Virtual Particles are not Dark Matter?

[HexHammer]

TL;DR

Virtual Particles

So far as I understand it, a photon can split up and create particles with matter, even though the photon is massless, yes?

So if a photon can be more places at the same time, it should be able to create multiple particles all at once?

So how is this not Dark Matter?

 

[Halc]

So far as I understand it, a photon can split up and create particles with matter, even though the photon is massless, yes?

Something like that, yes. It doesn't just happen in the middle of nowhere. The photon needs to have enough energy to create the mass of the pair (energy/mass equivalence), and there needs to be something else nearby involved in the event (typically a nucleus of some kind) to allow momentum to be conserved.
These are not virtual particles (mentioned in the title but not in the post). Both particles created are quite real, as was the photon.

So if a photon can be more places at the same time

They can't. They don't really have a place that they occupy at all until they are measured, that is until they interact with something. When they do that, they cannot react elsewhere, so no measuring a photon in two different places.

So how is this not Dark Matter?

Photons, electrons and positrons are all very detectable, not dark at all.

 

[PeterDonis]

a photon can split up and create particles with matter, even though the photon is massless, yes?

One photon can't, because there is no way for one massless photon to split into two particles each with nonzero rest mass that will conserve both energy and momentum.

Two photons can collide and produce two particles each with nonzero rest mass, but the energy density has to be very, very high (as in, the kind of energy density that only existed in the very early universe) for this to occur with appreciable frequency.

 

[Dale]

So how is this not Dark Matter?

How are particles of light not dark matter? Really?

 

[HexHammer]

Thanks for answer guys, how quantum physics are confusing!

 

[HexHammer]

They can't. They don't really have a place that they occupy at all until they are measured, that is until they interact with something. When they do that, they cannot react elsewhere, so no measuring a photon in two different places.

That sounds like it conflicts with the concept of "superposition" where the photon in the famous "double slit experiment" can go through both slits, through either or none at the same time?

 

[HexHammer]

One photon can't, because there is no way for one massless photon to split into two particles each with nonzero rest mass that will conserve both energy and momentum.

Two photons can collide and produce two particles each with nonzero rest mass, but the energy density has to be very, very high (as in, the kind of energy density that only existed in the very early universe) for this to occur with appreciable frequency.

The man in the video says that gamma ray photons has enough energy to do it?

 

[Halc]

That sounds like it conflicts with the concept of "superposition" where the photon in the famous "double slit experiment" can go through both slits, through either or none at the same time?

Superposition isn't "actually being in two places", so a photon, lacking a measured position, does not actually go specifically through either slit. In some realist interpretations, the photon does have a position unmeasured, and actually goes through one slit or the other, and still isn't in two places at once.

I of course wasn't speaking of superposition, since once measured, the photon's position isn't in superposition anymore. A photon that undergoes pair production isn't in superposition anymore, at least relative to the produced pair and anything that inevitably measures one or the other of the pair.

 

[PeterDonis]

The man in the video

In the video, the photon is not getting converted to an electron-positron pair on its own. It is hitting a block of some material, and the electron and positron are coming out of the material. That process is not the same as "a photon splitting up and creating particles of matter".

 

[PeterDonis]

The OP question has been answered. Thread closed.