We all know light has mass and that concentrated, light can become more solid (lasers). What I"m curious about is if light can be made to become “solid” in some way…as in able to be handled or manipulated in some way. I think Einstein said that as you approach the speed of light that it all becomes solid again? Sorry if I’m really off on that one… While I’m on lasers… can a laser be made to be strong as the most powerful kind (burn through metal etc.) and not be visible to the naked eye and possibly modern technology?
Light has zero (count it zero) rest mass. It can never be still… so there’s really no solid state allowed. You’re really mixing your terminology there.
No, a naked photon is something for the ages. It will either be absorbed or pass on by at the speed of light. No ifs ands or buts about it.
No, Einstein said no such thing.
In principle, you can make a laser out of any wavelength photon, so you could have one that was not visible to the naked eye… except you’d be able to see its effects. Modern technology can detect all photons since they couple so well with the matter we see around us every day.
Light always travels at c in vacuum, no matter how fast you are moving. So you can never hold a bar of light in your hand. However light slows down when travelling in other medium.
As for lasers, what do you mean by “not visible”? If you look at a laser beam from the side (i.e. the laser is not shining into your eyes) in vacuum, it isn’t visible. It becomes visible only when the beam goes through things that scatter light (dust, smoke).
If you mean lasers other than visible light, there are infrared and ultraviolet lasers, and even X-ray lasers. You wouldn’t see them even if the beam was directed at your eyes, though you may feel the heat or radiation burns.
What if you were to saturate the space time continuum with photons…one photon per cubic Planck length per Planck interval?
Would a laser beam of such intensity provide a measurable push against a potentiometer?
Bose-Einstein condensates could be thought of as “solidifying” light:
So you could shine a light into a BE condensate, then mail it off to your grandmother with instructions to pop it into the oven on christmas morning. Is that solid enough ?
Thank you guys so much for not treating me like an idiot, it was a risky question and I appreciate the research that went into answering what I couldn’t even begin to know enough to search for myself. Hat’s off to all of you.
Bose-Einstein condensate is NOT solid light.
BEC is regular matter that has been cooled down to within a Billionth of a degree of Absolute Zero, at which point( due to particle/wave duality and the Uncertainty principle) the individual atoms stop behaving like individual particles and behave more like a wave.
Enola, Squink wasn’t saying it WAS solid light, he is saying it could be thought of “solid light”. I can see how one would say this… I put a light beam in Bose-Einstein condensate and it rattles around in there for much longer than I’d expect… being absorbed and reemitted and generally slowed down. It’s “solid” not in the physical sense of the world, but some metaphysician might say that it is somewhat solid.
However, some metaphysician might also say putting water in a glass makes the water “solid” since it is contained within the glass. Or air in a balloon. Yeah, metaphysicians can get kooky. That’s why we stick to physics and say with authority that there is no such thing as “solidifying” light.
Light has momentum. It may not have mass but it has momentum. It can push all it wants to on things (ala photoelectric effect).
Furthermore, the universe, to some extent, IS saturated with photons they are from the Cosmic Microwave Background. Also, since photons can easily occupy the same states (you can have more than one photon in the same “space”), I’m not quite sure what you are driving at here.
Thanks JSP, that’s exactly what I was trying to get at. The question was asked by a non-physicist, so to answer it satisfactorily we have to consider what a non-physicist might take as the definition of being “solid in some way”.
Can I ask a supplementary question? I understood momentum = mass x velocity. So if light has zero mass, how can it have momentum, since 0 times anything = 0 ?
That’s an approximation, good when the speeds involved are much less than c (which is almost always, in day-to-day life). Of course, though, when you’re dealing with light, that approximation is blown right out of the water.
One expression for momentum that is valid for high speeds is E[sup]2[/sup] = p[sup]2[/sup]c[sup]2[/sup] + m[sup]2[/sup]4[sup]2[/sup], or p = sqrt(E[sup]2[/sup]/c[sup]2[/sup] - m[sup]2[/sup]c[sup]2[/sup]). If we plug in m=0 for a photon, we find that a photon has momentum equal to E/c.
Of course, what Chronos meant to write in his last message was E[sup]2[/sup] = p[sup]2[/sup]c[sup]2[/sup] + m[sup]2[/sup]c[sup]4[/sup]. This way, the expression is indeed equivalent to p = sqrt(E[sup]2[/sup]/c[sup]2[/sup] - m[sup]2[/sup]c[sup]2[/sup]).
Because light carries momentum, any light source actually exerts a force on objects which absorb or reflect its light. If you divide both sides of the equation p = E/c by time, you get F = P/c, where F is force and P is power. For example, if a 100 watt light bulb were totally efficient and all its light were focused into a beam, the beam would exert a force of 100 Watts/c = 3.34 * 10[sup]-7[/sup] Newtons, which is on the order of one millionth of an ounce. Unfortunately, any source of light powerful enough that you could feel it with your bare hands would be more than capable of frying your exposed skin.