Can Matter be Created or Destroyed?

[Alex K]

Also, yes, they don't necessarily meet

[Rhondazvous]

Oh yes it did!

No, the nucleus is the source of one of the photons. You would draw it as an X at its end or as a thick line running parallel all the way from left to right

Somebody told me to have a good day this morning. So despite the fact that I am now completely confused, I will hold on to that thought.

Nucleus is the source of one of the photons? I have been laboring under the impression that the nucleus came from some heavy atom such as lead or gold. How can such materials produce photons?

Please disabuse me and let me know what role lead or gold might play in a particle collider.

[Edwardo Piet]

@ Quantum

---

My guess is:

Matter can be created, and it was created during the "Big Bang." I also believe that a reversal of the process, in theory, would be an example of matter being destroyed.

You are talking about the dreaded Gnab Gib here, right...

Whether that is possible in practice perhaps depends on whether the Big Crunch will ever happen. According to Lawrence Krauss it will not, the Universe will keep expanding forever and ever.

According to almost everyone else as well. It's not so much about Lawrence Krauss' opinion, he simply recounts the current scientific consensus here. The crucial issue is about the nature of Dark Energy. If the observed Dark Energy simply takes the form of Einstein's cosmological constant, it always remains the same, as the term "constant" implies. If it remains the same in magnitude, forever it will dominate our destiny - as everything else gets diluted down by the expansion, the cosmo constant prevails unchanged, driving our universe towards eternal exponential expansion. Noone can currently know (for lack of empirical evidence) whether Dark Energy truly is  this simplest of all versions or something more complicated, but Occam's razor would suggest that if there is such a trivially simple explanation for the data, we should consider it likely.

So I would say I reckon matter can be created, but not destroyed - assuming Lawrence Krauss is right.

If you like you should read an article on inflation and reheating, to get an idea how matter might have been created from a different form of energy.

Energy however, I believe is eternal. Something must have always existed because it doesn't make sense for "nothing" to exist.

How do you define energy?

It is possible for "empty space" to exist, but that is actually something, just barely. It exists as something at least on the subatomic level. And that is where the title of the book "A Universe From Nothing" by Lawrence Kraus is a misnomer (It should really be called "A Universe From "Empty space"  Which Is Almost Nothing But Actually Just Barely Something At least On The Subatomic Level." - but that wouldn't be a very catchy title now would it? ). Although the science itself I am sure is very accurate.

Yes, I think the name is unfortunate, but if you want to sell, you need something catchy, and this stuff is something publishers love.

Energy cannot be created or destroyed. Matter can be created, and may or may not be able to be destroyed.

Why the distinction between matter and energy here? When you say matter cannot be destroyed, do you mean baryonic matter remains because of baryon number conservation?

---

Excellent post, kudos.

I found out about the theory of the universe expanding forever, as oppossed to the "Big Crunch" theory, via Lawrence Krauss.

I was unsure what the scientific consensus was. Thanks for letting me know.

I am defining "energy" as "something(s) or stuff that is existent". I just couldn't think of a word for that.

So my point is that matter is defined as some specific type of existent substance, whether it be dark matter or any other form of matter.

I used "energy" to include everything else existent, both that which is matter and that which is not. 

I guess it was merely to encompass physicality that is considered "immaterial".

Basically, the idea of nothing material existing makes sense if "material" is defined in a specific scientific way. But the idea of nothing at all existing makes no sense at all.

An analogy would be that the idea of something beyond the scientific definition of an "atom" existing makes perfect sense, and so does the idea of splitting it into smaller parts. But the idea of something beyond the original Ancient Greek philosophical definition of an "atom" (formulated by  Leucippus and Democritus) existing makes no sense and all, and neither does the idea of splitting it into smaller parts.

Pity that "atom" is usually assumed to mean the scientific version by default, because the original philosophical definition would be the perfect to encompass the meaning of "something existent". Then I wouldn't be using "energy" so vaguely.

[Rhondazvous]

Oh yes it did!

No, the nucleus is the source of one of the photons. You would draw it as an X at its end or as a thick line running parallel all the way from left to right

Somebody told me to have a good day this morning. So despite the fact that I am now completely confused, I will hold on to that thought.

Nucleus is the source of one of the photons?  I have been laboring under the impression that the nucleus came from some heavy atom such as lead or gold. How can such materials produce photons?

Please disabuse me and let me know what role lead or gold might play in a particle collider.

So you're just going to leave me in a state of confusion?

Boohoohoo, He doesn't love me anymore. crying my heart out.

[Alex K]

Love is a delicate flower. Also, I haz been busy cooking for the fam. Anyways
Trying to turn feynman theory into language now:
Anything that has electrical charge is constantly surrounded by a cloud of virtual photons which can meet up with another incoming particle to do something exciting. Nuclei for example carry positive charge. They are particularly useful as a scattering partner in this kind of experiment because they are heavy and can catch a lot of recoil without just being kicked away.

Now, the reason why nuclei such as lead are used in the LHC from time to time is quite different. One simply wants to collide a lot of particles to generate a subatomic hot soup in order to study new states of matter. So heavy nuclei with their dozens of protons and neutrons provide enough material for that. Also, they can be nicely accelerated due to being electrically charged.

[Rhondazvous]

Thanks. I think you've given me enough info to understand what I need to do regarding the collider. I will have a whole scene with the particles doing their dance in their while the photons are turning into e+ e- pairs.

Do what you have to do. Be sure to find some time in there to write your book.

[vorlon13]

Wanna go into the information paradox ??

Like, what if (thought experiment time) as much of the mass of the universe as possible is converted to energy (via black holes, proton decay, anti-matter, whatever it takes) and the universe continues to expand for a Skewes number taken to the Skewes number power a Skewes number of times years (that is one motherfucking big number of years, BTW) and all that energy is diluted and redshifted for that period.

So, how do we look at that final state (which actually isn't all that final and it still continues onward) in regards to the information paradox ?

[Alex K]

Vorlon,

are you implying that the information is gone because it gets diluted?

[vorlon13]

Vorlon,

are you implying that the information is gone because it gets diluted?

Diluted and redshifted into 'oblivion'.


 I'm conflating (equating) diluted and redshifted to that enormous extent so as to constitute actual erasure.  What would 'information' even mean in a universe as dissipated as I invoked ??

[Alex K]

Hmmm. The black hole information paradox I think is invoked because it seems to break the quantum evolution of the system via schrödinger's equation because the black hoe apparently converts a pure quantum state into a statistical mixture via hawking radiation. Simply diluting arbitrarily thinly would at no point give you this problem as far as I know, but if you would do the transition to total erasure, that would then violate it. An interesting question I have never wondered about is whether cosmic horizons which are caused by the expansion, can also lead to some sort of information problem.