Can matter be tranfered into dark matter and back?

[TheGeckomancer]

I specifically mean unaided. No technology. Could enough quarks be accumulated in one spot to have a physically visible chunk with light bouncing off.

[ajb]

Could enough quarks be accumulated in one spot to have a physically visible chunk with light bouncing off.

Quarks (together with gluons) usually form hadrons. None of these are large enough to see with the naked eye, or by any other direct means: they are just too small.

 

You could think about nuclei. However, the largest nuclei radius is of the order 15 fm. Visible light is 390 to 700 nm. You are not going to get a direct image of a nuclei using visible light.

 

 

 

Anyway, we do have evidence of quarks from deep inelastic scattering experiments.

[TheGeckomancer]

That was my point. So that makes particles outside of empirical realm. We cover that with indirect observation and thats okay, but to me particles aren't matter. It doesn't make sense to call it matter for several reasons. And that is one of them.

[ajb]

... but to me particles aren't matter. It doesn't make sense to call it matter for several reasons. And that is one of them.

It clearly depends on your definition.

 

In high energy physics one usually thinks of fundamental fermions as matter and then fundamental bosons as forces, for example.

Edited November 26, 2015 by ajb

[swansont]

A visible to the naked eye amount that I can grab with my fist. My point is i don't think you can stack them like sand on top of each other and ever have something you can SEE and touch. Correct me if I am wrong, but particles are strictly out of the empirical realm?

 

Then sure. Anything you grab is going to be a collection of quarks, conveniently bundled in groups of three, and wrapped in a cloud of electrons, with these wrapped bundles sticking together. You won't see the quarks themselves because they're too small, but you can see evidence of a group of three, as ajb notes, in a cloud chamber.

That was my point. So that makes particles outside of empirical realm. We cover that with indirect observation and thats okay, but to me particles aren't matter. It doesn't make sense to call it matter for several reasons. And that is one of them.

 

Are cells matter? You can't see them unaided with the naked eye, either? There are even examples of multicellular life you can't see unaided. They aren't real? That seems like an artificial and useless distinction.

[TheGeckomancer]

Enough cells in one place gives you something to look at and touch. Enough quarks in one place does not. I don't see that as artificial or useless. If no amount of a quantity makes it "real" then it's not matter.

Edited November 26, 2015 by TheGeckomancer

[Strange]

Enough cells in one place gives you something to look at and touch. Enough quarks in one place does not.

 

Those cells are made of quarks; nearly all their mass comes from the quarks (well, actually, the energy binding the quarks together). Quarks are clearly the main component of matter. </devilsadvocate>

[TheGeckomancer]

Component of matter. I am not trying to nitpick but even by that description it meets what I say. I am not calling quarks nothing. They are definitely the BUILDING blocks of matter. But not actually matter.

[Strange]

We seem to have got way off topic. Getting back to your original question, if it were possible for dark matter to decay into matter, or vice versa, then I assume such a process would release energy (and hence be detectable, in principal). But this would also imply it was a largely one-way process, which would mean that the amount of dark matter had increased or decreased over time (depending which direction is energetically favourable). As the amount of dark matter appears to be roughly constant (as far as I know) I guess this (and the absence of detectable radiation from dark matter) could be used to set an upper bound at which such a process could occur.

[TheGeckomancer]

If there is dark matter. (personally I favor the multiverse bleeding gravity hypothesis) I favor the idea that it would be an elementary particle. With no state to decay into.

[Strange]

If there is dark matter. (personally I favor the multiverse bleeding gravity hypothesis)

 

I don't think modifications to the way gravity works can explain all the observations. From what I have read, this requires a different modification to gravity for galaxies and galaxy clusters. Dark matter (as matter) is required to explain gravitational microlensing, it is required by models of large structure formation, and so on.

 

I favor the idea that it would be an elementary particle. With no state to decay into.

 

That seems to be the preferred model: that it is a particle, or class of particles, that do not interact. In some models, there are particle-antiparticle annihilations which should produce distinctive radiation.

http://www.sciencedaily.com/releases/2015/08/150820082508.htm

[TJ McCaustland]

Well......... wouldn't that technically be pretty much the same as turning Uranium 238 into Hydrogen and back? (which is impossible according to our current scientific knowledge)

[swansont]

Well......... wouldn't that technically be pretty much the same as turning Uranium 238 into Hydrogen and back? (which is impossible according to our current scientific knowledge)

 

You could, in principle, turn U-238 into hydrogen and back.

[TJ McCaustland]

 

You could, in principle, turn U-238 into hydrogen and back.

Yes, but the energy required would be ENORMOUS, Like 10^29 MJ enormous.

[swansont]

Yes, but the energy required would be ENORMOUS, Like 10^29 MJ enormous.

 

No, actually, it wouldn't. First of all, energy is conserved. The minimum energy required to take apart the nucleus is exactly the same as you get when you assemble it. From that standpoint it would take no extra energy at all. The minimum energy to take apart the nucleus is given by the binding energy. This being science (you should try it sometime) we can calculate the binding energy of U-238. It's about 1.8 GeV. (The difference between the mass of the constituent particles and the mass of the U-238, multiplied by c^2). Since some of the hydrogen would have to be deuterium and tritium, owing to all the extra neutrons, it would take even less energy than this to break the Uranium up into hydrogen.

 

That means you're off by at least 44 orders of magnitude . (there are 6.24 x 10^9 GeV/Joule) That's not typically considered "approximately correct"

[TJ McCaustland]

 

No, actually, it wouldn't. First of all, energy is conserved. The minimum energy required to take apart the nucleus is exactly the same as you get when you assemble it. From that standpoint it would take no extra energy at all. The minimum energy to take apart the nucleus is given by the binding energy. This being science (you should try it sometime) we can calculate the binding energy of U-238. It's about 1.8 GeV. (The difference between the mass of the constituent particles and the mass of the U-238, multiplied by c^2). Since some of the hydrogen would have to be deuterium and tritium, owing to all the extra neutrons, it would take even less energy than this to break the Uranium up into hydrogen.

 

That means you're off by at least 44 orders of magnitude . (there are 6.24 x 10^9 GeV/Joule) That's not typically considered "approximately correct"

I was thinking ionic binding breakoffs Also with the environment needed to do such a thing it would be something like my figure or am I chasing a non-existent wild goose?

Edited December 10, 2015 by TJ McCaustland

[MigL]

Don't know about geese,

but I hear a quack.

 

( just kidding TJ MC, I just couldn't resist )

Edited December 11, 2015 by MigL

[Sorcerer]

Component of matter. I am not trying to nitpick but even by that description it meets what I say. I am not calling quarks nothing. They are definitely the BUILDING blocks of matter. But not actually matter.

In a way they're not even blocks, they don't exist singularly, but as a descriptive component of hadrons. It just happens that hadrons can be described as having varying combinations of quarks. Quarks are more a shared property of hadrons, a derived measure of similarities.