# Is it possible to create light?

1. Nov 17, 2015

Is it possible to create light with electric field and magnetic field since light is a type of electromagnetic radiation?

P.S. With laser cooling you can slow down light to 38MPH.

2. Nov 17, 2015

### TeethWhitener

Yes it is. In fact, you might have posted the message above by creating light. All you need is an antenna and a radio transmitter (both commonly used in your cell phone's Wi-fi communication): https://en.wikipedia.org/wiki/Antenna_(radio)

If you mean visible light, we don't yet (as far as I'm aware) have a good way of directly generating oscillating electric fields at that frequency.

3. Nov 17, 2015

### DrStupid

4. Nov 17, 2015

### TeethWhitener

5. Nov 17, 2015

### Staff: Mentor

6. Nov 17, 2015

### DrStupid

Last edited by a moderator: May 7, 2017
7. Nov 17, 2015

### Staff: Mentor

Last edited by a moderator: May 7, 2017
8. Nov 17, 2015

### DrStupid

0,00005 %

9. Nov 17, 2015

### Staff: Mentor

Ouch! Okay, you just saved me \$36...

10. Nov 19, 2015

I was thinking by passing light through electric field or magnetic field the wavelength might change, since they are made from these two components, but I can't seem to find any source on it on Google. Now that we've slowed down light to 38mph, is there a change in relativity sense of light? I've heard that someone mentioned this concept can be used for data storage but I haven't really looked into it.

11. Nov 19, 2015

### phinds

Nothing has changed about the properties of light. It still travels at c in a vacuum and at lower speeds in other materials.

12. Nov 19, 2015

How about this formula? Just speculating, well I thought it is interesting to put 38^2 in the formula.

13. Nov 19, 2015

### Staff: Mentor

You should not think of "c" in most relativity-related formulas fundamentally as the "speed of light (in a vacuum)", but rather as the "universal speed limit" or "universal invariant speed". Light happens to travel at that speed because it's associated with massless particles. Other massless particles also travel at that speed. If photons had mass, light (in a vacuum) wouldn't travel at speed c.

14. Nov 19, 2015

### Staff: Mentor

Interesting but meaningless, as the $c$ in that equation is the speed of light in vacuum, not a medium.

However, it's mostly for historical reasons that we say "$c$ is the speed of light". $c$ is a constant of nature in its own right, and if it ever turned out that light in a vacuum did not move at $c$ (which is not going to happen) we wouldn't say that we were wrong about the value of $c$, we'd say that we wrong about the behavior of light.

Last edited: Nov 19, 2015
15. Nov 20, 2015

How about this one? If I am a photon (it doesn't need to be in a vacuum right?) I would see that any distance I want to travel to is close to zero (if I remember what was taught in high school Physics). Then suddenly I am slowed down to 38mph and an entire universe appeared. Now this doesn't mean you need to be in an Einstein-Bose condensate to feel this? Then again why do I need to create more distance for myself by putting myself inside an Einstein-Bose condensate.

16. Nov 20, 2015

### phinds

There is no such thing as the frame of reference of a photon so your question is not meaningful.

17. Nov 20, 2015

Well, there is a frame of reference for an object close to the speed of light right? Is having a mass a requirement?

Credit:

18. Nov 20, 2015

### ZapperZ

Staff Emeritus
There is a series of severe misunderstanding here that should have been corrected.

First of all, one needs to clearly understand what is meant by "the speed of light" that the OP is referring to, and this is especially the case when we are talking about the speed of light in a medium. This is the group velocity of light! That is what being slowed down in a medium.

Secondly, light has been slowed down, but has been slowed down to ZERO m/s. This means that it has been stopped, held for some time, and then "replayed" back (this is different than light being absorbed completely by an opaque object).

Thirdly, an antenna generating EM radiation is the same as having a bunch of charge, such as a bunch of electrons, being jiggle up and down (or left and right, etc.). This is similar to what is being done in the numerous synchrotron light sources all over the world, and in the many FEL facilities around the world. Most of the light being generated (including, in principle, visible, UV, IR, etc.) are bunches of electrons passing through an insertion device such as a wiggler or undulator that causes the passing bunches to jiggle back and forth, just like what you do in an antenna due to the moving current.

Zz.

19. Nov 20, 2015

### phinds

Yes there is. What does that have to do with the current discussion???

A requirement for what? Having a frame of reference? Then, yes, in that massless objects travel at c and have no frame of reference.

20. Nov 20, 2015

Well, here's a discussion about Photon's frame of reference. So I suppose I'll just leave it at laser cooling, sorry about that. How about anything at high temperature? Anyone got a video on that?

21. Nov 20, 2015

### ZapperZ

Staff Emeritus
That discussion simply re-enforced the idea that such a reference frame doesn't exist in Relativity (look at the postulates of Special Relativity). You need to understand that first and foremost before attempting to use anything from Relativity. Otherwise, you'll be using it in places where it wasn't meant to be used.

Zz.

22. Nov 20, 2015

Well yes, that's why I left my idea at laser cooling and laser cooling is done before. And now I want some information about atom at super high temperature.

23. Nov 20, 2015

### ZapperZ

Staff Emeritus
That's super vague. Atoms at "super high temperatures" are no longer atoms. They could be a plasma!

Zz.

24. Nov 20, 2015