The illusive Space-Time: How large is the Universe?
Spacetime fabric (Image Courtesy Wikipedia)
No matter how hard I think, I can’t even come close to visualizing space time. And I am sure not even Einstein could , though he was the one who came up with the counter-intuitive and bold concept of time dilation. While the maths is absolutely spot-on and it has lived up almost a century now, describing the world at an macro scale scale (yes, the quantum world has got a different set of maths), I am sure it would take us ages to be able to engulf it (but if Darwin was correct, we would ultimately “evolve” to be able to visualize it, provided we survive long enough).
Anyways, to cut it down, I somewhere read that the diameter of the observable universe is about 97 billion light years, i.e. it is about 48.5 billion light years radially. Â How can that be? If nothing can travel faster than light, and the age of the universe is about 13.7 billion years (that is when the big bang happened) how could there be anything visible beyond 13.7 billion light years? This question (and a 100s of others) pop-up every now and then to me. I am lazy enough to sit on them for quite some time until it starts disturbing me. And this one did! And it took just about 10 minutes to get the answer (or rather explanation). So the idea is that the space itself can expand. I knew space could bend, but now I know it can expand as well. Well, even if the space expanded at the speed of light, the radius of the universe should have been about 27.4 billion light years. But that is not the case. The answer to this is that space did not respect Albert Einstein and it decided to expand faster than the speed of light! Wow, isn’t that really cool? With this, even if someone says that the universe is a billion billion quadrillion light years in the diameter, you can’t question that, could you? I noticed that there is already the notion of *observable* universe. There are things beyond that, which we can’t see.
Could the mysterious and illusive dark matter, which is yet to be understood throw some light on it? To me space itself  is nothingness (though it can be filled with something), and how could nothingness expand? What if the dark matter (or something else) is such that it makes light travel ridiculously slow when it passes through it? Wouldn’t it make all our distance observations overestimated? Well I know, there are enough reasons for this not being true, else someone would have brought it up for sure. But the point is that it looks to me,  that in the last century or so we have created a complicated  aura around all this. It has to be simpler. It really has to be. Otherwise it is not true.
Cosmology has always attracted and eluded me since childhood. I just wish that during my lifetime, we witness a spectacular theory or discovery which takes us a step ahead. Wouldn’t it be cool if we discover the mysterious dark matter? Or the fact that things can travel faster than light? Or something more beautiful than E=Mc2
And then, there’s quantum mechanics. I wouldn’t talk about it in this post at all. Einstein wouldn’t have liked it 🙂
