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One Hundred Years of E=MC2
Eric Ward writes "To mark the one hundredth anniversary of Einstein's
famous equation, E=mc2, NOVA has gone live this month with a Web site that features exclusive content and podcasts from ten of the worlds top physicists. This once-in-a-lifetime gathering of top scientists such as S. James Gates, Jr., Brian Greene, Neil deGrasse Tyson and Nobel Laureate Sheldon Glashow simplify what the equation means to our world today and the effect it has had on their careers. NOVA online also details how Einstein grappled with the implications of his revolutionary theory of relativity and came to a startling conclusion: that mass and energy are one,
related by the formula E=mc2.
Viewers will also find lesson plans through the
award-winning NOVA Teacher's Guide and a special
library resource kit."
There once was a fencer named frisk,
whose movement exceedingly brisk
so quick was his action
the Fitzgerald Contraction
reduced his rapier to a disc
+5, Truth
In response to this momentous occasion...I can only quote the great MC Hawking. :)
"I explode like a bomb. No-one is spared. My power is my mass times the speed of light squared."
Einstein's work showed that Newton's equations were a good approximation for low velocities, but not for velocities approaching c. What if Einstein's work is an approximation, too. Perhaps we will discover that the E deviates from mc^2 when temperatures are very high or very low or m is very large or magnetic fields are especially strong.
Newton's 3 laws survived 239 years, I wonder how long Einstein's will last?
Two wrongs don't make a right, but three lefts do.
But m = \gamma m_0, where \gamma = 1/sqrt(1 - \beta^2), and, of course \beta = v/c.
I.e., E = mc^2 = m_0 c^2 / sqrt(1 - (v^2/c^2))
Oh, m_0 is rest mass, in case you didn't know that, and m is the relativistic mass.
Ben Hocking
Need a professional organizer?
By Peter Norvig.
Don't miss the rest of his site while you're there.
To a Lisp hacker, XML is S-expressions in drag.
Sadly, this comes just days after the anniversaries of the Hiroshima and Nagasaki bombings.
"If Einstein was so smart how come people only call you 'Einstein' when you do something really stupid?" - Brian Regan
So what was E equal to in 1904?
++ Say to Elrond "Hello.".
Elrond says "No.". Elrond gives you some lunch.
einstein was awarded the nobel prize for his brownian paper. relativity, published the same year, was all but ignored.
source:t ml
http://www.bun.kyoto-u.ac.jp/~suchii/einsteinBM.h
2 1337 4 u!
Hm. I call bullshit. The same site appears to also support UFOs and some sort of secret Nazi base in Antartica?
Seems like a scientist's National Enquirer.
"For years, I struggled with reality... but I'm happy to say I finally won out over it." -- Elwood P. Dowd
All this business of E = mc^2 "giving us the nuclear bomb" is another example of newspaper pap-science. There's far more to a nuke than computing the mass defect.
The whole idea is a staple of Relativistic kinematics which has been verified in collider experiments, etc., etc.
You can define relativistic stuff in less than four dimensions (e.g., one of space and one of time). Take an electron-positron annihilation into two photons. A proper treatment requires quantum field theory, where mass can be understood (in one way) as a parameter constraining the dynamically allowed momentum-energy configurations of the physical ("on-shell") fields. It's [probably] not right to think of electrons as little dots of mass.
Again, you need to consider quantum field theory to [begin to] answer these questions.
But I have a few nagging question about this famous equation. People just tend to explain c^2 by saying something like "a little matter represents a lot of energy, and c is a big number and so c squared is even bigger". Well, that certainly is true if c is measured in meters per second or any other common unit. But it's all about the units. If c is expressed in light-seconds/second rather than meters per second, or worse yet light-years/second then the "logic" of that argument is exposed as just hype. So the real issue comes down not to the equation e=mc^2 itself, but the selection of the units that e, m and c are expressed in. Use a different unit and, as I try to show above, the whole thing breaks down.
Al himself made a pretty famous point of saying that c was a constant. So c^2 is also a constant. So the equation boils down to expressing an important relation between e and m. But it all depends on the units of measure. So here's the question:
Is there some science behind the selection of the units involved that allows this equation to be so simple, or are we to believe that some serendipitous magic just allows this to be an exact equation and the units somehow just happen to match up? After all, I certainly don't know of any reason why a meter is any more of a valid unit to do this calculation with than a furlong, or a foot, or a parsec. And I am under the impression that the units of both mass and energy were determined before the equation, not as a result of it. So should I believe that this equation is just a serendipitous chance match up of units, that Einstein made some sort of deal with God, or that the equation just might be a bit over simplified?
If a meter were and inch shorter or an inch larger, there would still be an equation that could show the relation between e and m, but a conversion number would have to be added to the equation to make up for the slight difference in the size of the meter. How is it that this equation works out with the current rather arbitrary length of a meter to such whole numbers?
I'm an American. I love this country and the freedoms that we used to have.
As my mass has gone up, my energy has gone down. What more proof do you need?
Another interesting fact, derived from empirical analysis : in a Windows field, light speed is negative.This explain the interesting "expanding copy time" (aka "30 seconds left... 4 centuries left...") experienced by most Windows users.Another explaination would be a schrödinger-like effect induced by closed source.
I'm jack's useless sig
100th anniversary? Yeah, but it's all relative
Please. Einstein was awarded the Nobel Prize for his work on the photoelectric effect. He did publish a fantastic work on Brownian motion as well. If you had RYFSM (read your f**king source material) you would also know that, since it says so in the first paragraph.
/. and I should be happy with that.
I guess its just
Ummm, no. Einstein's NP was for his paper on the photoelectric effect. Read your source again.
"Lawyers are for sucks."
- Doug McKenzie
I don't know if I fully believe that energy equals mass... To take mass, and BANG, the mass is gone and there is energy, does not ring true to me.
And Newton's first law of motion didn't ring true to Aristotle—clearly objects in motion tend to come to a stop if nothing is pushing them. Our intuition about how the universe works is based on our limited experience of medium-sized objects moving at low speeds on the earth's surface, with the result that all physics post-Aristotle is more or less counterintuitive. The fact that you can't imagine it doesn't mean it isn't so.
To begin: Wolfgang Pauli postulated the neutrino, not Einstein.
Next: Whatever one concludes about the validity of Eddington's solar eclipse experiment, the predictions of General Relativity have been tested and proved out in hundreds, if not thousands, of repeatable and rigorous experiments since then.
And Next:
This quote falls somewhere between the irrelevant and a non-sequitur. Thanks for sharing man--but what does it mean? No physicist takes cold fusion seriously, and autodynamics is a competing theory to General Relativity, for which Richard Moody, Jr. is clearly a shill.
At the end of the day, it doesn't matter whom it was that provided the first, or the first accurate, derivation of e=mc^2. It could have been Einstein, Poincare', or William goddamn Shakespeare, for all I care. What matters is that both Special and General Relativity have withstood an awful lot of testing over the last century, and stood up well under that onslaught.
The autodynamics camp also seems to believe that Special Relativity is used in radioactive decay calculations, and I could have sworn that Quantum/Statistical Mechanics holds sway there....
Einstein was not awarded the Nobel for special relativity because much of it was in fact unveiled by the great mathematician Henri Poincaré. Poincaré found the key point, i.e., everything stems from defining time as being obtained by synchronizing clocks with electromagnetic signals.
Not really. Poincare did do a lot of the interesting math, following on from Lotentz, that provides a lot of the mathematical foundations for relativity, but what he didn't do was redefine time. Poincare still viewed the different time in the calculations as a sort of "local time" which was in a sense merely a mathematical fiction required to make the calculation go through. Poincare still believed in the ether, and thus an absolute referene frame and an absolute time. It was Einstein who, with his observations about the very nature of time being relative, did away with a ficntional "local time" and an absolute reference frame. In Einstein's view there was no true reference frame and all time was "local time" - local to the observer. The effects on time were thus not a mathematical fiction, but a physical reality. It was this observation and new conception of time that Einstein is highly regarded.
That does not, of course, in any way diminish Poincare's work - and he did a great deal of work besides just that relating to relativity (he is the father of algebraic topology for instance). Certainly Poincare deserves a little more recognition for his great achievments than he gets outside of the mathematics community. Misrepresenting Einstein's achievements is not the way to give Poincare his due credit however.
(As a side note, more recognition should probably also be given to David Hilbert, who did a lot of the pure maths required to lay the foundations of General Relativity).
Jedidiah.
Craft Beer Programming T-shirts
"When you are a student, it's called plagiarism; when you are a professor, it's called scholarship."
But for all I know he ripped that quote off from someone else . . .
If we are getting pedantic...
[PEDANTIC]
For things like photons that have zero rest mass
E = m0*c^2 / sqrt (1-(v/c)^2)
Doesn't work so well... By using the following:
(E^2) = (m0^2)*(c^4) + (p^2)*(c^2)
Now photons (which by definition are moving and have momentum) can have kinetic energy associated with them without having to divide zero by zero (since photons travel the speed of light v/c = 1 and the denominator is zero in your equation).
[/PEDANTIC]
I realize it's gauche to reply twice to the same comment, but there were a couple things I didn't answer:
What did E=MC2 give us the past 100 years?
It's a fact (approximately) about the nature of the universe. It doesn't need to give us anything. What did the discovery of the planet Neptune do for us? Nothing practical, but I think knowledge is worth seeking for its own sake.
What I think is more useful from E=MC2 is the idea of relativity. It is true, not just for science, but for almost every field of study.
If by "the idea of relativity" you mean, roughly, "there are no privileged inertial frames of reference", then I have a hard time imagining what bearing that idea has on, say, art history, or comparative religion. If you just mean that "everything is relative", then I'd say that your idea of relativity has very little to do with Einstein, and is probably too vague to be much use in any other field, either.
Nope. Grandparent is completely correct (even though he says he's not in a later post). Burning is exactly analogous to nuclear reactions. Bonds are broken and energy is released. In both cases, matter is converted into energy. It does not matter whether the bonds are electromagnetic (chemical) or strong (nuclear).
.04 milligrams.
In chemical reactions, the amount of mass converted to energy is very small and nearly impossible to measure, but that's not the point.
Example: To heat your house, you use on order of 1000kWh per month, obtained by burning natural gas. 1000 kWh = 3.6 * 10^9 Joules. E=mc^2, solving for m: 3.6 * 10^9 J / (3 * 10^8 m/s)^2 = 4 * 10^-8 kg =
My credentials: I'm a graduate student in physics at the University of Minnesota.
When I talk to "scientists" (I'm not one either), and even hint that Einstein's theory might be wrong, it's as if I've shouted out a stream of profanities at church.
it's not because they thought you shouted profanities in church, it's because you're showing remarkable lack of understanding of the scientific method and how science is done. if you want to be taken serious, propose your model, show how it explains an observable fact that current theories don't.
being a physicist, i can't believe your post. do you really believe what you say? more importantly, does anyone else? not only is your 'discourse' lacking in supporting evidence, but it's clear you don't know how science is conducted.
one does not simply accept something that's published because it's published. yes, it makes a difference what journal, but that is what references are for- a paper which doesn't give enough details to be reproduced is useless.
have you heard of tenure? it's very hard to get fired if a professor has tenure regardless if he puts forth crackpot theories. to suggest scientists are priests and are afraid of dogma is unfounded and completely false. it's hard to disprove a standard theory simply because the standard theories are the cumulative sum of all of mankind understanding.
physics always consider alternatives. how else do you advance understanding? it's the willowing of all these alternatives that have given us relativity, quantum mechanics, statistical mechanics, electromagnetism, etc.
really, the natural sciences are not a religion. it has to do something, everytime. "objectivity" not "clinging to tradition" is what insures your computer works, electricity is on, gets a probe to Mars, etc.
i do hope you are simply a troll...