Things faster than light ... (Is there a physicist in the house?)

Abdul Alhazred

Philosopher
A
Joined
Sep 4, 2003
Messages
6,023
Things faster than light, but they aren't really "things". :eek:

Faster-Than-Light Polarization Currents
Space Daily

Pulsars are neutron stars that emit amazingly regular, short bursts of radio waves, so regular that they were originally thought to be signals from little green men! Though their discovery over 40 years ago was very widely reported and resulted in a Nobel Prize, the reasons how and why they send these bursts has remained a mystery; to quote Jean Eilek of NRAO, "we know why they pulse, but why do they shine?"

However, in papers presented this week to the American Astronomical Society, Andrea Schmidt and John Singleton of Los Alamos National Laboratory provide detailed analyses of several pieces of observational data that suggest that pulsars emit the electromagnetic equivalent of the well-known "sonic boom" from accelerating supersonic aircraft. Just as the "boom" can be very loud a long way from the aircraft, the analogous signals from the pulsar remain intense over very long distances.

Schmidt and Singleton's presentations provide strong support for a pulsar emission mechanism (the superluminal model) due to circulating polarization currents that travel faster than the speed of light. These superluminal polarization currents are disturbances in the pulsar's plasma atmosphere in which oppositely-charged particles are displaced by small amounts in opposite directions; they are induced by the neutron star's rotating magnetic field.

Despite the large speed of the polarization current itself, the small displacements of the charged particles that make it up means that their velocities remain slower than light, so that Einstein's theory of Special Relativity is not violated. No laws of physics are broken in this model!

...
Click to expand...

I'm not quite getting what it is. Can someone please explain?

Thanks.
 
I'm not sure what this particular phenomena is but the appearance of superluminal movement is fairly easy to obtain. It just means that multiple locations separated by large distances are being coordinated from some other point.

A hypothetical example (please excuse the Biblical definition of pi applied here):

Let's say Earth is at the center of a 10 light year radius circle that is 60 light years in circumference. Along that 60 year circumference there are 60 planets. We number each of those planets and tell them what their number is. We on Earth send them a signal which they all receive at the same time. In that signal we tell them to turn on their beacons for one minute x minutes after they get the signal, where "x" is their planet number. And we tell them to continue doing that each hour from then on, sending a one minute signal out every hour.

A distant observer, who doesn't know about our signal, will see a phenomena that is moving at 60 light years per hour, many times faster than light speed. Each planet turns it's beacon on for a minute and turns it off, and then immediately, a light year away, another beacon comes on. And this proceeds around the 60 light year circle in an hour. So those distant observers are seeing a 60 light year long ring that has a pulse of light moving around it in an hour. It appears to be a phenomena moving much faster than light. But nothing that makes up this coordinated system is moving faster than light.
 
Last edited:
It's because of what current is.

What current is
Imagine this is a "wire". The asterisks are free electrons. Now this is happening on the wire:

Time 1:
Code: 
  123456789abc
1:*** * ** ***
The electron at position 7 moves to position 6. This results in:

Time 2:
Code: 
  123456789abc
2:*** ** * ***
The electron at position 5 moves to position 4. In addition, the electron at position a moves to position 9. This results in:

Time 3:
Code: 
  123456789abc
3:**** * ** **

Now, current doesn't quite work that way. Current is an alternate description--instead of describing the electrons, we describe the holes. So:

At time 1: The hole at position 6 moves to position 7, leading to...
Time 2: The hole at position 4 moves to position 5, and the hole at position 9 moves to position a, leading to...
Time 3.

And now I'm describing current. Current flows in the opposite direction as the electrons, and corresponds to the holes in the electrons, not the actual electrons themselves.

Current faster than c
Now given this language:
Time 1:
Code: 
  123456789abc
1:** ***** ***
Time 2:
Code: 
  123456789abc
1:**** ***** *

From time 1 to time 2, an electron moved from 4 to 3, and an electron moved from 5 to 4. Also, an electron moved from a to 9, and an electron moved from b to a. So the speed of these electrons is one unit of distance over one unit of time.

But...

Here, we have a hole moving from 3 to 5, and we have another hole moving from 9 to b. So the current moves at two units of distance over one unit of time. But the current is "holes", not matter. So the current could flow like this faster than c. This sounds like what is being proposed, though I haven't read up past the article.

ETA: Oh, by the way... I'm not a physicist.
 
Last edited:
yairhol said:
Cerenkov radiation is faster than the speed of light as well:
http://en.wikipedia.org/wiki/Cherenkov_radiation
Click to expand...

That's different, at least, from what's described in the article:
Thus far, polarization currents traveling at up to six times the speed of light (i.e. 1.8 million km per second) have been demonstrated to emit tightly-focused bursts of radiation by the ground-based experiments.
--Space Daily​
Here, by "speed of light", they are talking about c.
Cherenkov radiation (also spelled Cerenkov or Čerenkov) is electromagnetic radiation emitted when a charged particle (such as an electron) passes through an insulator at a constant speed greater than the speed of light in that medium.
--wikipedia​
...and here they're just talking about the speed of light slowed down by a medium. But this sort of thing was what I was thinking at first as well.
 
Tubbythin said:
[pedant]Cerenkov radiation doesn't travel faster than light, it is light. It is caused by charged particles traveling faster than light in that medium.[/pedant]
Click to expand...

yeah, Cerenkov radiation is the luminal equivalent of a sonic boom, which is the audio equivalent of a bow wave.
 
yy2bggggs said:
It's because of what current is.

Here, we have a hole moving from 3 to 5, and we have another hole moving from 9 to b. So the current moves at two units of distance over one unit of time. But the current is "holes", not matter. So the current could flow like this faster than c. This sounds like what is being proposed, though I haven't read up past the article.

ETA: Oh, by the way... I'm not a physicist.
Click to expand...

Your description is misleading. current is the movement of charged particles. In the case of wires, these are electrons. You can also think of the gaps (holes), but that doesn't change what current is.

What is important are the phase and group velocities. If I push an electron in one end of a wire, almost instantaneously an electron will pop out of the other end. Although no single electron has moved in the wire very much. The group velocity is the (very slow) speed of the electrons. The phase velocity is the (very fast) speed of the signal popping out the other end.

In regular wires, the phase velocity is close to the speed of light, but the group velocity is less than 1mm/s.

Think about water waves. The wave travels across the surface but the individual water molecules hardly move.
 
nathan said:
What is important are the phase and group velocities. If I push an electron in one end of a wire, almost instantaneously an electron will pop out of the other end. Although no single electron has moved in the wire very much. The group velocity is the (very slow) speed of the electrons. The phase velocity is the (very fast) speed of the signal popping out the other end.
Click to expand...

AIUI this is also true of Cherenkov Radiation - it exceeds the phase velocity of light in the medium, not the group velocity.
 
The article says the current is caused by the stars rotating magnetic field. I don't know how a neutron stars magnetic field arises but I do know that magnetic fields, not being material bodies, can rotate at any speed. In fact for every rotating magnetic body there is some point where the field has to be moving faster than light.

For example for Earth: Earth rotates once per day, a light day is about 2.5 x 1013 meters. So for any distance from Earth where a circle drawn around Earth is that long, then anything outside that point sees Earth's magnetic field rotating faster than light. They wouldn't notice this if Earth's field is rock solid steady, but if there were some variation in Earth's field this disturbance would propagate tangentially across them at faster than light. The disturbance would propagate towards them at light speed, but it would propagate across the tangent of the circle faster than light. It's the disturbance that propagates at greater than light speed, not the components of the field.
 
Last edited:
RecoveringYuppy said:
The article says the current is caused by the stars rotating magnetic field. I don't know how a neutron stars magnetic field arises but I do know that magnetic fields, not being material bodies, can rotate at any speed. In fact for every rotating magnetic body there is some point where the field has to be moving faster than light.

For example for Earth: Earth rotates once per day, a light day is about 2.5 x 1013 meters. So for any distance from Earth where a circle drawn around Earth is that long, then anything outside that point sees Earth's magnetic field rotating faster than light. They wouldn't notice this if Earth's field is rock solid steady, but if there were some variation in Earth's field this disturbance would propagate tangentially across them at faster than light. The disturbance would propagate towards them at light speed, but it would propagate across the tangent of the circle faster than light. It's the disturbance that propagates at greater than light speed, not the components of the field.
Click to expand...

Not sure if this is strictly true, as EM fields propagate at the speed of light. So you would get a funky spiral.
 
ponderingturtle said:
Not sure if this is strictly true, as EM fields propagate at the speed of light. So you would get a funky spiral.
Click to expand...
Right, except you're explaining why it is true, not why it's not. The propagation of a tangential disturbance in a magnetic field would propagate outward as a spiral. That spiral would intersect any circle and the point of intersection would proceed around the circle at a speed proportional to the radius of the circle and the speed of light would be no restriction to that point of intersection since that point of intersection is not a material object.
 
Last edited:
RecoveringYuppy said:
Right, except you're explaining why it is true, not why it's not. The propagation of a tangential disturbance in a magnetic field would propagate outward as a spiral. That spiral would intersect any circle and the point of intersection would proceed around the circle at a speed proportional to the radius of the circle and the speed of light would be no restriction to that point of intersection since that point of intersection is not a material object.
Click to expand...

The thing is that you are dealing with something that is moving at C and claiming it is resulting in something that is moving at greater than C. Nothing is moving at greater than C. It is just a mathmatical artifact. I mean you want a real extreme example, look at a pulsar, the pulse of light might be at say 20 hertz and if it is 1000 parsecs away you would say that the light is moving both at C and ar more than a million times C.

But nothing is actualy moving and certainly not carrying information at anything but C.
 
I'm not saying any information or material is moving at greater than c. I'm saying that something moving at c can coordinate other things to give the appearance of a phenomenom moving at greater than c. The point of intersection between the expanding spiral and the circle that we just discussed is not a material object (in fact I notice I'm repeating myself and something you quoted. Did you miss the word "not"?)

How are you saying your pulsar example leads to the appearance of greater than c?
 
RecoveringYuppy said:
I'm not saying any information or material is moving at greater than c. I'm saying that something moving at c can coordinate other things to give the appearance of a phenomenom moving at greater than c. The point of intersection between the expanding spiral and the circle that we just discussed is not a material object (in fact I notice I'm repeating myself and something you quoted. Did you miss the word "not"?)

How are you saying your pulsar example leads to the appearance of greater than c?
Click to expand...

Sure, look at how fast the beam is sweaping an entire arc. It is sweeping an arc with a radius of 1000 parsecs 20 times a second. This is an exact analog to what you are saying.
 
Oh, I didn't know you meant it was sweeping. In that case, it's not just an analog to what I'm describing, it's an example. Something that gives the appearance of faster than c but is merely distant activitity being triggered from another location.
 
RecoveringYuppy said:
Oh, I didn't know you meant it was sweeping. In that case, it's not just an analog to what I'm describing, it's an example. Something that gives the appearance of faster than c but is merely distant activitity being triggered from another location.
Click to expand...

A pulsar by definition sweeps. It only appears to pulse because we can only see it sweeping on a very small area.
 
Yes, I know. But I thought you were saying we'd infer a high velocity from the facts you mentioned (which were be from our POV here on Earth). Yes, if you observe the pulse sweeping across distant objects (and those objects don't necessarily have to be at our distance, that's just one example) you'd see the appearance of very high velocity.

Are we just miscommunicating or do you really think there is something wrong in posts 2 and 12?
 
You must log in or register to reply here.

Back
Top Bottom