Wednesday, 9 June 2004, on the EFnet IRC channel #Mensa [00:38] * @gloriae- goes to search engines to find if there are any physicists who think light has mass and if so how they proved it [00:40] <@gloriae-> Original by Philip Gibbs 1997. Does light have mass? The short answer is "no", but it is a qualified "no" because there are odd ways of interpreting the question which could justify the answer "yes". ... [00:41] <@gloriae-> according to theory, a photon has energy and momentum but no mass [ http://math.ucr.edu/home/baez/physics/Relativity/SR/light_mass.html ] [00:41] yes, light has mass, all of the electromagnetic spectrum does. in my way of looking ath things [00:41] <@gloriae-> but E = mc^2 (a quantification of energy) is expressed in terms of mass [00:41] <@gloriae-> sooooooo [00:43] since when is light heavy? [00:43] just try moving a light house ... [00:44] photons have an mass? [00:45] asolipsis: nice answer, but very vague.. [00:46] getting technical requires many blackboards [00:50] <@gloriae-> "According to theory it has energy and momentum but no mass and this is confirmed by experiment to within strict limits. [00:50] <@gloriae-> "Even before it was known that light is composed of photons it was known that light carries momentum and will exert a pressure on a surface. [00:50] <@gloriae-> "This is not evidence that it has mass since momentum can exist without mass." [00:51] <@gloriae-> "What is the mass of a photon?" http://math.ucr.edu/home/baez/physics/ParticleAndNuclear/photon_mass.html [00:51] whether it has mass or not is not important, what's important is if it exerts a gravitational pull [00:51] * sol_makou grins at his paradox [00:51] so.... [00:51] anyone wanna chaos? [00:52] sol youre like, deeply in love with yourself tonight [00:52] photons have mass, otherwise why would a gravity have an effect on it? [00:53] ie, the refraction of light by the sun, black holes, etc. [00:53] <@gloriae-> refraction of light by the sun = meaningless [00:53] <@gloriae-> light refraction is not a gravitational effect [00:53] by the sun it is [00:54] <@gloriae-> did you mean deflection? attraction? [00:54] eep, sorry, how about bending of light by the sun [00:54] <@gloriae-> this FAQ says the problem is that people are using two different definitions of mass [00:55] in my little theory, the lower the energy of em wave, the larger the mass, the higher the energy ie x-rays/gamma rays the lower the mass [00:56] gravity bends space [00:56] and time [00:57] howdy yall [00:57] so it effects light even though it doesn't have mass [00:58] <@gloriae-> "The overwhelming consensus among physicists today is to say that photons are massless. [00:58] <@gloriae-> "However, it is possible to assign a 'relativistic mass' to a photon which depends upon its wavelength. [00:58] <@gloriae-> "This is based upon an old usage of the word 'mass' which, though not strictly wrong, is not used much today. [00:58] <@gloriae-> "See also the Faq article 'Does mass change with velocity?'" [00:58] asolipsis: that works in your theory for the sun, but what of a blackhole with higher energy waves escaping yet lower energy waves being held captive at a larger event horizon? [00:59] in my little theory the mass is negligible, but still is there [00:59] sol: some of the em travels faster than the speed of light and escapes due to relativistic effects [01:00] im not aware of the difference in wavelengths that escape [01:00] speed should have no bearing on something that is massless, only on the kinetic energy [01:00] and kinetic energy relies on mass [01:00] 'kinetic energy' on a quantum level really doesn't make much sense [01:00] sure it does [01:01] just because the other forces at work often make it negligible, doesn't mean it's not there [01:01] and photons are basically 'pure' energy since they're 'massless' so im not sure what youre refering to [01:02] just because the general consensus is that they are massless doesn't mean that they are correct [01:02] particles with thousands the amount of mass of any possible photon escape from black holes [01:03] not from within the event horizon of a light particle that i'm aware of [01:03] err, photon = light particle, probably shouldn't use that phrase in this conversation [01:04] mass is probably a particle too, something that creates 'stickyness' to space [01:04] ? i don't follow [01:04] what is mass? [01:05] mass is the gravitational strength emitted by an object [01:05] i think that's the short definition [01:06] why would a massive object continue basically on its original vector after colliding with a small object? gravitational force? [01:07] mass creates interia, which in itself is an unexplicable phonomenon [01:07] gravitional force isn't small, it's the negative energy equal to the total of all the mass and energy in the universe, in my little theory [01:08] i don't follow, what massive object your referring to asolipsis [01:08] im glad i dont live in sol_makou's universe [01:08] sol: doesn't matter [01:08] lets say hydrogen and uranium smack into each other [01:09] i'm listening asolipsis [01:09] at the same velocity, the hydrogen is deflected much more, because the uranium is far more massive [01:09] quite right [01:09] so what is this mass? [01:10] the kinetic energy of the uranium atom is higher than that of the hydrogen [01:10] its basically the ability of the uranium to 'stick' to space better than the 'smaller' hydrogen [01:10] the definition of kinetic energy is based on the mass of uranium [01:10] hmm, i wouldn't use the term "stick" but i understand what your saying, i think i'm on line with your theory [01:10] or the mass rather [01:10] mass and velocity, right [01:11] well, nobody has really figured out what mass is [01:11] mass is the gravitional pull exerted by an object :/ [01:11] its just kind of taken for granted that some particles posses this property, but its not understood [01:11] no, mass bends space, which is a very small side effect compared to inertia effects [01:12] when a hydrogen atom hits a uranium one going say .9 c, the gravitation effects have almost nothing to do with their resultant vectors [01:12] mass doesn't bend space... or can you give me an example of such? gravity bends space, and any massive body exerts gravity, so indirectly yes i guess you could say that [01:13] both masses are extremely small, but the difference does make a, well.. difference. [01:14] think even H-4 to urnium-234, still is almost 60x more massive [01:14] sure, a tiny tiny one, but nothing compared to their vectors, velocity and mass [01:14] gravity is a part of mass.. you can't seperate them [01:14] gravity is a function of it [01:15] the vector of the hydrogen isn't going to make much of a difference on something that is commonly 200x it's mass [01:15] the velocity can, if it is great enough [01:15] its going to make a lot of difference in the hydrogens resultant vector after the collision [01:15] would have to be some 15x faster though [01:15] in the hydrogens yes, but not to the uranium, sorry should have clarified [01:16] indeed, and why not, because the uranium has more of this magical something that makes it harder to deflect [01:17] it has a greater amount of subatomic particles [01:17] indeed, and each of these has some mass [01:18] but what is mass? [01:18] mass is the amount of gravitional pull exerted by an object :/ [01:18] that's a backwards definition [01:18] if you insist [01:18] gravitational pull is related to the mass of an object [01:19] pull is also a bad word [01:19] and completely wrong [01:19] in my line of thinking, gravity + anti matter + dark energy = matter + energy [01:19] heh, talk to [Time] about that one [01:20] so considering mass = gravity makes perfect sense to me [01:20] Timeless: you awake? [01:20] and why did you ever change your nick from [Time]?? [01:20] in my little theory matter doesn't really exist like we think, and everything is really an interaction of forces [01:21] do you believe that there is a surplus of energy in this universe? [01:21] you mean expansionary? [01:21] ie that energy + mass is of a greater quantity then the opposites [01:22] i think we have a poor understanding of what the opposites are [01:23] and 'dark energy' and 'dark matter' are just hooey, like einsteins cosmological constant [01:23] well you must believe in anti particles [01:23] correct? [01:23] on theory that's been advanced is that back holes are far more massive and far more common than we expect [01:23] one er [01:24] they can be measured by their gravitional pull, which is how all things are weighed btw, we don't measure mass, it's impossible, we measure weight. [01:26] <@gloriae-> the m in E = mcsquared is what is commonly called 'relativistic mass' m sub r, not the more usual 'invariant mass m' [01:27] <@gloriae-> that is, the m derived from Einstein's equation is what is meant by 'relativistic mass' [01:29] we can measure mass, we know the 'mass' of particles and the composition of atoms and can derive 'mass' w/o weighing it on a scale or measuring its gravitational forces [01:30] M = (m)/[1-(v^2)/(c^2)]^1/2 where M = invariant mass, m =relativistic mass [01:30] <@gloriae-> the old riddle can be updated to "which weighs more, a ton of feathers or a ton of light?" :P [01:31] unfortunately there is no such thing as a ton of light [01:31] gloriae-: as per the common consensus, a ton of light is a paradox [01:31] <@gloriae-> IFF light has mass, then it's conceptually possible [01:31] <@gloriae-> if it doesn't, then no [01:31] helpful