Density

[jajrussel]

Maybe I am over simplifying, but the concept of density seems simple enough. Take an specific volume of space, add 1 thing to it, and the density for that volume changes.

 

It seems to me that with this concept under the right conditions we could conceivably have a volume of space, of anything, that presents the density of a brick, ( picked arbitrarily ).

 

If my thinking is correct even mass less particles without regard to the probability of the event occuring, should under the right conditions be capable of presenting a volume density comparable to, but not limited to that of a brick?

 

Is this correct?

[TheGeckomancer]

There have been experiments done, that have not been verified at all, still really new, where they were supposedly able to generate mass from photon interactions. "Illusory mass". Mind you this is mostly unverified like I said, the theory is sound to an extent but demonstrations are in short order.

 

http://phys.org/news/2013-09-scientists-never-before-seen.html

[jajrussel]

There have been experiments done, that have not been verified at all, still really new, where they were supposedly able to generate mass from photon interactions. "Illusory mass". Mind you this is mostly unverified like I said, the theory is sound to an extent but demonstrations are in short order.

 

http://phys.org/news/2013-09-scientists-never-before-seen.html

This is an interesting article, and pretty much a conversation in itself. It also reminds me that I have thought of virtual mass before when wondering why photons display gravitational interactions.

 

They in the article create a special situation, but I have wondered if the photons that allow me to see a tree are truly reflected, or does the original interaction, cause a photon to be emitted which allows me to see the tree? Or when a photon enters a medium is the photon that exits the medium the same photon for the same reason?

Edited November 27, 2015 by jajrussel

[TheGeckomancer]

Also. This is more a side effect of interactions of photons with matter. I would suggest for a much more interesting read in the Breitt-Wheeler process.

 

http://iopscience.iop.org/article/10.1088/1742-6596/497/1/012016/pdfThe math is a beast but you can ignore it and still get some usefulness from this.

http://www.gizmag.com/experiment-to-turn-light-into-matter/32107/Much simpler article on the matter

 

This is also much less speculative, while the test hasn't been done the math has been confirmed dozens of times.

Edited November 27, 2015 by TheGeckomancer

[Sensei]

Massless particle means particle that has no rest-mass. Not that it has no mass. It has relativistic mass.

(now will jump in people who are interpreting rest-mass and relativistic-mass differently)

If massless particle is absorbed total mass-energy of particle/object that absorbed it, is increased.

Reversing it, if massive particle is decaying to massless particles,

like f.e. [math]\pi^0 \rightarrow \gamma + \gamma[/math]

Total energy of produced photons is equal to total energy of pion prior decay.

[math]e^+ + e^- \rightarrow \gamma + \gamma[/math]

Total energy of produced photons is equal to total energy of electron and positron prior annihilation. Including their kinetic energies.

So black hole that is "sucking in" photons is increasing its mass.

Stars are emitting photons all the time, which have source in fusion, and losing their mass.

Before fusion protons to He-4, protons have 4*938.272 MeV/c^2, after fusion He-4 nucleus has 3727.38 MeV/c^2, star lost +-25.7 MeV mass-energy (part taken by neutrinos).

That's little more than 0.5%.

[studiot]

Useful summary Sensei, +1

[jajrussel]

Maybe I am over simplifying, but the concept of density seems simple enough. Take an specific volume of space, add 1 thing to it, and the density for that volume changes.

 

It seems to me that with this concept under the right conditions we could conceivably have a volume of space, of anything, that presents the density of a brick, ( picked arbitrarily ).

 

If my thinking is correct even mass less particles without regard to the probability of the event occuring, should under the right conditions be capable of presenting a volume density comparable to, but not limited to that of a brick?

 

Is this correct?

I was reading another thread that touched dark energy, black hole interaction, among other things. Which led to my thinking and asking these questions of density.

 

One of my thoughts was that I can understand the need for an additional sorce that displays gravity, and usually there are two mentioned, dark energy, and dark matter. In another thread it was said that energy is a property, not a substance. If this is true then dark energy would seem to need a substance in order to be displayed as a property.

 

Truthfully, I was thinking of dark energy as a substance. Dark energy as a property changes the thinking. Originally I had been wondering why the universe needed both dark energy, and dark matter, and if they both existed why would they need to be related.

 

I was viewing dark energy as a substance that might display as matter only under certain special circumstances. Such as extreme density brought about by the only property that seemed apparent, gravity.

 

If I want to continue the thought. I need to stop thinking of it as dark energy because energy is a property, and start thinking of it as a dark substance that only under special circumstances displays both gravity, and perhaps among other things the density of a brick.

 

I have chosen the word substance over matter because it seems assuming one to be the other is best not done.

 

But, are my thoughts about density correct?

Edited November 29, 2015 by jajrussel

[jajrussel]

I've started reading about this, and now I'm thinking I should have started reading more about it before I asked.

[swansont]

But, are my thoughts about density correct?

 

Density is usually applied to objects or materials, rather than arbitrary volumes, but there might be circumstances where that could be useful. There's nothing inherently wrong with it.

There have been experiments done, that have not been verified at all, still really new, where they were supposedly able to generate mass from photon interactions. "Illusory mass". Mind you this is mostly unverified like I said, the theory is sound to an extent but demonstrations are in short order.

 

http://phys.org/news/2013-09-scientists-never-before-seen.html

 

Addition or ejection of a photon changing the mass of the object has been verified. An isomer of an Iron isotope ion in a Penning trap was found to have a different mass than the ground state. That was a difference of less than half an MeV.

 

http://blogs.scienceforums.net/swansont/archives/278