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Total number of subatomic particles in the universe. Are they finite ? assuming any of GR or QM or even ST.

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Visible Universe? – voix Dec 4 '10 at 20:16
up vote 7 down vote accepted

It's possible to make an estimate of the amount of baryons in the observable universe. But it's more difficult to make an estimate of anything else. It gets particularly more difficult when you consider things like photons, because they can pop in and out of existance, i.e. the number of photons is not constant. Actually, that is true for all elementary particles, since they are considered as excitations of quantum fields in most modern physics theories. Thus, the number of particles is not constant. But the heavier the particle, the less likely it will pop in existance. And if it's too heavy, it'll decay in lighter, more stable particles. So maybe you'll have something a couple of orders bigger than the amount of baryons, but probably not much larger.

Then, there is dark matter, of which we don't really know much. So, I have no idea if an estimate has been attempted of the amount of dark matter particles. Any estimate will be highly dependent on the theory we have for these particles.

In his book The Emperor's New Mind, Penrose estimates the number of baryons in the observable universe to be of the order of $10^{80}$. This seems to confirm it.

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Attention: $10^{80}$ refers to the observable universe. – Sklivvz Dec 4 '10 at 20:58
Thanks, I corrected. – Raskolnikov Dec 4 '10 at 21:32

What are particles? I don't think they are sub-atomic, incredibly tiny billiard balls whizzing around. If so, then what is the substance of these particles?

My logic - and I could be wrong - is that what we refer to as particles are persistent standing waves in the ocean of electromagnetic radiation in which the entire universe bathes. These incredibly tiny eddies in the EM ocean, when aggregated in vast numbers and in a huge number of permutations and combinations making up the elements we are more familiar with, form the substance and the space of what we perceive and detect as matter, inertia, gravity, space and so on..

I read that there are about 10 to the power 80 particles in the universe. Seems like a manageable number except that it is far, far greater number than the grains of sand on every beach and in every desert on earth. And when you dig deep into the atomic structure of each of those grains of find things like electrons and protons which we detect as wave forms of electromagnetic energy.

Weird isn't it!

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Weird that the number of particles in the whole universe turns out to be greater than the number of grains of sand on one small planet! – hdhondt Jul 12 '12 at 0:56
Yup...weird is right. But the millions of "particles" that make up just one grain of sand gives lie to that number - 10 to the power 80. – Phil Jul 13 '12 at 6:08

protected by Qmechanic Oct 10 '13 at 9:37

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