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the Speed of Light
- Thread starter Thief
- Start date
BSM1
What? Me worry?
School Zone maybe?
Buddha Dharma
Dharma Practitioner
No I haven't. Isn't light sometimes thought to be beyond time, since time arguably requires mass?
Thief
Rogue Theologian
no ....for real
I don't recall the entire process....
something about freezing a material to a limit not known in the natural world
and then sorting through the stuff for the coldest portions
then shine a light through it
light slows to 15mph
upon exiting it regains it's natural speed
The scientist was interviewed in the program
she seemed very confident in her work
I don't recall the entire process....
something about freezing a material to a limit not known in the natural world
and then sorting through the stuff for the coldest portions
then shine a light through it
light slows to 15mph
upon exiting it regains it's natural speed
The scientist was interviewed in the program
she seemed very confident in her work
Thief
Rogue Theologian
time is a measure of movement
it is not a substance or a force
Speed of light in vacuum is a constant. Not so through materials.
Actually, light has been slowed to very slow speeds, and to a standstill on a number of occasions over the last decade or two. I'd have to hunt that up, though.
Buddha Dharma
Dharma Practitioner
Please do, if you don't mind
Heading for bed right now...I'll try to remember in the AM
Buddha Dharma
Dharma Practitioner
If you don't- don't worry about it. It's not important.
I like the term "optical molasses" in this article, which briefly explains how light can be slowed down and possible future uses for the technique:
Physicists Slow Speed of Light
Physicists Slow Speed of Light
I believe it’s possible. The brake lights on the old lady’s car in front of me were going about 15 mph.
Subduction Zone
Veteran Member
It probably involved the use of a Bose-Einstein condensate:
Bose–Einstein condensate - Wikipedia
In fact this may be the article that the OP was talking about:
Harvard Physicist Plays Magician With the Speed of Light
Bose–Einstein condensate - Wikipedia
In fact this may be the article that the OP was talking about:
Harvard Physicist Plays Magician With the Speed of Light
Skwim
Veteran Member
Err. . . that news is a bit old. Ten years old.
About a decade ago, [Harvard Physicist Lene Vestergaard Hau] started playing with BECs — for a physicist, that means shooting lasers at them. She blew up a few. Eventually, she found that lasers of the right wavelengths could tune the optical properties of a BEC, giving Hau an almost supernatural command over any other light shined into it. Her first trick was slowing a pulse of light to a crawl — 15 mph as it traveled through the BEC. Since then, Hau has completely frozen a pulse and then released it.
source
Note that she was able to "freeze" light and release it.source
.
sandy whitelinger
Veteran Member
It's a relative thing.
First of all, the speed of light *in a vacuum* is what is constant.
Light does, however, slow down when is passes through matter. For example, when it goes through water, it slows to 75% of its vacuum speed. When it goes through glass, it slows to about 65% of its vacuum speed (depending on the type of glass).
Slowing to *very* slow speeds is also possible, but trickier. The main thing is that the matter is reacting to the light as it goes through and the degree of interaction is enough to slow the light to quite low speeds.
It has been actually possible to *stop* light entirely and 'restart' it.
More information to be found here:
Slow light - Wikipedia
Light does, however, slow down when is passes through matter. For example, when it goes through water, it slows to 75% of its vacuum speed. When it goes through glass, it slows to about 65% of its vacuum speed (depending on the type of glass).
Slowing to *very* slow speeds is also possible, but trickier. The main thing is that the matter is reacting to the light as it goes through and the degree of interaction is enough to slow the light to quite low speeds.
It has been actually possible to *stop* light entirely and 'restart' it.
More information to be found here:
Slow light - Wikipedia
Thief
Rogue Theologian
it seems this news to me is not so new.....
somebody.....Hau.....did this trick ten years ago
heat sodium to 350.....and form a cloud
super cool the sodium using lasers (not sure how that is done)
and the cloud is colder than anything found in nature
then shine a light through it
the beam slows to speeds we are familiar to
and when the light leaves the cloud it goes back to it's know constant
it was news to me
somebody.....Hau.....did this trick ten years ago
heat sodium to 350.....and form a cloud
super cool the sodium using lasers (not sure how that is done)
and the cloud is colder than anything found in nature
then shine a light through it
the beam slows to speeds we are familiar to
and when the light leaves the cloud it goes back to it's know constant
it was news to me
Kangaroo Feathers
Yea, it is written in the Book of Cyril...
C is only the speed of light in a vacuum. It's speed varies through different media.