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Underground > Laboratory >

Energy

16:53 / 21.11.01

What is energy in science? What does the term mean?

12:38 / 26.11.01

I believe it refers to the ability to move mass through space, i.e., work.

But I'm sure there's a more thorough definition.

13:38 / 26.11.01

I thought so too before. The science textbook definition of "energy" was - "The ability to do work"

but that doesn't make sense with E=mc^2.

if you slow down the ability to do work c^2 times you'll get mass? what?

17:42 / 26.11.01

If you "slow it down," you get some alternate form of energy being generated.

Say you've got a wagon at the top of a hill, going downwards. Velocity is one form of energy. Slow the cart down, the energy isn't lost, it's being transferred to heat (and applied as force in a different direction) by the brakes.

The idea behind the E=mc^2 thing, in part, is that what we call "mass" is just another expression of energy - what we think of as solid is really a condensed jumble of forces. Electrons, mainly. And no one's sure what exactly *they* are, mass or energy, particle or wave.

At least that's my understanding of it.

It's occasionally useful to me to think of mass as the noun and energy as the verb. They're all units of grammar.

17:44 / 26.11.01

quote:Originally posted by Lionheart:
if you slow down the ability to do work c^2 times you'll get mass? what?

Any English paraphrase of the equation E = mc^2 is only a metaphor for what the equation really says about the physical world. That said, I think a more useful English paraphrase would be, “Matter converted to energy yields a quantity of energy equal to the amount of matter multiplied by the speed of light (in appropriate conversion units) squared.” Note that the conversion units are velocity squared, or d^2/t^2, so it’s not accurate to say that matter is energy “slowed down” or that energy is matter “speeded up”. The metaphor my old physics professor liked was that matter is energy tied into knots. It takes a fuckload of work to tie enough tiny little knots to make a small lump of matter. Conversely, if all those knots are severed, that fuckload of work is released, working over everything in the vicinity.

If that metaphor doesn’t help, try this link for a natural-language explanation of energy:

Energy Primer

Quimper

00:01 / 27.11.01

Energy is conserved in an isolated system.

In Newton's world, this meant various forms of energy, all added up, would equal E_total. One form of energy is kinetic energy, defined Mass * (Velocity squared)

KE = mv^2

Another is potential energy

I'm sure you've seen all this before.

Around Einstein's time, scientists were beginning to notice problems with their equations in certain circumstances. Einstein said that the principle that energy is conserved must remain true. But that the concept of what energy actually was had to change. It's basically math, really. It manifests itself physically quite well, but the big reason to use a concept of energy is so that you have a conservation principle.

01:02 / 27.11.01

Yeah but what the hell is "Energy"?

Oh and I remember reading some article in nbsome science mag or book about how matter is a form of energy. Condensed energy.

13:03 / 27.11.01

quote:Originally posted by Lionheart:
Yeah but what the hell is "Energy"?

Read the freaking link already, unless you’re just asking “what is a rose?” with an alternate noun. (A rose is a rose is a rose.)

13:16 / 27.11.01

I will not read the link until you answer my question.

Just kidding. I didn't see the link before. Thanx for it. i'm off to read it.