What does E=mc^2 mean?

Maybe I misunderstand, but I don't think of it that way and I don't think most others do either. Doesn't E=mc^2 help us realize that energy and mass are ultimately quite similar, but just in different forms? Kind of like how ice and water are ultimately quite similar, but in different forms.

i seen a movie clip but i was verrrrry young about Einstein getting the whole e=mc2 idea... wasnt it inspired by fire?

thats funny to realize i have no clear definition on what e=mc2 is... and yet its used so common as an illustration of knowledge...

... do you mean something like string theory? ...

'E' = energy
'm' = mass (grams)
'c' = the speed of light in a vaccuum (ideal)
^2 = 'squared' (times itself, ie; 2 squared is 4; 4^2 = 16)

So Energy is/equals/the-same-as (not 'similar' to) mass (in grams) travelling at (times) the speed of light squared (186,000 mps x 186,000).
They are equal, but for 'Perspective'.
Energy is the same as fast mass; 'stuff/things' are the same as 'slow energy'.
And so exhausts my meager understanding. The net is just chock-full of tutorially natured sites for the layman, about this stuff (slow energy!) if 'really' interested.
Peace

Why is the speed of light squared and why is it even in there?

Light is massless and constant!

Is there such a thing as the speed of light?

What they did was two guys set up an elaborate set up of mirrors from mountain to mountain and timed how long it would take for the other to see the beam of light flashed at them through the mirrors. Probably during the night and using special sensitive technology.

Thats how they determined the speed and so far there's nothing that can travel faster, though if it is the infinite universal speed, it could be said its not moving. A relative point of max and min would work the same in equations right.

Whether or not light is massless and constant, a wave or a particle, an x or a y...is a good question, and not a fact, yes or no. In "fact", the answer may well be...sorta. Are you familiar with the bending of light around the event horizon of black holes (or even as it passes planets and such) and the very easy to observe "wave effect" of multiple lights on a flat surface?

The other problem here is "the speed of light in a vacuum". As true vacuum (ie "nothingness") does not exist (non-existence does not exist...eh?) according to all observed perspectives and theoretical models thus far, the injection of a potentially impossible condition into the equation seems to answer a question by raising another.

Yes, Einstein provides plenty of grist for the mill.

rather simply, c (m/s) is squared so that when it is multiplied by mass (kg) the result is in the correct units for joules

ie



why is c there? it has to do with the derivation (after all physics is applied math) Mass?energy equivalence - Wikipedia, the free encyclopedia

My crude understanding is that the formula E=MC^2 is to mathamatically depict motion. As with any formula, if you can proov it is valid (pradictable) you can use it to deduce information from the data you have. If you know the mass and the velocity you can then deduce the energy. If you know the mass and how fast you want a satalite to travel you can deduce the energy you deed to apply to make that happen. From what I can tell, It doesn't matter that the speed of light is not constant, because it's just a mathimatical constant that works (like pi).

I am trying to pick thru your statements and it seems you have doubts about what Einstein's famous formula does. Let me assure you the formula is absolutely fundamental to physics. You mentioned mass, velocity and energy.

In particle collision machines it was quickly found that when particles were accelerated they gained mass and the faster they went the harder it became to move them to even greater speeds.

Einstein had predicted this effect and he stated that at the speed of light the particles would have an infinite mass and it would take an infinite energy to accelerate them, which clearly is impossible. He also predicted that the increase in mass would be real in that if the particles were suddenly stopped in a collision then there would be more mass than the starting mass. This is like claiming that if you threw a glass bottle to the ground then picked up all the pieces and weighed them then you would have more glass than what you started with. However, this transient effect has also been confirmed in particle accelerators.

So, what are we to make of this? As the fictional doctor Niles Crane once said as he hurried out the door, "I do not like to leave my sexually obsessive class alone together too long". I think he also neglected his class of particle physicists.

It seems it all depends on what you think a particle is. In the case I've mentioned it is a handy analogy to think of the result as similar to throwing a stone into an already very wavy pond. But not all experiments with particles can be thought of in terms of waves (not yet anyway) because just when you think particles must be waves along comes an experiment which requires the particle to be a bullet.

It seems science has come a long way since particles were first detected and were then thought of like peas in a can. Who knows, maybe they will eventually be treated as small wave structures being shed from larger wave structures because what the standard model now expects is for us to think of particles in the atom being much like sparks in layers filling a car battery, which yet could be true of course.
I hope this helps.

Thank you bracewell. Yes I understand that mass and energy are transmuted as speed increases so nothing can really travel the speed of light because its mass would increase as it sped up and would then require more energy. Now mass and energy are transmuted one to the other. Strangley enough, time (what we previously assumed was a constant) would actually slow down as you aproach the speed of light.

But was I correct in my post about the practical ways that the formula is used to calculate motion? Sort of the sumation of newtonian physics.

The part you are refuring to in your post that describes matter as a particle and a wave at the same time is really from Heisenbegs uncertainty principle, no? This is the birth of quantum pysics and Einstine hated this Idea famously stating that god does not roll dice. I find this fascinating but we should starta new post if we want to talk about theories other than E=MC^2.

I have to intervene here. Mass and energy is NOT physical particles and light. And the speed of light is determined through the solution to Maxwell's equation in a vacuum. The fact that light travels slower in different mediums has nothing to do with the Maximum speed of the universe. The speed of light in a vaccuum implies the maximum speed of light which is the maximum speed of the universe.

E=MC^2 simply implies that Energy and mass are interchangable (Not energy and particles). When mass dissapears in a Nuclear reaction (particles dont dissapear, the mass simply varies slightly) the energy realeased is equal to the mass loss times the maximum speed of the unierse squared.
Energy is also present in Charge, but Charges cancel out. Mass doesnt cancel out and thus it is absolute energy.

This is a bit off thread but I have a question about the maximum speed of light.
If near a massive star we could observe scientists testing the speed of light would it not be true they would find it to be exactly the same speed as it is here? However, if we could see their clock and compare it to our clock then we would see the two clocks running at different speeds?

I can't comment on what else you wrote and that is my fault as I rely on others for interpretation of the standard model. However, I respectfully suggest you construct your posts using a word processing programme and then copy it across.

Nope, I can't see the connection between Newton and Einstein on this subject so you are just going to have to explain more. However, I believe there is a loose connection between the two on the subject of gravity.

Binyamin I have re-read your post often and I am still not sure if I am interpreting it correctly but here goes.

I think what you are saying is that particles should be thought of as permanent structures so that when light passes through glass then the same particles emerge as entered.

If this is the correct interpretation of your post then I am not sure there is the evidence for this, conventional as it might be. It is possible particles are repeatedly absorbed and re-emitted on the passage through glass. In an analogy this would mean a crowd of Manchester United supporters entered and a crowd of Liverpool supporters exited, or to put it another way, it may not be possible to give particles personal names - like Bob, Annabel or Phil the photon.

There needs to be an explanation why there is a reduction in speed when light passes through glass or any other medium.

Hey Bracewell, I thank you for your suggestion about using the spell check. I'm not educated as you may have already guessed. Sorry for the trouble.
Now back to the discussion: I may have been wrong about my idea of this formulas use in describing motion.

I fully agree with what Binyamin is saying. Mass and energy are interchangeable and the maximum speed of anything is the speed of light through a vacuum. So as you speed up, your mass would actually increase, requiring more and more energy. So this speed of light is like the speed limit. Observed time would slow down as you go faster and faster (not sure why). Scientists always assumed time was the constant, but it turns out that speed of light was the constant. The reason that the speed of light is squared has something to do with motion/inertia. If you drop a steel ball into a tray of clay, and then increase the distance it falls by two, the impression it makes will increase by four times (squaring the inertia). This is the connection I was making with Newtonian physics.

Although Newton pioneered the concepts of inertia and the force of gravity holding a planet in orbit his math was incomplete up until Einstein's theory of special relativity (E=MC^2). I may be totally wrong though (I struggle when others fly).

As for light being a particle that passes through glass: one must dabble in quantum mechanics. Light was long thought to be a wave (indeed it is a wave) an electro motive force like radio waves micro waves or x rays. But it turns out that light comes in packets (particles) called photons. Photons have varying energies and therefore, varying wavelengths. The variations in wavelength are what make things appear to have color. A green apple absorbs all the visible wavelengths except the green ones that are reflected back to your eye, making the object appear green. Light passing through glass is not affected much (at least not the visible light range). Whenever light passes through anything it will lose some energy though. Some of the wavelengths are altered, and some of them are reflected. Generally longer wavelengths have more energy and travel farther than shorter wavelengths.
Anyone is welcome to jump in and set me straight, I'd rather be corrected than continue in my ignorance.

thanks

The speed of light in any medium is solved using the Maxwell Equations. They are equations that were originally used for electric fields and magnetic fields and when light was discovered to be an electro-magnetic wave, the equations were solved and we came up with the speed of light.

Ogden, the planetary motion was not solved by E=mc^2 but by Einstein's General Relativity.

Bracewell, you are also slightly correct. Einstein's first paper was on the Photoelectric effect. This is when an electron absorbs the photon energy and then re-releases the photon at a later time or is shot out of its orbit by the photon's momentum. But this is only for high energy photons.

The phenominae that you are speaking about (The slowing of light through media) is due to the electric fields around particles.

Thanks Ogden and Binyamin, it all sounds good to me.

Yes, I like it as well and want to ask biyamin to elaborate on why the speed of light is squared, and how time fits into the equasion please.

Here is a great PBS Nova program on E=MC2, but you have to catch it at the right time.

NOVA | Einstein's Big Idea | PBS

Otherwise, the site has some usefull info.