news.mit.edu
archive.is
So I'm really confused now about the properties of light quanta now. I remember we just had a thread here about photon mass and everyone agreed the mass of a photon was it's energy. So what's happening here? Is the ultra-cold gas converting energy to mass?
Also is this "new form of light" even still considered a photon, at slow speeds and with mass wouldn't it be better described as a type of lepton now.
>In controlled experiments, the researchers found that when they shone a very weak laser beam through a dense cloud of ultracold rubidium atoms, rather than exiting the cloud as single, randomly spaced photons, the photons bound together in pairs or triplets, suggesting some kind of interaction — in this case, attraction — taking place among them.
>While photons normally have no mass and travel at 300,000 kilometers per second (the speed of light), the researchers found that the bound photons actually acquired a fraction of an electron’s mass. These newly weighed-down light particles were also relatively sluggish, traveling about 100,000 times slower than normal noninteracting photons.
that's probaby an effective mass
effective mass is not actually mass
3km/s != photon
So what is it?
they describe it as acquired mass, so was it actually effectively acquired mass?
that's only the speed of photons in free space. you can slow them down inside stuff
If they're coupling and stimulating emission of other same-energy quanta isn't this better described as a laser-like effect in an exotic medium?
Every time a paper dresses up an oddity as novelty, I die a little.
>effective mass is not actually mass
>the researchers found that the bound photons actually acquired a fraction of an electron’s mass.
Nope, they even said actually. So that's clearly labeled actual mass being acquired, a fraction of the mass of an electron, not specific but I assume 1/9th.
idk, but effective mass is something that smears a bunch of complicated stuff together into term that acts like mass
I think it's [math]\mathbb{R}[/math] unlikely that the photon acquired mass.
Massive photons would have three polarizations and that would mess up the EM field
Yes, then they come out and go back to c...
Not stay in pairs with measurable mass.
Interesting, massive photons break all sorts of rules. I'm guessing this is some bullshit from the universities PR department. So I found the paper and they only talk about an "effective mass". So I don't think that it's a "real" (ie physical) mass.
>effective mass is not actually mass
photons already have "relativistic mass" which is a completely obsolete concept in the first place, so that's obviously not what they're referring to here in any sense. also that wouldn't even make sense in this case. these photons acquire mass and then logically slow down because anything with mass cannot travel at c
First i just learned that there is a difference between the theoretical mass (=0) and the experimental mass (< 10^−54 kg).
Second : If photons have mass and can go 0.0001c, can we still call it a photon ?
I found the answer.
>This research was supported in part by the National Science Foundation.
haven't read the paper but if this is the case, don't go to that uni lmao
i saw this shit on reddit and ignored it to continue looking for porn and im glad i did
effective mass is an irrelevant concept at this point
Death to the "x,0000 time slower meme. It's sloppy thinking that encourages more sloppy thinking and misunderstanding, since "slowness" is no the measured attribute.
If the slowness of bound photons my be said to go some fractionally stated number of the speed of the unbound ones, or the speed of the bound ones can be X distance/interval slower.
You can almost get away with it when talking photons, where there is an upper speed set by C and presumably the lowest possible speed of 0. But even there you're going to make problems. A slowed photon that goes.9 c is compared to another that goes .45 c -- is it going 40% slower? 450$ slower? Something else? Who the fuck knows, "slowness" is not an attribute..
This sort of sloppy thinking leads to statements like "it was twice as cold as it was yesterday. The fuck doe that even mean? It'a a meaningless statement that only informs the listener that it is, to some degree, colder that yesterday.
Can you post a link for the paper, or a DOI number, I can't find anything.
>“For example, you can combine oxygen molecules to form O2 and O3 (ozone), but not O4, and for some molecules you can’t form even a three-particle molecule,” Vuletic says. “So it was an open question: Can you add more photons to a molecule to make bigger and bigger things?”
This guy is just fishing for funding and publicity with the pop-sci crowd.
We already have spectroscopic methods reliant on multi-photon/vibrational coupling. See raman spectroscopy.
>theoretical mass (=0) and the experimental mass (< 10^−54 kg)
you're referring to rest mass and relativistic mass. ignore relativistic mass and don't think about it ever again physics.stackexchange.com
does Veeky Forums not sci-hub?