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Feb
24
comment Different formulas for calculating power
What do you mean "you may not want to use others if ohm's law does not apply"? If Ohm's law does not apply, then the other equations are not generally valid. You never should use invalid equations! =p
Feb
24
revised Different formulas for calculating power
improved formatting
Feb
24
suggested suggested edit on Different formulas for calculating power
Feb
22
comment Is it true that no one, not even Planck himself, knows how Planck's Constant was arrived at?
I would like note for the layman who has no practical experience with doing physics at the professional level: this accidental, trial and error approach is in fact how everything that ever been discovered was discovered. Planck's story is hardly unique here.
Feb
22
comment Ampere's Circuital Law
You are actually free choose any surface you want, as long as you choose a surface whose edge corresponds to the closed loop of current. No matter what surface you choose, the integral will evaluate to the same result. This freedom is what allows us to arbitrary choose the simplest surface possible to evaluate the integral whenever we can.
Feb
21
comment What if the surface charge on a conductor is positive?
Suppose you have two positive ions and one electron that is paired with one of the positive ions such that their combined charge is neutral. When the electron moves to the other ion, the location of an unbalanced positive charge has also moved. It is important to distinguish between the usage of the word 'charge' as a physical object for the usage as a physical quantity.
Feb
21
comment On the distinction of past and future: could one theoretically reverse direction of particles and cause time to appear to go backwards?
You wouldn't really be making time go backgrounds though. Time would still be going forwards, just in the opposite direction.
Feb
21
comment Is it possible that there is no theory of quantum gravity?
What if there is no quantum gravity? 50 years of string theory goes down the toilet, that's what.
Feb
21
comment Composition of kinetic energy
@Stopforgettingmyaccounts... Indeed, energy has absolutely no physical component. If it did have one, then its component would have its own energy, and the energy of the material part of energy would have its own material part. And the material part of energy's energy would have energy too. So on and so forth, ad infinitum, ad nauseum. But it doesn't, which is why no one's ever succeeded in making a perpetual motion machine.
Feb
21
comment Composition of kinetic energy
@Stopforgettingmyaccounts...Indeed if numbers were made of rocks, you run into a very big problem. Say you needed to count 5 rocks. Well first you would need to build the '5' that you need in order to perform the count. So go grab five more rocks to make the '5'. In order to grab the right number of rocks, you need to count those additional 5 rocks. And to perform that count, you need to go grab five more rocks! The paradox results if you try to ascribe a material component to energy.
Feb
21
comment Composition of kinetic energy
@Stopforgettingmyaccounts... Energy has no substance because energy is a property of substance. Energy is a quantitative property of physical systems that describes a system's state. As if you are trying to build numbers out of rocks every time you need to count something. Suppose you have one rock. The 'one' is merely description of how many rocks you have; the number 'one' is not itself made of rocks.
Feb
21
comment Composition of kinetic energy
@Stopforgettingmyaccounts... Kinetic energy is made from work. It's not made of anything. There's a good discussion of the difference between the phrases 'made of' and 'made from' over at the English StackExchange.
Feb
20
comment Can we expect the discovery of something that moves faster than light/photons?
It would have to be something incredibly tacky.
Feb
20
comment Why do electrons and protons attract each other?
First, go watch the YouTube video Feynman, magnets, and why questions.
Feb
19
comment where does the photon go after scattering?
Another process where mass is conversed is the electrolysis of water, i.e. the conversion of water into oxygen and hydrogen: $2\text{H}_2\text{O}\rightarrow2\text{H}_2+\text{O}_2$. The mass before and after the reaction is conserved, but the number of molecules is not. It makes no sense to ask "where did the H2O molecules go?" because after the reaction, the H2O molecules aren't anywhere. They're simply gone. In much the same way, photon number isn't conserved either. I apologize for the lengthy comments. Hopefully they'll still be helpful.
Feb
19
comment where does the photon go after scattering?
The law of conservation of mass tells us that the amount of mass of a closed system is constant; mass can neither be created nor destroyed. Suppose you weigh a pot of water before and after boiling it for some time. You'll notice that it weighs less afterwards. From the law of conservation of mass, you can infer that since the mass of the missing water couldn't have simply been destroyed, and that the missing mass will be found if we look in the right place (collect and weight the water vapor). (2/3)
Feb
19
comment where does the photon go after scattering?
Where does the flame go after you blow out a candle? Where does the sound of someone's voice go after it has reached your ears? When something disappears in one location, you have to think carefully about whether or not it's reasonable to infer that it must have gone somewhere else (as opposed to being gone altogether). The intuition that "all things must be somewhere, so if it's not here then it must be somewhere else" is justified by the various physical conservation laws (mass, energy, momentum, charge, etc.) and spatiotemporal continuity. (1/2)
Feb
3
comment How come the universe is made of matter and not antimatter?
@SajinShereef See Brandon's comment above. At the moment, you aren't really asking a question worth answering. Asking why antimatter lost the tug-o-war is like asking why the team with the least points lost. "Ordinary matter" is a label we slap in the winner, and anti-matter is a label we slap on its opposite. A better question is why is there a winner at all?
Feb
3
comment How come the universe is made of matter and not antimatter?
@WetSavannaAnimalakaRodVance Hehe, for a moment there I thought you were talking about Mike Brown the planetary scientist. I took a freshman intro geology class he taught, and I was about to be very confused how a theoretical physicist with a dissertation in frontier theoretical QFT topics transitioned into the guy who taught me how to recognize feldspar. =D
Feb
3
comment What is the future of our universe?
The ultimate fate of the Universe is a major open question in cosmology. That means physicists are trying to figure this out as we speak, and whoever does figure it out will most likely win a trip to Stockholm. It is unlikely that such a Nobel Prize winning solution will make its debut published as a response on these forums.