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breaking the speed of light article on howstuffworks.com

S

~~SciGirl~~

Jan 1, 1970
0
I just read that article and decided to find more information on google
and found this group... I am 14 years old (yes, I do understand quantum
physics, relativity, and some of the uncertainty principle; I'm
obsessed with science). After reading the article "How Time Travel Will
Work" a few days ago, I was thinking and figured that the only thing
that would ever be able to travel beyond the speed of light without
being destroyed is light itself. Then today I read about that
experiment, and it supports what I thought. I do think it is possible
for light to travel faster than its own speed, and if this didn't occur
in the cesium-filled container it could occur in space, if wormholes
exist. There also is a logical explanation for why the light appeared
to exit the container before it entered. I found it searching Google.
If you think about it enough, you realize there cannot be a set speed
that nothing can travel beyond
 
S

~~SciGirl~~

Jan 1, 1970
0
Here it is, I located it again.

"In Wang's experiment, a pulse of light passed through a small
chamber filled with atoms of elemental cesium. A light beam traveling
through such a medium has two different velocities - a velocity for
the individual light waves in the beam and a group velocity for the
entire beam. Oddly, some light waves in the beam can actually travel
backward for miniscule amounts of time, creating a sort of "tail"
behind forward-moving waves. As such, a light wave and its tail can
leave the gas cavity at different times, creating the effect that the
light beam has left the cavity before it's even entered."
 
N

Nico Coesel

Jan 1, 1970
0
~~SciGirl~~ said:
Here it is, I located it again.

"In Wang's experiment, a pulse of light passed through a small
chamber filled with atoms of elemental cesium. A light beam traveling
through such a medium has two different velocities - a velocity for
the individual light waves in the beam and a group velocity for the
entire beam. Oddly, some light waves in the beam can actually travel
backward for miniscule amounts of time, creating a sort of "tail"
behind forward-moving waves. As such, a light wave and its tail can
leave the gas cavity at different times, creating the effect that the
light beam has left the cavity before it's even entered."

This sounds a lot like the electrical effects observed by our friend
Mathew Orman during his FTL dream.
 
C

Charles Schuler

Jan 1, 1970
0
If you think about it enough, you realize there cannot be a set speed
that nothing can travel beyond

You can realize anything but that does not mean that the physical universe
will ever cooperate with your musings.
 
J

John Larkin

Jan 1, 1970
0
This sounds a lot like the electrical effects observed by our friend
Mathew Orman during his FTL dream.


Same sort of thing, altering the shape of a pulse and thinking that
makes it go faster. Optically, an oscillatory burst can appear to
exceed C if you sort of stand back and squint, but no photons are
going faster than C.

John
 
F

Fred Bartoli

Jan 1, 1970
0
John Larkin said:
Same sort of thing, altering the shape of a pulse and thinking that
makes it go faster. Optically, an oscillatory burst can appear to
exceed C if you sort of stand back and squint, but no photons are
going faster than C.

Well, I've just done mucho faster than light with a 100kHz sine wave. Pretty
easy: don't terminate the line and once the transient is settled (which you
can't notice) the sine wave "travels FTL" (read the phase shift is much
smaller than what light speed would imply for the line length). Terminate
the line and the effect is gone.

This saved me on a precision phase measurement board.
 
W

Winfield Hill

Jan 1, 1970
0
Nico Coesel wrote...
This sounds a lot like the electrical effects observed by our
friend Mathew Orman during his FTL dream.

No, actually quite different.
 
K

keith

Jan 1, 1970
0
Same sort of thing, altering the shape of a pulse and thinking that
makes it go faster. Optically, an oscillatory burst can appear to
exceed C if you sort of stand back and squint, but no photons are
going faster than C.

I designed a logic level convert circuit once that I spec'd with a
negative delay, at least until someone read it. I was *forced* to do
rise-times from 20-80 and delays from 50-50. The threshold wasn't at 50,
so until I showed the PHBs how stupid their requirements were, it had a
negative delay. ...and no, no electrons were hurt in testing the circuit.
 
S

~~SciGirl~~

Jan 1, 1970
0
Mathew Orman, FTL dream? I must have missed something. Yes, I suppose
its true that "You can realize anything but that does not mean that the
physical universe will ever cooperate with your musings." After all, it
was considered common knowledge that a cause must always precede an
effect, yet it is believed the light left the tube before it entered.

All please note: I am only 14 and am one year ahead in math, the most I
know is basic algebra, so don't try to tell me anything with a lot of
equations as I will probably be unable to comprehend it. The one part
of all this I cannot yet understand is the math. No calculus, please.
 
S

~~SciGirl~~

Jan 1, 1970
0
As John Larkin said... "Same sort of thing, altering the shape of a
pulse and thinking that makes it go faster. Optically, an oscillatory
burst can appear to
exceed C if you sort of stand back and squint, but no photons are going
faster than C."

You can never be positive. If you cannot measure the position and
velocity of the photons simultaneously, how can you be sure they are
not going faster than c? Nobody can really measure the speed of the
particles as they exited the container, because you'd need to specify
the position defined as "exiting the container." This could disprove
the experiment, but it could also disprove the arguments of everyone
who does not believe the photons moved faster than c.
 
S

~~SciGirl~~

Jan 1, 1970
0
As John Larkin said... "Same sort of thing, altering the shape of a
pulse and thinking that makes it go faster. Optically, an oscillatory
burst can appear to
exceed C if you sort of stand back and squint, but no photons are going
faster than C."

You can never be positive. If you cannot measure the position and
velocity of the photons simultaneously, how can you be sure they are
not going faster than c? Nobody can really measure the speed of the
particles as they exited the container, because you'd need to specify
the position defined as "exiting the container." This could disprove
the experiment, but it could also disprove the arguments of everyone
who does not believe the photons moved faster than c.
 
~~SciGirl~~ said:
I just read that article and decided to find more information on google
and found this group... I am 14 years old (yes, I do understand quantum
physics, relativity, and some of the uncertainty principle; I'm
obsessed with science). After reading the article "How Time Travel Will
Work" a few days ago, I was thinking and figured that the only thing
that would ever be able to travel beyond the speed of light without
being destroyed is light itself. Then today I read about that
experiment, and it supports what I thought. I do think it is possible
for light to travel faster than its own speed, and if this didn't occur
in the cesium-filled container it could occur in space, if wormholes
exist. There also is a logical explanation for why the light appeared
to exit the container before it entered. I found it searching Google.
If you think about it enough, you realize there cannot be a set speed
that nothing can travel beyond

I suggest you look up Einstein's special theory of relativity. This is
not just "E=M(C squared)" (that is just the value of energy in matter,
and only at rest at that) it is the theory that explains why C is the
universal speed limit. Most of it can be understood without using
calculus if you find a decent book.
 
J

John Larkin

Jan 1, 1970
0
As John Larkin said... "Same sort of thing, altering the shape of a
pulse and thinking that makes it go faster. Optically, an oscillatory
burst can appear to
exceed C if you sort of stand back and squint, but no photons are going
faster than C."

You can never be positive. If you cannot measure the position and
velocity of the photons simultaneously, how can you be sure they are
not going faster than c? Nobody can really measure the speed of the
particles as they exited the container, because you'd need to specify
the position defined as "exiting the container."

You can build a fast shutter close to a source that only lets light
through for a nanosecond or less, and then measure arrival times some
distance away. Or do interferance experiments, which are exquisitely
sensitive to the speed of light. There are lots of techniques that
could detect ftl photons if they existed.

This could disprove
the experiment, but it could also disprove the arguments of everyone
who does not believe the photons moved faster than c.


Well, you can't disprove the conjecture that something, maybe a rogue
photon, does move ftl. But no experiment has ever demonstrated such,
and there's lots of theory that says it can't happen. The burden of
proof is to show a real case. "Laws" like the conservation of energy
get much of their force from the fact that no counter-case has ever
been observed.

You can observe a quasar flash that happened 8 billion years ago, on
the other side of this universe, and look at it in wavelengths from
radio through gamma rays; everything arrives at Earth at the same
time, which is pretty impressive.

John
 
B

Ben Bradley

Jan 1, 1970
0
Mathew Orman, FTL dream? I must have missed something.

Short story, he was a guy here telling about his cables he tried to
sell on ebay for an outrageous price, that he claimed could transmit a
signal faster than the speed of light.
Yes, I suppose
its true that "You can realize anything but that does not mean that the
physical universe will ever cooperate with your musings." After all, it
was considered common knowledge that a cause must always precede an
effect, yet it is believed the light left the tube before it entered.

All please note: I am only 14 and am one year ahead in math, the most I
know is basic algebra, so don't try to tell me anything with a lot of
equations as I will probably be unable to comprehend it. The one part
of all this I cannot yet understand is the math. No calculus, please.

Calculus isn't that bad, it's all about rate of change (at least
the differential part). I recall the teenage years as having a high
rate of change, so you should have no problem understanding it. :)
 
C

Clifford Heath

Jan 1, 1970
0
~~SciGirl~~ said:
If you think about it enough, you realize there cannot be
a set speed that nothing can travel beyond

Unfortunately for us, we naturally think in terms of linear
cubic space (Euclidian space in three dimensions). No matter
how much you think that way, it's impossible to visualise
an absolute speed limit - so you're right there.

The speed limit actually does exist however, because space
is curved and time dilates - the simple Euclidian model of
space is wrong. "Space tells matter how to move, and matter
tells space how to bend".
 
G

Gareth

Jan 1, 1970
0
~~SciGirl~~ said:
As John Larkin said... "Same sort of thing, altering the shape of a
pulse and thinking that makes it go faster. Optically, an oscillatory
burst can appear to
exceed C if you sort of stand back and squint, but no photons are going
faster than C."

You can never be positive. If you cannot measure the position and
velocity of the photons simultaneously, how can you be sure they are
not going faster than c? Nobody can really measure the speed of the
particles as they exited the container, because you'd need to specify
the position defined as "exiting the container." This could disprove
the experiment, but it could also disprove the arguments of everyone
who does not believe the photons moved faster than c.

Einstein's theory of Special Relativity prevents anything with mass or
information from travelling faster than light. It is possible that one
day this theory will be proved wrong, but it has been validated by many
experiments over the last 100 years. The FAQ on Wang's webpage states
that his experiment does NOT contradict current theory, and cannot be
used to send information faster than light. See:

http://www.neci.nj.nec.com/homepages/lwan/faq.htm

For a very good demonstration of how light can appear to travel faster
than light have a look at the Java applet in the link below:

http://gregegan.customer.netspace.net.au/APPLETS/20/20.html

The Java applet also shows what happens if you try to send information
by modulating the beam.

There is some more information on superluminal phenomena here:

http://scienceworld.wolfram.com/physics/Superluminal.html

Gareth.

--
 
W

Winfield Hill

Jan 1, 1970
0
Ben Bradley wrote...
Short story, he was a guy here telling about his cables he tried to
sell on ebay for an outrageous price, that he claimed could transmit
a signal faster than the speed of light.

Yes, he offered the original laboratory cable at a high price, as a
sort of historical valuable artifact, but at about the same time he
also offered a student cable for $10, IIRC. There were no bidders.
 
R

Robert Baer

Jan 1, 1970
0
Fred said:
Well, I've just done mucho faster than light with a 100kHz sine wave. Pretty
easy: don't terminate the line and once the transient is settled (which you
can't notice) the sine wave "travels FTL" (read the phase shift is much
smaller than what light speed would imply for the line length). Terminate
the line and the effect is gone.

This saved me on a precision phase measurement board.

Bullshit.
It is clear that you do not understand what you thought you saw.
 
R

Robert Baer

Jan 1, 1970
0
keith said:
I designed a logic level convert circuit once that I spec'd with a
negative delay, at least until someone read it. I was *forced* to do
rise-times from 20-80 and delays from 50-50. The threshold wasn't at 50,
so until I showed the PHBs how stupid their requirements were, it had a
negative delay. ...and no, no electrons were hurt in testing the circuit.

Sorry; even measuring from the 5% point of a rising input pulse, to
any part (5%, 50% or 95%) of the output pulse, one will see some
positive delay - even over a distance of an inch long micristrip.
Light (or RF or pulses) travel about 11 inches in a nanosecond or
roughly 9 inches in a coax cable.
If one is using two probes so to simultaneously "see" both signals,
one must first determine what distortions in waveform(s) and in time
they present to the scope or other measuring device.
TTL logic roughly has a 7nSec rise and fall, and delay roughly of
15nSec.
For reasonably accurate measurements of all of those parameters, one
should have a system with an accuracy better than 1nSec and correctable
errors (time differences) that are also better than 1nSec.
For measuring delay in a one inch microstrip, those values should be
less than 100pSec and better be known values if that large; it helps
greatly to have a rather fast rise and/or fall in the pulse that is
going to be measured (100pSec or better - and the values also known).
 
R

Robert Baer

Jan 1, 1970
0
Gareth said:
Einstein's theory of Special Relativity prevents anything with mass or
information from travelling faster than light. It is possible that one
day this theory will be proved wrong, but it has been validated by many
experiments over the last 100 years. The FAQ on Wang's webpage states
that his experiment does NOT contradict current theory, and cannot be
used to send information faster than light. See:

http://www.neci.nj.nec.com/homepages/lwan/faq.htm

For a very good demonstration of how light can appear to travel faster
than light have a look at the Java applet in the link below:

http://gregegan.customer.netspace.net.au/APPLETS/20/20.html

The Java applet also shows what happens if you try to send information
by modulating the beam.

There is some more information on superluminal phenomena here:

http://scienceworld.wolfram.com/physics/Superluminal.html

Gareth.

--
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Replace privacy.net with: totalise DOT co DOT uk and replace me with
gareth.harris

Yep! *SPECIAL* theory of Relativity.
Proven millions of times a day by many physicists the world around.
They get numbed by those facts.
However...
There is the theory of *GENERAL* relativity, where different frames
cannot be time-wise or speed-wise related ot each other. Case in point:
get a rocket starting from Earth, constantly accelerating away at some
value A, and at some point, its reference frame becomes inaccessible
from ours. No laws violated; just not practical to carry enough fuel to
accelerate so long that the velocity (before becoming inaccessible) gets
even near C.
An observer in that theoretical rocket would experience what all
physicists see: that the exhaust cannot get near C without using
gigantic amounts of energy.
But that has nothing to do with what an observer on Earth can measure
about the rocket itself, or what the passenger in the ship can measure
about the Earth.
By definition, the thought experiment sez that the velocity continues
to increase - and at some point the frames of reference disconnect.
Methinks the expanding universe can show us that limit, if we look.
What is it? the velocity of light. Gosh; how exact the *SPECIAL*
theory of relativity is!
 
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