechanical ideas, or to the constancy of the speed of light, or to the spacetime ideas of general relativity. We do not find any reference to knowledge of the nucleus which corresponds to modern ideas; we find references to "worlds within the atoms". In the light of this, I claim, that we should classify the references to "A single projectile charged with all the power in the Universe", or to the multiverse ideas mentioned earlier, as philosophical fantasy, not science fiction. One cannot get to the concept of wormholes without having basic notions of GR. One cannot have nuclear weapons without knowing about the nucleus and its constituents.
I said earlier that I might be accused of taking a Western view when analysing Eastern philosophy, which I did. But common sense tells us that knowledge has to be compared with experience. It has to work. Almost by definition, it has to "be" out there. Science is a very complex process. Theories are built on top of each other. One cannot get to the peak without climbing the mountain, or without your ancestors having formed theories of aerodynamics which allowed you to built flying machines which operated on those experimentally verified principles, and allowed you to get to the peak. Einstein's GR was an accepted theory in the scientific world even before 1919 because it was a generalisation of the experimentally verified SR, and it reduced accurately to Newton in the sensible limit.
Exit: stage East
In conclusion, even if the Ancients had aquired their knowledge differently than experiment, the lack of mathematical expression for it, and the impossibility of putting the cart before the horse in science leads me to be a little skeptical when anyone classifies their philosophy are knowledge.
What about the Idea of God, which we began with? Disregarding the actual prevalent theological ideas in Ancient India (God, Demons, Heaven, Hell and Earth), even if we think of the Sages as thinking God was one with the universe, of him being above, beyond and in time and space, one can only speak of the God as a philosophical construct. Thus, even God in Hindu philosophy is subjective. (That said, not all philosophical constructs are subjective. But there is much more scope for differing concepts in Philosophy then in Science.)
By the way, if you came so far (without scrolling down quickly too much), you deserve a thanks.