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IBM Slows the Speed of Light
dptalia writes "According to an article on ZDNet, IBM has come up with a way to slow light to 1/300 of its normal speed. While this has been done in laboratories before, IBM has found out how to do this using standard materials, which opens the possibility of mass production. This means that the dream of having optical based CPUs may be closer than previously thought." From the article: "When the optical conversion might start to occur is a matter of speculation. Luxtera has said it will start to commercially produce products in 2007. The computer industry, however, tends to move slowly when it comes to major overhauls of computer architecture. Several components will have to be developed before photons can replace electrons inside computers. A paper providing details on the chip will run in Nature on Wednesday."
Joke aside, it's always been a variable. It changes depending on the medium it's traveling through. 'c' is just the speed of light in a vacuum.
but yes, there's a link. Your full-text access may vary.
Don't blame me; I'm never given mod points.
It allows you to build chips using light, at speeds for which we can reasonably design things, and interface them with things at small fractions of C. The benefit to the optical chip is power and heat, which means you can pack more chips in, which means you can make a faster computer.
I want to delete my account but Slashdot doesn't allow it.
Every Pratchett fan knows that light slows down if you apply a strong Magical field...
Light thinks it travels faster than anything but it's wrong. No matter how fast light travels it finds the darkness has always got there first, and is waiting for it.
- Reaper Man
I guess this is one way to achieve faster than light travel.
I know you're joking but just in case anyone doesn't understand, you can't actually slow light down. When light passes through a medium, glass for example, the atoms in the glass absorb the light and then re-emit it. So, an atom on the outside edge of the pane of glass absorbs a photon and then reemits it, then the next atom in the glas absorbs it, and so on until the light emerges from the inside edge of the glass. The total trip time for light was greater than c/distance, but no actual photon was ever slowed. It's like when a packet goes through a router. On the other side of the router, you get electrons - just not the same electrons.
http://science.slashdot.org/article.pl?sid=05/08/2 0/1440228&from=rss
There you go.
The higher the dispersion, the lower the practical bandwidth of the device.
Two wrongs don't make a right, but three lefts do.
The latest Nature podcast has an interview with one of the researchers working on this: http://www.nature.com/nature/podcast/index.html
Step 1: Pass light through any medium which is not a complete vacuum.
That's it!
Yes, and all this is usually summarized by the notion "speed of light in medium".
>> I'm waiting for the day when we can raise the speed of light so we can go faster.
> I'm not sure this technology can be pushed in that direction
Let us hope that the speed of light cannot be changed as it is vital to the operation of the universe as we know it. For example, the fine structure constant of the universe (alpha) depends on the speed of light, and if the f-s contstant changes since c changes then funny things could happen, like electron having too much energy to orbit an atom, or fusion no longer occuring in stars.
There is also talk about the speed of light changing in the past, being faster than today and it could be slowly slowing down. If this were true then life might no longer exist in the far future given the effects of the changes in constants that depend on c. The link is an article from Scientific American about the possibility that physical constants (like light) aren't constant after all.
There are multiple uses for a slowed signal; you can combine it with the un-delayed
signal and make filters, like is done with SAW filters (but those use surface acoustic waves,
and are not silicon-compatible). You can also make some kinds of shift register
VERY simply by sending the signal out into the delay and picking it up when you
need it. And a delay of a clock signal often makes a computer more reliable (designing
high speed compute devices, this is OFTEN a vital consideration).
The split/multiple delay/combine scheme for (for instance) radio signals is
a very powerful tool, and is why a complicated-looking antenna can work
so well. And, why a rabbit-ear antenna can take a lot of tweaking to
get your idiotbox to receive Red Green.
For major processing of data, it was common practice in the old days to tweak the
interconnect wiring to make the correct time delay. Seymour Cray reported (of the
Cray-1 supercomputer) that the interconnect in the central core of the computer
was hand-wired by (slender women) assemblers who used cut-to-measure lengths of
twisted pair, so that all the signals had the appropriate settling time before the clock
arrived and latched the data. The computer was a cylindrical hole with draped wiring
all over its interior, with spokes out that housed the cooled ECL logic modules.
To keep the Cray quick, the cylindrical core was as small as feasible. The assemblers
knew a LOT of the common computer language of their profession, i.e. profanity.
I wrote an article for today's Wired News on IBM's discovery (along with another recent photonics discovery from Stanford) and asked a number of scientists whether this "slow light" chip might have applications for quantum computing. The sense I got was that, generally, slow light may indeed come in handy for a photon-based quantum computing system. But since it's a room-temperature, silicon-based chip (read: LOTS of quantum noise), it doesn't seem likely that this particular slow light environment would be qubit-friendly.
If this can be done using "standard materials", as the article mentions, one wonders if our calculated estimates of distance to stars could be off, considering all the unknowns outside the solar system.
Generally, the speed of light is used only for "close" objects. For objects outside of the solar system, other properties are used including parallax, spectral type, and luminosity. None of these properties depend on the speed of light. Here is an informative link on methods used at various distance scales.
You are not thinking this through. If light slows down, then you will be able to "see" into the past. So when the mom walks in, she will be able to "see" what happened a moment ago.
It is not that light is "really" made out of some particles called "photons", you can look at it as a wave phenomenon as well. Neither Newton nor Huygens were right about the nature of light. Just reducing light to a bunch of particles is a simplification. It's not, that your explanation is wrong, one is just not forced to choose the particle picture. And if you look at it as a wave and measure its group velocity, you can call it the speed of light. If you are in a situation where you could be misunderstood, you may add "in (a specific) medium". What is constant is the speed of light in vacuum.
Apparently, the speed of light when the zero point energy is lower (as between the two plates generating the Casimir effect) the speed of light is higher than the speed of light in vacuum at normal zero point energy levels.
a rpstat.html
http://www.nasa.gov/centers/glenn/research/warp/w
I like my dinosaurs feathery, and my pterosaurs hairy (or is it pycnofibery?)