Science > Physics > Tachyons negative energy and moving backwards in time
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Science > Physics |
| User: |
"Kalikinkar" |
| Date: |
08 Feb 2005 05:34:14 AM |
| Object: |
Tachyons negative energy and moving backwards in time |
Particles cannot pass the velocity-barrier represented by the velocity
of light. However, the special theory of relativity permits the
existence of particles that have always moved with a velocity v >c .
Such particles, tachyons, have special properties that have been used
in the experimental searches for them. Is there any observational
evidence for the physical existence of tachyons?
There are also certain theoretical difficulties with the existence of
tachyons I guess. The special theory of relativity, applied to tachyons
leads to the following paradox. Using a tachyon telephone a person, A ,
emits a tachyon to B at a point of time t1. B moves away from A . The
tachyon is reflected by B and reach A before it was emitted. If the
tachyon could carry information it might bring an order to destroy the
tachyon emitter when it arrives back at A. To avoid similar problems in
regards to the energy-exchange between tachyons and ordinary matter, a
reinterpretation principle is introduced for tachyons. For certain
observers a tachyon will move backwards in time, i.e. the observer
finds that the tachyon is received before it was emitted. Special
relativity tells us that such a tachyon is always observed to have
negative energy. According to the reinterpretation principle, the
observer will interpret his observations to mean that a tachyon with
positive energy moves forward in time. Any thoughts on tachyons,
negative energy and moving backwards in time?
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| User: "John Zinni" |
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| Title: Re: Tachyons negative energy and moving backwards in time |
08 Feb 2005 10:13:51 AM |
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"Kalikinkar" <kalikinkar@gmail.com> wrote in message
news:1107862454.463552.322900@c13g2000cwb.googlegroups.com...
Particles cannot pass the velocity-barrier represented by the velocity
of light. However, the special theory of relativity permits the
existence of particles that have always moved with a velocity v >c .
Such particles, tachyons, have special properties that have been used
in the experimental searches for them. Is there any observational
evidence for the physical existence of tachyons?
Baltay et al. 1970, Search for Uncharged Faster-than-Light Particles,
PhRvD..1..759
"An experiment has been carried out to search for uncharged particles with
spacelike four-momentum which presumably travel faster than light. No
evidence for such particles has been found."
Smith & Standil 1977, Search for tachyons preceding cosmic ray extensive air
showers of energy greater than about 10 to the fourteenth eV,
CaJPh..55..1280
"No convincing evidence was found for any subgroup of these events that
might be attributable to tachyons."
Bartlett et al. 1978, Search for tachyon monopoles in cosmic rays,
PhRvD..18..2253
"In summary we have found no evidence for tachyon monopoles that either emit
Cerenkov radiation in air or ionize matter."
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| User: "RipVanWinkle" |
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| Title: Re: Tachyons negative energy and moving backwards in time |
08 Feb 2005 07:51:53 AM |
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Kalikinkar wrote:
Particles cannot pass the velocity-barrier represented by the
velocity
of light. However, the special theory of relativity permits the
existence of particles that have always moved with a velocity v >c .
Such particles, tachyons, have special properties that have been used
in the experimental searches for them. Is there any observational
evidence for the physical existence of tachyons?
There are also certain theoretical difficulties with the existence of
tachyons I guess. The special theory of relativity, applied to
tachyons
leads to the following paradox. Using a tachyon telephone a person, A
,
emits a tachyon to B at a point of time t1. B moves away from A . The
tachyon is reflected by B and reach A before it was emitted. If the
tachyon could carry information it might bring an order to destroy
the
tachyon emitter when it arrives back at A. To avoid similar problems
in
regards to the energy-exchange between tachyons and ordinary matter,
a
reinterpretation principle is introduced for tachyons. For certain
observers a tachyon will move backwards in time, i.e. the observer
finds that the tachyon is received before it was emitted. Special
relativity tells us that such a tachyon is always observed to have
negative energy. According to the reinterpretation principle, the
observer will interpret his observations to mean that a tachyon with
positive energy moves forward in time. Any thoughts on tachyons,
negative energy and moving backwards in time?
Einstein energy equation: E =3D mc 2 /=83.
The factor =83 is
=83 =3D sqrt[1 - (v/c)2 ]
and it goes to zero when v =3D c.
But suppose v is greater than c.
Then =83 is the square-root of a negative number.
That makes the energy factor =83 imaginary, right?
Right. Doesn't that make the energy E imaginary too?
The surprising answer is: not necessarily.
Suppose there were a particle that had imaginary mass.
I know - now you are completely confused.
Does a particle with imaginary mass mean that the particle doesn't
really exist?
Is it imaginary?
If you've never felt comfortable with "imaginary" numbers,
don't worry.
Stick with me, and learn the conclusions,
if not the logic that we use to get there.
The two imaginary numbers,
the mass and =83,
when multiplied together,
create a real number.
That means that everything works out OK.
We can re-write the energy equation in terms of real numbers.
Let the mass of the tachyon be (i m0),
where i is the square-root of -1,
and m0 is a real number.
Then, for a tachyon, the two values of i will cancel, and
we'll get:
E =3D m0 c 2 /sqrt[(v/c)2 - 1]
This is the tachyon energy equation.
When v becomes infinite, the energy E goes to zero.
And when v is equal to c, the energy E is infinite.
If you think that is weird, be assured that everyone else thinks so
too.
But that doesn't prevent it from being true.
Well a tachyon is a particle
(not yet discovered, although people have looked) that
travels faster than the speed of light.
But how can you get it going that fast?
Doesn't it have to start at rest,
and so it would take infinite energy to get just up to c -
and therefore it could never go beyond?
No - tachyons are assumed to be born fast.
Photons are never accelerated up to light speed;
they start out that way. If tachyons can be created, when
they are created they already have speed faster than c.
They can lose energy by speeding up,
or gain energy by slowing down.
(Note that that is backwards from the way ordinary
particles such as electrons behave.)
Tachyons may exist,
and from time to time,
physicists set up experiments to search for them.
However, I do not think they will find them.
The reason has to do with another property of relativity,
having to do with the simultaneity of events.
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| User: "Sam Wormley" |
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| Title: Re: Tachyons negative energy and moving backwards in time |
08 Feb 2005 08:21:53 AM |
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Kalikinkar wrote:
Particles cannot pass the velocity-barrier represented by the velocity
of light. However, the special theory of relativity permits the
existence of particles that have always moved with a velocity v >c .
Such particles, tachyons, have special properties that have been used
in the experimental searches for them. Is there any observational
evidence for the physical existence of tachyons?
No
Ref: http://www.csicop.org/sb/9409/reality.html
Reality Check - Tachyons and Other Nonentities
Sliding (faster than a beam of light) across my desk recently came a
copy of a full-page ad that had appeared in a journal called Pacific
Spirit. The heading on this page is: "TACHYON: YOUR HEALTH AND
FITNESS ARE IN YOUR HANDS." It begins: "Subtle Energy That Relates
to Your Body At Its Highest Level of Vibration. Tachyon comes from
the Greek word tachy which means acceleration. The name refers to
sub-atomic particles which travel faster than the speed of light.
Because of its speed, Tachyon can exist everywhere." There follow
advertisements for Tachyon Mineral Water, Tachyon Space Fiber Head &
Wristbands, Tachyon Jewelry Beads, etc., all of which are intended
to enhance your state of well-being, both physical and spiritual.
The prices are fairly modest.
What I like is the irrelevant logic. "Because of its speed, Tachyon
can exist everywhere." A non sequitur if I ever heard one. Before it
can exist anywhere, a tachyon must exist somewhere. And there's the
rub.
See: http://www.csicop.org/sb/9409/reality.html
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