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Author Topic: Can electrons and positrons interacting be used as a light source?  (Read 1300 times)

Offline thewonderer

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Ok, so I was wondering if we could use the energy given off by electrons and positrons colliding for light because I was searching the web and everywhere I looked said that they obliterate each other and give off energy and some said that they gave off gamma rays, so I was just wondering
« Last Edit: 03/01/2014 08:37:12 by chris »


 

Offline Ethos_

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Re: positrons
« Reply #1 on: 30/12/2013 22:05:18 »
Ok, so I was wondering if we could use the energy given off by electrons and positrons colliding for light because I was searching the web and everywhere I looked said that they obliterate each other and give off energy and some said that they gave off gamma rays, so I was just wondering
Consider this my friend;

All the energy we have available was created for us at the big bang. In effect, we are only able to use effectively what was originally provided for us at that moment in history. Because mass and energy are equivalent, we are also able to extract energy from available mass. But the available mass we have to work with is also limited to the amount created at the big bang.

My point is this: We can't create new mass/energy, we can only use the limited supply that the big bang gave us. We are able to transform one to the other but we can't create new mass/energy. While it is true that electron positron annihilation liberates vast amounts of energy, it is also true that as we speak, it requires much more energy to create the positron than what we can extract from the annihilation process. In short, it isn't a practical source of energy. Remember, we can't create new mass/energy, we can only use the limited amount the big bang gave us.
 

Offline evan_au

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Re: positrons
« Reply #2 on: 30/12/2013 22:36:51 »
The collision of an electron and positron does give off energy in the form of gamma rays. However, this is penetrating ionising radiation that can damage DNA, and so there would need to be some compensating medical benefit for it to be used near humans, such as with PET scans.

It is not really possible to "tone down" the gamma ray energy to something which is safe for humans (except perhaps by extreme cosmological redshift...). However, it is a useful tool for scientists.

In general, matter/antimatter reactions such as electrons/positrons or protons/antiprotons are the most energetic reactions known, and antimatter fuel would be very effective for use in spaceships, since it carries considerable energy for its mass. Despite movies like "The Da Vinci Code", we know of no efficient way of producing antimatter in practical amounts, transporting it safely, or of releasing its energy in ways that can be usefully harnessed.

Which is probably just as well, since
Quote from: Lord Acton
Power tends to corrupt, and absolute power corrupts absolutely.
...and antimatter is potentially a source of immense power.
 

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Re: positrons
« Reply #2 on: 30/12/2013 22:36:51 »

 

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