Yes hello, is it possible for something to weigh nothing? Does light have a weight?
This is a really complicated question to answer, mostly because of semantics. First, let’s talk about the difference between weight and mass.
Weight is the effect of gravity on an object. It is proportional to an object’s mass, but if the object is unaffected by gravity then it weighs nothing, regardless of its mass. In addition, objects in orbit or under the effect of buoyancy behave as though they are weightless.
Mass is a characteristic of an object, a measure of the amount of matter contained by the object. In other words, mass is the object’s resistance to being accelerated by any external forces.
So, just based on those definitions, it is theoretically possible for an object to weigh nothing. In fact, astronauts on the ISS would say that they are weightless.
In addition, it is theoretically possible for an object to be massless. Photons, the carrier particles of light, are massless particles. But photons don’t always act like they’re massless. This is because, in general relativity, there are actually two types of mass. There is the invariant mass, which is the traditional mass, and the relativistic mass, which has to do with an object’s momentum.
To answer your second question, no, photons are massless (so they don’t have a weight). But also yes, because a box of light would actually weigh more than an empty one because of this relativistic mass. Unfortunately, until we get even better at physics than we already are, this is the best answer I can give.
If you want to learn more, check out these links: HowStuffWorks, University of Illinois, The Naked Scientists, Philip Gibbs’s Does Light Have Mass
gracieabrams
