Matter-antimatter annihilation

  • Thread starter GRB 080319B
  • Start date
  • Tags
    Annihilation
In summary: Entropy, as I understand it, is a time biased quantity, which can increase or stay the same in a system as time moves forward. Does this mean that matter-antimatter annihilation is a reversible reaction and that subatomic particles aren't biased by the direction of time(like macroscopic objects are)? Yes, matter and antimatter can annihilate each other in a process that produces energy, but it is not 100% efficient. The conversion of matter into energy in the accretion disk of a black hole is the most efficient system observed, but even black holes release a small amount of energy as heat and particles into the surrounding universe. Can these reactions reduce the entropy of a system?In principle, yes, but
  • #1
GRB 080319B
108
0
Why, or perhaps how, is 100% of the mass in matter-antimatter annihilation turned into energy? I thought no reaction could be 100% efficient, i.e. 2nd law of thermodynamics? Isn't the Carnot heat engine or the conversion of matter into energy in the accretion disk of a black hole the most efficient systems observed? Entropy, as I understand it, is a time biased quantity, which can increase or stay the same in a system as time moves forward. Does this mean that matter-antimatter annihilation is a reversible reaction and that subatomic particles aren't biased by the direction of time(like macroscopic objects are)? Can these reactions reduce the entropy of a system? I believe that I may be missing out on a fundamental aspect of the physics underlying this reaction.
 
Physics news on Phys.org
  • #2
The 2nd law of thermodynamics doesn't just fall out of any microscopic theory of a few particles, whether it is your exotic matter/anti-matter example or whatever else. Entropy is a quantity that only makes sense in macroscopic systems.

Same goes for all the other question in your post. Maybe ask again in the condensed matter section.
 
  • #3
olgranpappy said:
Entropy is a quantity that only makes sense in macroscopic systems.

This links describes a type of entropy occurring in quantum mechanics: http://en.wikipedia.org/wiki/Von_Neumann_entropy" [Broken]

Does this have anything to do with the questions I presented?

olgranpappy said:
Maybe ask again in the condensed matter section.

Would it be possible to move this entire thread to the condensed matter section? If so, how?
 
Last edited by a moderator:
  • #4
GRB 080319B said:
This links describes a type of entropy occurring in quantum mechanics: http://en.wikipedia.org/wiki/Von_Neumann_entropy" [Broken]

Does this have anything to do with the questions I presented?

The link shows a definition of the entropy of a system in terms of the density matrix which desribes the system. And there is other stuff shown on the linked page. Yes, the link is vaguely related to your first post.

Would it be possible to move this entire thread to the condensed matter section? If so, how?

I don't know. If I were you I would just take some time and think about your own question and then rephrase and revamp the question and start a new thread. It is an interesting question, but I think there have been several similar questions that you can find by searching the threads here (sorry, I don't have a link). After reading other threads and other responses you will be able to ask a better and more thoughtful question that gets better and more thoughtful responses from the forum scientists.
 
Last edited by a moderator:
  • #5
Why, or perhaps how, is 100% of the mass in matter-antimatter annihilation turned into energy? I thought no reaction could be 100% efficient, i.e. 2nd law of thermodynamics?
The laws of thermodynamics, as is pointed out above, relate to heat exchange processes taking place in bulk. The theorem you quote is about extracting mechanical energy from hot gases, or heating or cooling matter.

When an electron and a positron interact to make light, these laws are irrelevant. 100% of both particles becomes energy.

You're applying bulk theorems to quantum-mechanical point processes.
 
  • #6
Also, matter/anti-matter anihilation on a large scale would not be 100% efficient. Lots (perhaps 50%) of the energy would be released as neutrinos, which are for all practical purposes worthless. All of the actual photons released would, as soon as they interacted with matter, likewise be affected by entropy. Much of the energy would become heat and (if the reaciton happened in the atmosphere) sound as well.

So you could never get 100% efficiency from an antimatter power generator or antimatter weapon, or anything else involving antimatter on a macroscopic scale. Although, as others have said, on a microscopic scale, ie one annihilated pair at a time, entropy does not factor into isolated reactions, even a single photon will eventually give way to entropy, once that photon has been detected or has interacted with anything else in the macro world.
 

What is matter-antimatter annihilation?

Matter-antimatter annihilation is a process in which particles of matter and antimatter collide and completely convert into energy. This process is governed by Einstein's famous equation, E=mc^2, where E represents energy, m represents mass, and c represents the speed of light.

Why is matter-antimatter annihilation important?

Matter-antimatter annihilation is important in understanding the fundamental nature of the universe and the laws of physics. It also has potential applications in energy production and propulsion in space travel.

How does matter-antimatter annihilation occur?

Matter-antimatter annihilation occurs when particles of matter and antimatter come into contact with each other. When this happens, they annihilate each other and produce high-energy photons or other particles as a result.

What happens to the energy produced during matter-antimatter annihilation?

The energy produced during matter-antimatter annihilation is released in the form of high-energy photons, which can then be converted into other forms of energy, such as heat or electricity.

Can we harness the energy from matter-antimatter annihilation?

While it is theoretically possible to harness the energy from matter-antimatter annihilation, it is currently not a practical or efficient source of energy due to the difficulties in producing and containing antimatter. However, research and experiments are ongoing to explore the potential of this process in energy production.

Similar threads

  • Quantum Physics
Replies
2
Views
2K
  • Astronomy and Astrophysics
Replies
4
Views
2K
  • Other Physics Topics
Replies
1
Views
12K
  • Quantum Physics
2
Replies
39
Views
2K
Replies
17
Views
9K
  • High Energy, Nuclear, Particle Physics
Replies
2
Views
2K
  • High Energy, Nuclear, Particle Physics
Replies
21
Views
3K
Replies
10
Views
2K
Replies
3
Views
1K
Replies
8
Views
1K
Back
Top