Is this a school assignment, Old Sport? That's what scientists refer to as one of the laws of thermodynamics.

I'm serious, I want to know who was the first one who said that.

I'm assuming it's in here somewhere: http://en.wikipedia.org/wiki/Conservation_of_energy#History

I'm not sure who said the actual quote, but Joule and Helmholtz are the people who figured out the concept.

I'd say Einstein but I'm not sure.

I've definitely said it, but I don't think I was the first.

Discoveries are rarely attributed to the correct person (Arnold's law - http://www.phy.bris.ac.uk/people/berry_mv/quotations.html), so maybe we should watch out for Maniac's law.

What is energy?

God

You rang Thucy?

So, masturbation is God's work? Transforming God into a God by friction?

"What is energy" is always a good question in a physics thread.

i was sure Newton did,but a someone said it was Einstein ,i can't find a conclusive answer.

Newton certainly did not. That was not known for almost 200 years after Newton.
It was known about 60 years before Einstein.

Lavoisier spoke about mass conservation, and Einstein (much later) about mass-energy conservation. About energy alone, I thought Joule to have been the first to specifically speak about equivalence (surely he was the first to experiment the potential energy to heat conversion), but then I checked on wikipedia finding this:

http://en.wikipedia.org/wiki/Mechanical_equivalent_of_heat#History_and_priority_dispute

so it seems that the quote actually belongs to Helmholtz... ("Hermann Helmholtz in 1847 published what is considered a definitive declaration of the conservation of energy. Helmholtz had learned from reading Joule's publications, though Helmholtz eventually came around to crediting both Joule and von Mayer for priority.")

Wasn't it Doctor Who? ;)

thanks Breathofvega!

lmgtfy.com/?q=+“Energy+cannot+be+created+or+destroyed%2C+it+can+only+be+changed"

i found this:
One of most basic laws of science is the Law of the Conservation of Energy. Energy cannot be created or destroyed; it can only be changed from one form to another.

Energy is not currently being created. The universe could not have created itself using natural processes because nature did not exist before the universe came into existence. Something beyond nature must have created all the energy and matter that is observed today. Present measures of energy are immeasurably enormous, indicating a power source so great that "infinite" is the best word we have to describe it.

The logical conclusion is that our supernatural Creator with infinite power created the universe. There is no energy source capable to originate what we observe today.

not so logic! lol

The laws of the conservation of energy and matter respectively are the two biggest holes in the idea that there is no God

Clearly, there must be a God or we have to throw out those laws.

@Gunfighter: I believe you mean "Clearly, there must be an exception or we have to throw out those laws". God is not necessary, just some exception to those laws under some circumstance.

You can't see energy as you can't see God.
But what's worse is that I can't find my wallet today.

i can't see how the laws of the conservation of energy are a way to say there is or isn't god.
so the universe creates itself time and again with the same "infinite amount of energy".
yes,no one knows how it started but it's only because we are small and insignificant humans.
humanity is a grain of sand in history just as the universe is just a grain of sand in time.

the only infinite thing is "time"

Given the fact that the total energy in the Universe is very likely zero and the mass–energy equivalence holds (there was once this fellow called Einstein), the God is once again completely unnecessary.