1
$\begingroup$

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

$\endgroup$
1
  • $\begingroup$ Visible Universe? $\endgroup$
    – voix
    Dec 4, 2010 at 20:16

3 Answers 3

7
$\begingroup$

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.

$\endgroup$
1
  • 2
    $\begingroup$ Attention: $10^{80}$ refers to the observable universe. $\endgroup$
    – Sklivvz
    Dec 4, 2010 at 20:58
0
$\begingroup$

By composition The elementary particles of the Standard Model include

Six "flavors" of quarks: up, down, bottom, top, strange, and charm; Six types of leptons: electron, electron neutrino, muon, muon neutrino, tau, tau neutrino; Twelve gauge bosons (force carriers): the photon of electromagnetism, the three W and Z bosons of the weak force, and the eight gluons of the strong force; The Higgs boson.

Fermions Fermions are one of the two fundamental classes of particles, the other being bosons. Fermion particles are described by Fermi–Dirac statistics and have quantum numbers described by the Pauli exclusion principle. They include the quarks and leptons, as well as any composite particles consisting of an odd number of these, such as all baryons and many atoms and nuclei.

Quarks are the fundamental constituents of hadrons and interact via the strong interaction. Quarks are the only known carriers of fractional charge, but because they combine in groups of three (baryons) or in pairs of one quark and one antiquark (mesons), only integer charge is observed in nature.

Leptons do not interact via the strong interaction. Their respective antiparticles are the antileptons, which are identical, except that they carry the opposite electric charge and lepton number. The antiparticle of an electron is an antielectron, which is nearly always called a "positron" for historical reasons. There are six leptons in total; the three charged leptons are called "electron-like leptons", while the neutral leptons are called "neutrinos".

Bosons are one of the two fundamental classes of particles, the other being fermions. Bosons are characterized by Bose–Einstein statistics and all have integer spins. Bosons may be either elementary, like photons and gluons, or composite, like mesons.

And there are many more which are hypothetical like graviton , chargino, photino, etc... And many more at least a hundred if you count most fundamental If you know protons and neutrinos are not fundamental paricles

$\endgroup$
-2
$\begingroup$

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 sand......you find things like electrons and protons which we detect as wave forms of electromagnetic energy.

Weird isn't it!

$\endgroup$
2
  • 5
    $\begingroup$ 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! $\endgroup$
    – hdhondt
    Jul 12, 2012 at 0:56
  • $\begingroup$ 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. $\endgroup$
    – Phil
    Jul 13, 2012 at 6:08

Not the answer you're looking for? Browse other questions tagged or ask your own question.