PBS Features Einstein's Famous Equation

porp writes "On Tuesday, October 11th at 8PM EDT, PBS will feature a docudrama about Einstein's discovery of his famous E=mc^2 equation. The program will include details explaining those who came before him and the development of his miracle year. The pinnacle of which according to the program was his discovery that matter and energy are two sides of the same coin. Yahoo summarizes the program details in length." From the article: "Based on David Bodanis' best-seller 'E=mc2: A Biography of the World's Most Famous Equation,' the program explores the lives of the men and women who helped develop concepts behind each term: E for energy; m for mass; c for the speed of light; and 2 for 'squared,' the multiplication of one number by itself."

Comments

Get the formula right.

[Pudusplat]

E = [(p2c2) + m2c4]1/2

Re:Get the formula right.

[pmj]

If you are going to be pedantic, you should at least put in the right form of the equation.
E=[(pc)^2 + (mc^2)^2]^(1/2)

Re:Get the formula right.

[Anonymous Coward]

p is for momentum, the rest has been defined already.

Its basically taking E^2 - (pc)^2 = mc^2, and the reason this is chosen is because its an invariant quantity, meaning its the same in all inertial reference frames(Real good thing to have to translate between frames).

Re:Get the formula right.

[mako1138]

Note that the page you mention is a mirror of the Wikipedia article on mass. And it doesn't really have anything to do with quantum mechanics - we are taught non-relativistic (and time-independent) QM in undergrad courses.

The main things to take from E^2 - (pc)^2 = (mc^2)^2:

1. Set the mass m equal to 0. We get E = pc, or p = E/c. Thus momentum is defined for massless particles in special relativity. Newtonian mechanics can't handle this correctly.

2. Set the momentum p equal to 0. We get E = mc^2, popularly known as energy-mass equivalence. There's subtleties to it, though; see Relativistic mass.

Already out on digitaldistractions

[mailman-zero]

If I'm not mistaken, this is the same documentary as here.

It's a pretty interesting show.

Re:Is this new?

[mailman-zero]

The torrent is here.

I checked this out a few weeks ago. It's really an interesting show depicting some of the greats that preceeded Einstein as well.

Seen it already

[Gabhlan]

It was on over here in Scotland a few weeks ago. Nothing to get worked up about, it's been hideously dumbed down as you'd expect of anything on TV these days.

Rest Mass

[Joffy]

People should realize that the M in e=mc^2 is not the widely known idea of mass. Most people think that a bowling ball that weighs 10 pounds has a set mass no matter what. But in Einstein's equation mass is more like inertia. A moving bowling ball has more mass than one at rest. So you can not simply take a 10 kilogram object and multiply it by the speed of light squared to get its energy. This means you must first complete the equation for m first, which I do not know off hand.

So the idea of mass that most people know is called rest mass. It took me a while to realize that they meant an object could increase mass but gain no atoms or extra "material". Since most objects we can see and touch don't even go 1% the speed of light, we never notice this increase. For almost all practical cases(even a plan going mach 3) we can consider its mass to be rest mass and still be accurate to within many many decimal places.

Re:Rest Mass

[Anonymous Coward]

Most people think that a bowling ball that weighs 10 pounds has a set mass no matter what

And they would be right, to within what they actually can perceive.

If they were trying to push a bowling ball moving at 99.9999% the speed of light, their concept of mass would still agree with that of Einstein's mass.

I really enjoyed it

[FunkyRat]

I had no idea about Faraday's background in poverty or that Lavoisier was the Paris tax collector and subsequently beheaded in the French Revolution.

Oh, and as a bonus, it's narrated by Christopher Eccleston. Half expected to hear a metal scream ring out at any moment. "Exterminate!"

Re:Neat but one burning question

[orbitalia]

I think most of the responses to the parent question have missed the intention of the original post.. There is a theory of VSL (variable speed of light) even for c, with the speed of light in a vacuum changing over time (most notably championed by Dr Joao Magueijo of Imperial College London) If you are so inclined you can read the paper yourself here

Re:Measurement Units?

[Daniel Dvorkin]

Think about it this way: if you measure c the way you'd normally measure velocties, say in meters / second, then you get c^2 in units of meters^2/seconds^2. (IIRC, c ~= 3 * 10^8 m/s, so c^2 ~= 9 * 10^16 m^2/s^2). But let's say you want to measure velocity in units such that c = 1 -- say, measure it in light-seconds/second. Then c^2 = 1 ls^2/s^2, this is true.

But a light-second is huge, and a light-second squared is even huger. In fact, of course, 1 ls ~= 3 * 10^8 m, and thus 1 ls^2 ~= 9 * 10^16 m^2. (Again, IIRC.) Try translating that into units that make sense on an earthly scale: if I throw a 1 kg weight at you at 1 m/s, you're going to feel the impact when you catch it. Now think about that scaled up by almost 17 orders of magnitude.