Monday, January 26, 2009

YAST

No, I have not started using SUSE. Here, "YAST" stands for Yet Another Scientific Theory :)
Remember my old post regarding LHC? I haven't mentioned it before, but besides being sort of a nerd, I'm also into physics, mainly astronomy and particle physics.

A few days earlier I went to an activity organized at my school at which a university professor presented the accelerator. After the main event, me and two fellow students discussed with him various theories. One of his claims was that the Universe isn't expanding at an accelerated rate and that it might in the distant future stop altogether and start contracting, ultimately undergoing a 'Big Crunch'. After that it would explode and thus our Universe would be cyclical in nature. Of course, I was aware of this theory for a long time and even considered it the most likely one to be true at some point in the past. However, I recently read Stephen Hawking's book, "A Brief History of Time" (published in '88 I believe). In it, professor Hawking was against this cyclical nature of the universe, instead he opted for a Universe that was expanding at an accelerated rate. I'm not going to talk about this hypothesis, only about the 'Big Crunch' scenario version.

The way I see it, even IF the Universe would have enough dark matter to stop the expansion and gradually contract all the way back to a singularity it wouldn't be able to explode again with a Big Bang. This is because of the Second Law of Thermodynamics which states that the entropy of a system (and in our case the whole Universe) increases. If this is the case, then at each consequently Big-Bang the entropy is higher and higher. Finally there would be a state in which the entropy would be high enough not to cause a Big Crunch, all the matter in the Universe will be uniformly distributed, thus not allowing for galaxies, planets and life-forms to exist.

If the Universe doesn't undergo these cycles then it means that it must have a cause. Such a cause may be the "colliding Brane" theory, but it seems scientist aren't quite preoccupied with what happened before or what caused the Big Bang. In case you attribute it to quantum mechanics, then what are the conditions for a Big-Bang to occur? A completely-empty region of space it might seem. If there was mater inside the Universe at the moment of the Big-Bang then it might have had a strong impact on the Universe we see today, or the Big-Bang somehow annihilated everything, but if that's the case then another Big-Bang might just happen tomorrow, which seems pretty unlikely. Not to mention that we have to account for the massive amount of energy that's being thrown in, or if you want, you could say that in this model, a Big-Bang doesn't annihilate matter (energy) it simply absorbs it and then goes of. However, this again seems to contradict the 2nd law previously mentioned.

So, it would seem that in order for a Big-Bang to occur, you need a region in space (to be honest I don't know if you can call that space) that has no matter in it. But then, where would the energy come from? In quantum mechanics it is possible for matter to appear out of nowhere, but only on the form of a virtual particle-antiparticle pair. This is at the basis of the Hawking Radiation theory, I'm not going to go through that, my question is how is it possible for such a large amount of matter to be spontaneously created solely on quantum theory. And where all of the antimatter went? Is it because of the broken P symmetry?

So many questions to answer so few answers... it seems that for now at least, all we can do is guess, measure, and do the math, but at the end of the day, we still have to guess which result is correct.

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