Does light have weight? Does light make sound?
First, what is weight? Stand on the bathroom scale and you get your weight. Take that same scale to the Moon and your weight changes (it's lower). Gravity is weaker on the Moon.
Weight is force. In physics we talk about mass as the property an object possesses that is the same under all magnitudes of gravity. If you know the strength of gravity at a particular place and you know the mass of the object, you can calculate its weight.
Light is made up of particles called photons, and photons have no mass, so they have no weight. However, a strong gravitational field can bend light and that sounds like they do have mass. Why is that? Einstein says that mass and energy are equivalent. Light has energy, so its path can be changed by gravity.
We say it has no mass and no weight because it has no energy associated with zero velocity. We call this the "rest mass", and for photons the rest mass is zero. Ordinary matter like protons and electrons have a rest mass, so we say they have nonzero mass and nonzero energy associated with zero velocity. Protons and electrons respond to gravity the way we expect particles with mass to respond, and they are the reason each of us has mass and weight.
Sound, unlike mass, is a characteristic of the medium. If you can get air molecules to move together to transport momentum through the air, that motion is sound. Moving air molecules is what the speaker in your radio or phone is designed to do, and electromagnetic fields working with a magnet make the speaker move. Photons are the carriers of electromagnetic fields, so in that sense they can create sound by interacting with objects having mass. The photons we think of as light would be harder to harness in this way, but you can bet that somewhere someone is building a very small device to do just that.
Source: NASA
http://www.wisteme.com/question.view?targetAction=viewQuestionTab&id=16142
i am not into physics and stuff i m from a different field but just for curiosity i m asking that the universe is 74 percent dark energy and 23 percent dark matter as u said that the light is made of photons which have 0 rest mass is their a possibility that the dark matter is made of something that has negative mass i.e it sucks in the mass or photons thus leaving no scope of light to be produced...and that is how the dark matter pushes or rather pulls the universe towards it the higher the pull the more universe expand towards it...???just asking out of curiosity...
ReplyDeleteTwo objects that have mass attract each other. A "negative" mass should then be expected to repel an object of "positive" mass. I don't believe that such a phenomena has been observed so negative mass would just be hypothetical.
ReplyDeleteThe reason we believe dark matter exists is because astronomical bodies (galaxies) appear to contain more mass than we can see. So where is all the other stuff that should be there? This is what we call dark matter. Since this theoretical dark matter isn't visible, we assume that it does not interact with electromagnetic forces. It neither absorbs light or emits light, it simply doesn't care that light is there.
Dark matter isn't actually dark though. If we put some in a pile in a bright room, it's not like it would look like this dark glob of mysterious stuff. It would literally be invisible!
So we assume dark matter has mass (!) but it doesn't interact with photons. It behaves just like all other matter, it pulls other objects that have mass towards it, we just can't see it. What kind of matter could this be? How can we see it? What experiments could we run to determine all of its properties? These are all good questions that the idea of dark matter leads to!
Hope that makes sense and answers your question :)
Light,given the appropriate mathematical circumstances, and setting resonates releasing sound, I have done it and recorded it.
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