# Freezing light

1. Dec 10, 2003

### Greg Bernhardt

2. Dec 11, 2003

### jimmy p

ok, so thats odd.. any suggestions on how they did it?

3. Dec 11, 2003

All of this data is off the top of my head, I claim no precision in any way. The experiment created atmospheric vacuum on the order of $$10^{-14} atmospheres$$ with temp on the order of $$10^{-3}$$degrees Kelvin. In other words at the time of the experiment the area created was the coldest and most vacuous place in the known universe. Again if memory serves me correctly - the paper came across my desk at my office, I am away for the holidays - a laser source(possibly sodium?) injected the light, and which became trapped in the area emitting a reddish-orange colour appearing wafer-like. If enough interest is expressed I would ring up back to my office and provide more specifics.

Edited the LaTex to correct exponents.
Integral

Last edited by a moderator: Dec 11, 2003
4. Dec 11, 2003

### HallsofIvy

Staff Emeritus
How does one DEFINE "temperature" in a vacuum?

5. Dec 11, 2003

[thanks for latex editing, infra]

Temperature ( perhaps we might need to just stick to numbers here, not "word definitions" as such since they cause this sort of confusion) is a function of the (integral) sum of kinetic energy; and since there is no absolute zero nor total vacuum, merely the ability to remove increasingly smaller volumes totals of the energy of a closed system/carnot which requires increasingly larger portions of energy. Classical mechanics can describe this well.

Expression in terms of percentage of Kelvin etc is appropriate much the same as velocity is expressible in terms of c, e.g., 0.89 c $$= {[ 0.89]} {[2.997 x 10^8 m /sec]}$$.

Last edited: Dec 11, 2003
6. Dec 11, 2003

### jimmy p

OK, so they injected light into a vaccuum and it was frozen for a split second. Does light follow Heisenbergs uncertainty principle? i know it would be easy to detect cos you can see it, but how would they know it had stopped?

7. Dec 11, 2003

ultra slow light

http://xxx.lanl.gov/PS_cache/cond-mat/pdf/0307/0307402.pdf

http://xxx.lanl.gov/PS_cache/quant-ph/pdf/9904/9904031.pdf

I just created the second pdf there, it should be ready for reading now. The mentioned group's research results are on that web site. The light is reported on the order of $$10^2m/sec$$, with other reports of slowing given in terms of c (as I indicated in this thread above)in recent experiments. This should answer the questions.

Heisenberg <=> quantum is concerned with one "end" if you will of the "universe"(<=>multiverse) and relativity with the "other end" although of course there is no rigour in this shorthand. Our goal as mankind has been said to understand how those ends meet.

As we progress technically (and Ed Teller [if not Michio Kaku q.v.] might have objected to the use of the word progress in this context)we see more new forms of matter arising (second article q.v.); similarly we see matter existing as "clumps" of nuclear particles, not matter existing as "atoms" (much less molecules) with other (atomic) particles stripped away as we are able to alter the conditions of matter in the laboratory for example approaching fusion temps (as at the centre of the sun) or in a neutron star.

8. Dec 11, 2003

The title of the article was slightly misleading. While the pulses were considered frozen, the photons were not. They were trapped, slowed and reflecting back and forth, within a small zone. They have slowed light, but not stopped it (including the photons) w/o the loss of photons (as in their energy was absorbed by the sodium or rubidium atoms, then reemitted later).

9. Dec 12, 2003

### jimmy p

OHHHH I see now! That makes a little more sense and stops my brain hurting!

10. Dec 12, 2003

### hey.like

solid surface T

The T is right in some solid surface.