Trance

Is this possible? Scientists claim they can do it now. What I can't comprehend how can you stop something that has no mass (photons)! From what i read, i understand that they're not really stopping it, but rather slowing it down and finally storing the information of wavelenght, intensity etc (all the descriptive quantities of it) and releasing that information from the suspended atoms where it was stored, effectively re-creating it, not really stopping . Is that correct?

Harvard Gazette: Researchers now able to stop, restart light
News in Science - Stopping light in its tracks - 03/04/2002
Scientists Stop Light in 'Trapped Rainbow' | LiveScience
Stop Light on a Chip | Physical Review Focus

fromaron

Nice find Trance. Interesting reading.
Actually Einstein was right by saying E=mc^2 .
The higher energy the higher speed is. By introducing ultra cold chamber (heat is an energy as well) scientist have created place for a very fast energy exchange. Cooled down atoms would accept energy from the light beam, so light will loose it's energy. As result the light should travel slower (see Einstein's formula).
This is my understanding only, which is really contradicts to the electrical superconductivity achieved in ultra cold chambers. Ultra conductivity actually suppose to increase electron's speed through a conductor due to resistance reduction.

mickc

nothing new
have been doing it for years befor i go to bed

trash

Yes, they've been doing it for quite some time.
The bose-einstein condensate (a fancy name for a superconductor) is used.
In the example that I know of a super cooled gas is used. Sodium atoms were cooled and when set up correctly it could stop photos completely for a period up to ~500mS.

osiris777

i know it sounds like something from a sci fi movie but i actually have a so called light stopping device, i call it 'the lightswitch'
did you stumble across one of these also Mick?

__________________
...In Somnis Veritas...

tytower

We'll have to share our recipie with Trash and osiris777.
Mix viagara with eye drops so you can have a long hard look at yourselves !

trash

It sounds like you've got a bad case of synesthesia Tytower.
It's probably caused by excessive neural pathways formed between the pudendal nerve and Occipital lobe in the brain.
It would explain your shitty outlook on life.

osiris777

what he said, times 2!

__________________
...In Somnis Veritas...

tytower

at least my mind is open to pursuasion and common sence reasoning not silly fantasy clowns

Onefella

That's nice. My mind is open to recorded scientific method, such as controlled experimentation coupled with unbiased, recorded observation and critical assessment by scientific peers.

"common sence [sic]" is highly subjective and in your case, often wrong.

bulbous

...you, Onefella, are not a bloke easily open to "pursuasion" (sic, again !)....but then again the arguments and attempted barbs of user tytower have no great éclat.

They are more comical than anything !

Onefella

heh, I still learned something from Trash even in a flame post.

Because I had to go away and google "pudendal nerve".

Artilect

As far as I understand physics, regardless of the temperature(vaccuos space is very close to absolute zero) light tavels at a fixed velocity known as c AKA the speed of light. The speed of light is a constant in a vaccume, but, through a medium it slows down, that is why glass can bend light.
The importance of the Bose-Einstien condensate is that it slows down light by a significant factor.
It's creation is another proof that the General Theory of Relativity is an accurate description of Physics.

As far as E=mc^2 that holds true for all energy exchanges including conventional combustion.

__________________
Sextus Empiricus advises that we should suspend judgment about virtually all beliefs, that is, we should neither affirm any belief as true nor deny any belief as false.

Pyrrho stated that "nothing is in itself true or false. It only appears so. In the same way, nothing is in itself good or evil. It is only opinion, custom, law, which makes it so."

trash

Not sur what relitivity has to do with conventional combustion. You may be confused with the laws of Thermodynamics which relate to the conservation of energy and which relativity is a part.

Artilect

Everything including Thermodynamics is goverened by Relativity, you must have missed that Lecture trash.

when a standard combustion reaction takes place say a piece of wood, the energy released will be equal to the matter lost multiplied by the speed of light squared.

Say after combusting a piece of wood you some how managed to capture all the Gasses released and Ashes, when you weigh it all up there will theoretically be a very small amount of matter missing, this can be calculated using Energy= Matter(Lost) x C^2. It is after all just physics...

__________________
Sextus Empiricus advises that we should suspend judgment about virtually all beliefs, that is, we should neither affirm any belief as true nor deny any belief as false.

Pyrrho stated that "nothing is in itself true or false. It only appears so. In the same way, nothing is in itself good or evil. It is only opinion, custom, law, which makes it so."

trash

I must have missed that lecture, because when you burn a piece of wood, you haven't lost any mass. The chemical energy is converted into eletromagnetic energy. There is not nuclear process involved, no exchange of mass for energy.

Lets simplify it to water. If you burn hydrogen and oxygen in a sealed container it weighs exactly the same as before and after the burn.
It's a chemical reaction, not a nuclear one. There is no missing mass.
The four (2xH2) hydrogen atoms weighed 1.00794 amus before the burn. The two oxygen molecules (1xO2) each weigh 15.9994 amu before and after the burn.

The two water molecules that are the result each consist of two hydrogen and one oxygen (2x H2O) for a grand total of 18.01528 amu.

Did I miss any mass ?

anyone

i thought if you burnt wood energy was created as in heat, thus losing mass.maybe im missing something. edit yup we got some light as well

Artilect

Actually you did, a minuscule amount of mass is missing and the resolution you are working with isn't accurate enough to show it (try another 20 decimal places), and it must equate to the amount of energy that has been released as heat. Don't believe me ask any Physicist. The reason you will not notice it is because the "speed of light squared" is such a huge number (90000000000000000) that you need combust fuel like a coal power station for 10 years before you are able to make a significant weight measurement.
Just do the math it works out, calculate for reactions that emmit Giga watts and divde by the speed of light squared and you will find that perhaps a measurable amount of matter is missing. The Energy transfer formulae holds true for all reactions including chemical ones. Chemical reactions are so weak that it can be overlooked because the number is so small, that is probably why it is better ascociated with nuclear reations. Because E is significant and the uranium rods will weigh less when they are spent. What I am saying is a matter of fact, if you understood relativity you would agree without the embarrasing argument.

__________________
Sextus Empiricus advises that we should suspend judgment about virtually all beliefs, that is, we should neither affirm any belief as true nor deny any belief as false.

Pyrrho stated that "nothing is in itself true or false. It only appears so. In the same way, nothing is in itself good or evil. It is only opinion, custom, law, which makes it so."

BillyGoat

All over my head.
But I am learning with these posts.

trash

Yes, I do agree. There is a missing mass.
It's not an embarssing argument at all.
From your first posts I wasnt sure that you understood what your were saying. We do get a bit of that from time to time here remember.

It's not quite the description I was hoping you'd give, but it's a fare enough explination of why I don't want to waste half an hour of preaching to the converted.

For Billygoat and others who are wondering what we are talking about.
Typically there is a difference between the weight of matter before and after a nuclear reaction. Uranium 235 is split into two lighter elements, and a couple of neutrons. When you weigh up all these "fission fragments" they weigh less than the original U235. The missing mass has been converted into energy. That mass is big enough for us to actually measure it.

But in Chemical reactions, all the atoms and electrons are still there before and after the reaction. They haven't changed their mass. So where did the energy come from ? Chemically, the various coumponds have chemical energy in their bonds. The number of electrons in their shells and how those electrons are arranged.

To put it in more newtonian terms .... an electron in a higher orbit moves faster. In relativity, the faster an object moves, the more mass it has. When it falls to a lower orbit, it looses speed (and mass) that is then emitted as energy, like a photon.
A car rolling down a hill aquires a tiny amount more mass the faster it moves by the same sort of logic.

Electrons in their various shells are a little more complex, and as Artilect said, these tiny differences are just too small to measure they are ignored in terms of relativity.
Joules per Mole or Kilogram is just easier to work with than a bucket of zeros.