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Poc ar buile
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#21
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#21
(Original post by elpaw)
what practical use is there for the tau neutrino or the strange quark?

positrons are theorised (in one of feynmann's theories) to be tachyonic electrons
Strange matter exists in abundance in many places in the universe, does it not?

Tau neutrinos are inportant in the decomposition of tauons/anti-tauons, I'd guess...

How can we observe/form positrons (entering medical student mode - for use in PET, for example) if they are tachyons? That sounds highly unlikely to me, but I'm not a physicist - so I may well be wrong.
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dinkymints
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#22
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#22
I'd love to be able to understand all this!!
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Poc ar buile
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#23
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#23
(Original post by dinkymints)
I'd love to be able to understand all this!!
Does anyone at all?!? :confused:
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Nylex
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#24
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#24
(Original post by polthegael)
Does anyone at all?!? :confused:
Bits, though I don't know what tachyons are or what elpaw meant by 'faster than light travel is possible as long as you don't cross the light barrier' .
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Poc ar buile
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#25
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#25
(Original post by Nylex)
Bits, though I don't know what tachyons are or what elpaw meant by 'faster than light travel is possible as long as you don't cross the light barrier' .
A tachyon is a theorised particle which travels faster than the speed of light and cannot be slowed down to the speed of light.

The speed of light in a vacuum is therefore a sort of assymptote. It can be approached from either side, but not touched.

I'd query why you'd want to travel faster than light speed if you then couldn't slow down again (not that you could get up to it in the first place unless you have always had that really fast speed!)...
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Willa
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#26
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#26
the solution to his apple problem is such:

if you fire your apple at 99% speed of light, and then blast it in half, the half an apple would acclerate to about 99.5% the speed of light. the extra 0.5% would significantly increase the mass of the apple due to relaitivity (as you approach the speed of light the rate of change of mass with respect to velocity increases to infinite, so when you reach 99.9999999999% the speed of light, you require an infinite amount of energy to get that last little bit of velocity).

Tachyons are theoretical, nobody has found them yet. They could exist, it's just hard to detect em.

Sub note: Faster than light travel has already been accomplished. Obviously though, not in a vacuum. Using optical liquids light can be sufficiently slowed down so that electrons and stuff travel through faster than the speed of the light. When this happens you get a "Solar Boom" just like a "sonic boom" but with light, where the thing goes ridiculously bright! I cant remember the name of the effect, but you can find it on the net, i'm just too lazy!
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Poc ar buile
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#27
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#27
(Original post by Willa)
Sub note: Faster than light travel has already been accomplished. Obviously though, not in a vacuum. Using optical liquids light can be sufficiently slowed down so that electrons and stuff travel through faster than the speed of the light. When this happens you get a "Solar Boom" just like a "sonic boom" but with light, where the thing goes ridiculously bright! I cant remember the name of the effect, but you can find it on the net, i'm just too lazy!

I think I've probably mentioned it already here... It's Cerenkov radiation...
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rts
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#28
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#28
(Original post by polthegael)
How can we observe/form positrons (entering medical student mode - for use in PET, for example) if they are tachyons? That sounds highly unlikely to me, but I'm not a physicist - so I may well be wrong.
This is the same thing we were talking about in the other thread. Feynman said particles going forward in time behave identically as their anti-particles going backwards in time. So a positron is the same as an electron travelling in the opposite time direction, and vice versa.
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jpowell
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#29
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#29
(Original post by elpaw)
positrons are theorised (in one of feynmann's theories) to be tachyonic electrons
Eh? Positrons are quite real and certainly do not travel faster than the speed of light. Radioactive nuclei produce them all the time, and they can be collected and observed, and do not appear to be going faster than the speed of light. Maybe you might want to rephrase that?
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Squishy
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#30
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#30
One of my favourite Futurama moments:

Farnsworth: These are the dark matter engine I invented. They allow my starship to travel between galaxies in mere hours.

Cubert: That's impossible. You can't go faster than the speed of light.

Farnsworth: Of course not. That's why scientists increased the speed of light in 2208.

Cubert: Also impossible.

[Scene: Ship's Engine Room. Farnsworth admires the dark matter engines.]

Farnsworth: And what makes my engines truly remarkable is the afterburner which delivers 200% fuel efficiency.

Cubert: That's especially impossible.

Farnsworth: Not at all. It's very simple.

Cubert: Then explain it.

Farnsworth: Now that's impossible. It came to me in a dream and I forgot it in another dream.
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elpaw
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#31
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(Original post by AntiMagicMan)
Eh? Positrons are quite real and certainly do not travel faster than the speed of light. Radioactive nuclei produce them all the time, and they can be collected and observed, and do not appear to be going faster than the speed of light. Maybe you might want to rephrase that?
sorry, electrons travelling back in time. look above your post
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jpowell
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#32
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Ah, okay .

You can only really apply that interpretation on the quantum scale though if I remember correctly?
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Euler
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#33
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#33
helpful link on this topic...


http://www.angelfire.com/nj/FTLphysics/index.html
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