Why the law of conservation of energy is considered to be a valid one?

Question

Because of the law of conservation of energy the possibility of a perpetual motion is excluded, but the Universe itself is in a perpetual motion, so on what basis should we consider the conservation of energy as a law?

Answer 1

You seem to have motion and energy a bit confused.

Conservation of energy simply means that energy is neither created nor destroyed, it only changes form. Perhaps the most famous changing of form is the one relating mass and energy, E = mc².

And the Universe is -not- in perpetual motion. One fine day (many billions of years intothe future) the Universe will eirter:
a. Fall back in upon itslef (in what has been refered to as the 'Big Crunch'), or

b. it will continue to expand until all of the availabile energy is nearly zero in any finite volume.

This is called the 'Going out with a bang or a whimper' question, and the answer to is is largely unknown.

But to answer your question, the law of conservation of energy has never been observed to be violated. And it explains a bunch of natural phenomena.

HTH ☺


Doug

Answer 2

According the physical laws, the total mass and energy of the universe is constant. What we see, are the following types of physical processes in the universe:
1.The conversion of mass into energy and sometimes the opposite. For example, mass is converted into energy inside the stars.
2.Not all parts of the universe has the same amount of energy or mass. This inhomogeneity results in the flow of mass and/or energy from one place to another.
3.Some complex systems , like life which converts the chemical energy into other kind of energy like mechanical etc.

In all these above processes, the total mass and the energy of the system of all particles (material or energy) in the universe, remains constant. This is one of the fundamental laws of nature, never have been proved wrong.

The ultimate fate of the universe is a pretty uninteresting state of particles of matter and energy with maximum entropy. As the universe is still expanding, everything will move away from each other and the clusters of matter will be diffused into uninteracting bunches of particles, roaming around the space, for ever.

Had the conservation of mass-energy not been valid we could have constructed the perpetual machine.The definition of a perpetual machine is something that keeps on working without any energy input.
See: http://en.wikipedia.org/wiki/Perpetual_motion_machine

So far, nobody has ever been able to make one , nor anybody has found one in any quarter of the universe.
http://www.physicsforums.com/showthread.php?t=29697

Answer 3

Actually, the universe is not a perpetual machine. Just an extremley efficent machine. If classical physics is to be believed, the energy in the universe that runs this machine will slowly be transferred into useless forms of energy, which will eventually reach equillibrium. This prospect will take many billions of years, but it is the eventual fate of the universe according to the Second Law of Thermodynamics.

Answer 4

The law of conservation of energy is considered valid because it leads to correct predictions. It has nothing to do with perpetual motion: that is proscribed by the laws of thermodynamics -- which also lead to correct predictions.

Answer 5

It was originally derived fromobservation, and assumed to apply to all systems by extrapolation.

However, in modern physics it arises naturally out of mathematical symmetries. It is what is known as a gauge conservation law - that is, it arises from the gauge invariance of the laws of physics.

Now that sounds all very technical. What does it mean? Well, the laws of physics do not change under transformations - for instance, if I turn around (transform my coordinates) I do not expect the laws of physics to suddenly change. Gauge theories simply say that these global rules of symmetry also apply locally. In other words, not only does my tunring round not change the laws of physics for me, it does not change them for you either.

It can be shown that conservation of energy follows from this very simple symmetry principle.

Answer 6

law of conservation of energy is a valid one - when it is tested theoretically as the energy is mortal and can never vanish.
energy is nothing but smallest particles of matter.
our universe continues to move so is there a loss of energy?
......no! since the kinetic energy is stored in the form of potential
and all the so stored particles join to form cloud of dust which again leads to a new galaxy

.......................................as per BIG BANG theory

Answer 7

law of conservation is the language of science.otherwise no relation can be correct, anything hypothetical can be written.