Is energy real?

[Greylorn]

Is energy simply a meaningless term that appears at the left side of fundamental physics formulas, or is it actaully a thing or substance, sufficiently malleable that it can be transformed into the recognizable stuff of the universe? Another way to put this--- is energy real?

[EdEarl]

Put your finger into a candle flame until you know energy is real. NO DO NOT

 

What are you asking?

[ACG52]

Energy is a property of things, not a thing in itself.

[EdEarl]

The universe is composed of mass-energy + dark matter + dark energy. However, we do not know what any of these things are. Is any of it real, or is everything a hologram. For sure, nothing is as it appears. Everything we see can be sucked into a black hole, then cannot be seen.

 

[Sato]

The universe is composed of mass-energy + dark matter + dark energy. However, we do not know what any of these things are. Is any of it real, or is everything a hologram. For sure, nothing is as it appears. Everything we see can be sucked into a black hole, then cannot be seen.

 

 

You look like Dr. Susskind in your profile picture:

[ajb]

Is energy simply a meaningless term that appears at the left side of fundamental physics formulas, or is it actaully a thing or substance, sufficiently malleable that it can be transformed into the recognizable stuff of the universe? Another way to put this--- is energy real?

 

Energy is a property of a physical configuration; it is no more or no less real than say linear or angular momentum. At some level it is just some number that we can calculate, but this number is very important in how we model the world. I am not sure you can get a very clear non-mathematical description of what energy is.

 

[EdEarl]

You look like Dr. Susskind in your profile picture:

LOL, we are both old, bald and bearded. He is much smarter.

[Sato]

LOL, we are both old, bald and bearded. He is much smarter.

 

Or maybe you are Leonard Susskind.

[EdEarl]

Or maybe you are Leonard Susskind.

It is kind of you to say that, but I am not. My name is in fact, Ed Earl, and it was my name long before the movie in which Burt Reynolds played Ed Earl the sheriff.

[swansont]

Is energy simply a meaningless term that appears at the left side of fundamental physics formulas, or is it actaully a thing or substance, sufficiently malleable that it can be transformed into the recognizable stuff of the universe? Another way to put this--- is energy real?

 

No. Like may things in physics it's derived from an abstract concept but it's not a "thing" unto itself. We notice that it's a property of things because we find it useful — energy being conserved is really helpful in analyzing or predicting how things behave. Then we notice that it's conserved because (or if) the rules of physics don't change over time, so it seems to be the result of time translation symmetry.

[Brett Nortje]

Is energy simply a meaningless term that appears at the left side of fundamental physics formulas, or is it actaully a thing or substance, sufficiently malleable that it can be transformed into the recognizable stuff of the universe? Another way to put this--- is energy real?

Yes, energy is real. it bears reactions, and anything that reacts with something else is real, as well as the thing it reacts with. If the energy is used, is it not real? can it not be used? think of how a bit of energy in sugar can be used by you, and, being used, makes it real.

[studiot]

An allied question to ask is

 

Is the hole in a polo mint real?

 

Edited June 11, 2013 by studiot

[krash661]

if you remove anthropocentric,

then what is real ?

[MonDie]

Greylorn, would your question be more accurately stated as "What does the word 'energy' refer to?"

I am unsuccessfully trying to answer this. My first thought was that energy refers to a variety of states, but I'm not sure what the difference between a state function and a process function is. Internal energy (E) is apparently a state function, though.

Edited June 11, 2013 by Mondays Assignment: Die

[swansont]

I think it needs to be noted that in the OP, "real" is defined as being "a thing or substance", as opposed to asking if it's illusory (whether this is by design or poor phrasing we do not yet know). By that definition, a hole in a polo mint is not real. Some answers seem to not be using this definition.

[studiot]

I think it needs to be noted that in the OP, "real" is defined as being "a thing or substance", as opposed to asking if it's illusory (whether this is by design or poor phrasing we do not yet know). By that definition, a hole in a polo mint is not real. Some answers seem to not be using this definition.

 

So you don't like my comparison?

 

Both energy and holes are nouns.

 

Both are abstract nouns.

 

But they also have differences. There are grey areas. The noun classification is not perfect and there is some overlap between the categories.

 

Energy is definitely quantifiable.

 

I know this was posted in the classical physics section but neither 'a thing'

Humour is another abstract noun that is quantifiable, most would agree there is a lot of it in a Tom and Jerry cartoon.

 

But would it not also be possible to consider the question the province of philosophy, rather than classical physics?

Edited June 11, 2013 by studiot

[MonDie]

I think it needs to be noted that in the OP, "real" is defined as being "a thing or substance", as opposed to asking if it's illusory (whether this is by design or poor phrasing we do not yet know). By that definition, a hole in a polo mint is not real. Some answers seem to not be using this definition.

But we must know what the word energy refers to before we can determine whether the referent is a "thing" or "substance."

[ajb]

But we must know what the word energy refers to before we can determine whether the referent is a "thing" or "substance."

It is the "E" in our equations.

 

That may sound a bit flippant, but that maybe the best answer to understanding energy. It is a useful quantity that we can calculate given some configuration. We can define energy vecry clearly in theoretical physics, but it is hard to say what it is.

 

"It is important to realize that in physics today, we have no knowledge what energy is. We do not have a picture that energy comes in little blobs of a definite amount."- Richard Feynman, The Feynman Lectures on Physics (1964) Volume I, 4-1

 

Informally one can think of energy as being the capacity to do work. That is energy is needed for changes to happen.

 

So again, energy is as real as any abstractly defined quantity in physics.

[BrightQuark]

I'll have a go just for some fun:

 

Energy is real to us, because as an objective observer, we can see the effects of energy, a cooker hob turns read, ice melts on a warm surface.

 

A philosopher might say, 'energy is real because we notice it, it affects *us* in any number of ways, the sun heats out face, the glass of whiskey becomes more full as the ice cubes melt.

 

However, without an impartial observer, it exists anyway, the ice still melts, the sun is warm, even without an observer to comment on the action.

 

Energy is also potential energy (yes- physicists?), the ice cube has the potential to melt, the glacier recede, icicles to form?

 

What I'd be interested in, is what is classed as energy, is it almost any change of state from matter into light, or movement within the substance.

 

Ovid in his Metamorphosis changed humans into trees and gods into mortals, but they probably weren't subject to the laws of energy or physics, they were myths, and so wouldn't be classed as energy!

Edited June 28, 2013 by BrightQuark

[Michael Lee]

It depends on what one means by "real". David Hume would perhaps argue, according to "bundle theory", we experience the world through our senses and reality consists of bundles of features. We feel attributes of things, but not the thing by itself. He argued that "something" devoid of attributes doesn't exist or can even be conceived of. For example, suppose we take some honey, we can describe it as being sweet, sticky, amber in colour, doesn't go bad, tastes bitter to someone with jaundice, is odorless, etc., but these are features of honey as it interacts with ones senses and are not of honey itself; strip the honey of these features and there is nothing left. In other words, is anyone here able to think of something that exists that does not have positive attributes?

 

For energy, none of my senses are able to detect it directly. What are the features of energy? That which is capable of doing work? Does it "exist" in a substance? Are these scientific questions or philosophical ones?

Edited June 29, 2013 by Michael Lee

[A Tripolation]

Then we notice that it's conserved because (or if) the rules of physics don't change over time, so it seems to be the result of time translation symmetry.

 

I thought energy wasn't conserved over cosmological scales?

[swansont]

 

I thought energy wasn't conserved over cosmological scales?

 

Energy conservation in GR is a somewhat tricky proposition, but AFAIK it's because there is no single frame of reference. Conserved energy is not the same thing as invariant energy. Conservation of energy says that energy is constant in any frame of reference.

[jermy]

Yes the energy is real.For example while lifting an object we put effert (power) that is the energy.So for a particular period of time how much power we used is called the energy.

References:

http://physics.tutorvista.com/energy.html