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Offline DoctorBeaver

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What is energy?
« on: 17/06/2008 21:32:16 »
I keep hearing & reading about energetic particles, conservation of energy, high-energy colliders, E=MC2, etc & I understand what it all means; but what actually is energy?

Whatever it is, I could do with more of it!  :D


 

lyner

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What is energy?
« Reply #1 on: 18/06/2008 08:50:17 »
School definition, now and when I was a lad: "The capacity to do work"

Sounds like a cop-out but, as you can transfer energy from one form to any other and you can recognise and measure work when it happens (force times distance), it's not a bad attempt at a definition.

I don't think you need to look further than that.
 

Offline Soul Surfer

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What is energy?
« Reply #2 on: 18/06/2008 09:05:12 »
Energy is what the universe is made of. Even mass is a form of localised energy.
 

Offline LeeE

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What is energy?
« Reply #3 on: 18/06/2008 14:54:24 »
Energy is the fundimental building block of everything that exists as an independent entity.  It requires space to exist within and it requires time to act (cause change) within.

With no energy, the universe would be totally empty and purely abstract.

If there was to be no change in the universe, we could arguably do away with time.  It's arguable because if there's no time you could say that it will have never existed.

So, in a real universe where any change is to occur, you seem to need all three compenents - you can't really think meaningfully about just one in isolation.
 

lyner

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What is energy?
« Reply #4 on: 18/06/2008 15:53:38 »
This is a difficult item and I think the problem lies in history.
Long before E = Mc2, Energy was taken for granted - you collected food and fuel, used the wind to sail with and heated things up in the Sun.
In the 18thC. they had this idea that Phlogiston flowed out of 'fire' into the Air and this heated things up. (Priestly)
Once they invented Steam Engines and started to do serious measurements, it was realised that head could do work for you and Joule realised that work could be converted to heat (friction). He invented the idea of 'The mechanical Equivalent of Heat' (4.2 Joules per Calorie).
Energy became a commercial matter, the Energy content of fuels came into it and so we had Heat / Mechanical Energy / Chemical Energy.
Then up comes Electricity and, of course, it was recognised as another 'form' of energy.
By then, Energy was realised to be what made things happen when there was a transfer of it. So, by being a catch-all term, it was almost redundant because it didn't differentiate between things. All you could say was that it is responsible for changes.

Then Einstein showed that Energy and Mass were equivalent and so Energy became more or less Everything. It became too big, as a term, to be useful.

It still has its uses in education but, once you've got it as an idea, you realise that you can't say what it is.

Every time I start on the topic of Energy in School I tell 'em that I will give anyone £10 if they can tell me anything that 'happens' which doesn't involve Energy. I haven't parted with any money yet, although I sometimes have to think a bit hard.
« Last Edit: 18/06/2008 15:56:05 by sophiecentaur »
 

Offline DoctorBeaver

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What is energy?
« Reply #5 on: 18/06/2008 16:34:14 »
Thank you all. Very informative.

Every time I start on the topic of Energy in School I tell 'em that I will give anyone £10 if they can tell me anything that 'happens' which doesn't involve Energy. I haven't parted with any money yet, although I sometimes have to think a bit hard.

Dying. Can I have my £10 please  :D
 

lyner

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What is energy?
« Reply #6 on: 18/06/2008 17:50:00 »
Rotting. Worms crawling around. Bowels emptying. Church bells - need I go on. (Replaces tenner in wallet)
 

Offline TheHerbaholic

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What is energy?
« Reply #7 on: 18/06/2008 18:20:17 »
Rotting. Worms crawling around. Bowels emptying. Church bells - need I go on. (Replaces tenner in wallet)

Energy doesn't use energy, because its already energy. *holds out hand*
 

Offline LeeE

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What is energy?
« Reply #8 on: 18/06/2008 18:54:22 »
But energy certainly involves energy, which is what the bet stipulates.

The best I can come up with is something along the lines of: increasing the length of the sides of a square increases the area of that square.
 

Offline JP

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What is energy?
« Reply #9 on: 18/06/2008 19:11:40 »
But the bet also stipulates that something 'happens.'  If your square is imaginary, then nothing has 'happened.'  If your square physically exists, then forces had to be applied to move it, which involves energy. 

Time and energy are very closely linked (see http://en.wikipedia.org/wiki/Noether%27s_Theorem).  If something doesn't change in time, energy is conserved in that system.
 

Offline DoctorBeaver

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What is energy?
« Reply #10 on: 18/06/2008 20:30:14 »
Rotting. Worms crawling around. Bowels emptying. Church bells - need I go on. (Replaces tenner in wallet)

I meant the moment of death itself. The actual dying; not what happens afterwards.
 

lyner

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What is energy?
« Reply #11 on: 18/06/2008 22:14:58 »
Then it's something (life) NOT happening.
Owzat?
In any case, when you are alive, life processes are taking place - death means a different set of processes start. If you can detect when the change happens, there must be some transfer of energy.
 

Offline JP

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What is energy?
« Reply #12 on: 18/06/2008 22:28:13 »
For one thing, brain activity will drop off immediately, which means less electrical currents, and those currents carry energy...

This is pretty macabre for a physics discussion!
 

Offline DoctorBeaver

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What is energy?
« Reply #13 on: 19/06/2008 07:14:11 »
Then it's something (life) NOT happening.
Owzat?
In any case, when you are alive, life processes are taking place - death means a different set of processes start. If you can detect when the change happens, there must be some transfer of energy.

 

lyner

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What is energy?
« Reply #14 on: 19/06/2008 16:28:51 »
I love your sudokus Dr B.
I have wasted a lot of energy in that direction!
 

Offline Supercryptid

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What is energy?
« Reply #15 on: 19/06/2008 16:37:03 »
But the bet also stipulates that something 'happens.'  If your square is imaginary, then nothing has 'happened.'  If your square physically exists, then forces had to be applied to move it, which involves energy.

Even if the square is imaginary, the act of thinking about it requires energy transfer in your brain's neurons.
 

Offline DoctorBeaver

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What is energy?
« Reply #16 on: 19/06/2008 16:39:27 »
I love your sudokus Dr B.
I have wasted a lot of energy in that direction!

Thank you  [^]
 

Offline LeeE

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What is energy?
« Reply #17 on: 20/06/2008 00:52:10 »
But the bet also stipulates that something 'happens.'  If your square is imaginary, then nothing has 'happened.'  If your square physically exists, then forces had to be applied to move it, which involves energy.

Even if the square is imaginary, the act of thinking about it requires energy transfer in your brain's neurons.

The square doesn't have to be thought about by anyone - it's a universal principle regardless of whether anyone thinks about it, or not.  However, I'm reluctant to claim the prize without clarification of the definition of 'happens'.
 

Offline Alan McDougall

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What is energy?
« Reply #18 on: 22/06/2008 05:51:58 »
Hello,

"What is energy"? This is much more profound question than perhaps some of us realize.

Someone asked me if I could obtain a bottle full of the fundamental stuff than becomes what we call energy. Of course, I could not.

Energy at its most fundamental level can be described as the variation of the vibration of fundamental particles, which translated into what we call energy.

Of course, this is just my take on the matter!

All energy we utilize on our planet comes from our sun and the sun got its energy from the energy from the big bang creation event.

All the original energy produced in the creation event 15 billion years ago, has by now been dissipated by relentless "entropy" into the universe and by this process has now an average temperature of just a tad above absolute zero.

Nevertheless, all the colossal energy of the big bang is still contained in the universe, just dissipated into the void or heat sink of the universe, because energy can never be created or destroyed, it can only change from one form to the other.

Every thing that exists, has always existed, nothing new ever comes into existence. (just a quote of my own)

 

Alan
 

Offline DoctorBeaver

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What is energy?
« Reply #19 on: 22/06/2008 09:23:55 »

Every thing that exists, has always existed, nothing new ever comes into existence. (just a quote of my own)


Even The Naked Scientists!?  [:0]
 

Offline Alan McDougall

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What is energy?
« Reply #20 on: 22/06/2008 09:52:19 »
Doctor Beaver,

Quote
Even The Naked Scientists!?

 ;). I meant the elements or fundamental particle that make up your present body

When you die sort of dust-to-dust you know. The water that makes up most

of your body evaporates and eventually returns to Great Ocean from which it originally came. Ultimately everything will be separated down into elements hydrogen/Helium etc etc.

The naked scientists know this of course but I just added this little peace for interest of others.

Regards

Alan 

 
 

Offline Soul Surfer

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What is energy?
« Reply #21 on: 22/06/2008 10:13:17 »
That is just not true  in fact and probably not true in the way you are thinking about it.  It is however true in tems of energy which is conserved.  We are so familiar with matter that it is difficult to accept that it is only a relatively short lived  feature of our universe.  Something that exists in quite large quantities now during the early days of our universe but in the really long term our universe will consist of black holes slowly evaporating as long radio waves into a frigid void over periods unimaginably longer than the 14 billion or so years of time that have happened to date.

Energy becomes matter.  If a very high energy gamma ray passes close to an atom it is quite possible for the gamma ray to lose energy, the nucleus move a bit and an electron positron pair to be produced out if nothing other than the quantum mechanical vacuum.  this is matter being created out if nothing except the energy of the universe.  Look up "pair production" to understand a bit more about the process.

http://en.wikipedia.org/wiki/Pair_production

Energy is the fundamental thing in the universe.  Even space and time bend and change in response to energy.
« Last Edit: 22/06/2008 10:18:16 by Soul Surfer »
 

Offline DoctorBeaver

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What is energy?
« Reply #22 on: 22/06/2008 22:38:36 »
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black holes slowly evaporating as long radio waves into a frigid void over periods unimaginably longer than the 14 billion or so years of time that have happened to date.

Fortunately for us, that won't be until 1038 years after the BB.
 

Offline Alan McDougall

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What is energy?
« Reply #23 on: 23/06/2008 07:31:12 »
Soul Surfer and Doctor Beaver,

Soul Surfer

You said

Quote
That is just not true  in fact and probably not true in the way you are thinking about it.  It is however true in tems of energy which is conserved.  We are so familiar with matter that it is difficult to accept that it is only a relatively short lived  feature of our universe.  Something that exists in quite large quantities now during the early days of our universe but in the really long term our universe will consist of black holes slowly evaporating as long radio waves into a frigid void over periods unimaginably longer than the 14 billion or so years of time that have happened to date.

Energy becomes matter.  If a very high energy gamma ray passes close to an atom it is quite possible for the gamma ray to lose energy, the nucleus move a bit and an electron positron pair to be produced out if nothing other than the quantum mechanical vacuum.  this is matter being created out if nothing except the energy of the universe.  Look up "pair production" to understand a bit more about the process.

http://en.wikipedia.org/wiki/Pair_production

Energy is the fundamental thing in the universe.  Even space and time bend and change in response to energy

By Gamma ray loss of energy! Do you mean the inevidable decay of everything, matter, energy? matter etc at the dark end of the heat death of the universe (proton decay)? The jury is still out on this I think!

I find it hard to comprehend something being created from nothing. A trillion trillion zeroes multiplied by an infinity of zeroes still give you zero.

Of course, just because I cannot conceive of it does not mean it does not happen!

Matter stars, galaxies in the grand order of the universe might be seen as slight impurities in the unimaginable vastness of the universe,

I have heard a somewhat crude analogy of matter, that it is frozen energy.

Energy is the fundamental thing of the universe, please define "Thing"

Doctor Beaver

You posted

Quote
black holes slowly evaporating as long radio waves into a frigid void over periods unimaginably longer than the 14 billion or so years of time that have happened to date.

Doctor Beaveryou said

Quote
Fortunately for us, that won't be until 10 to per power of 38 years after big bang.

What about the below take on infinity/ eternity? ;) ;)
 
 

Empty your mind. We’re about to take a BIG leap into the future. Not just a lousy few billions of years, but 10 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 years!
One ‘googol’ years, is the official word for that number. It’s the current age of the Universe, one billion billion billion billion billion billion billion billion billion billion times over. Squeeze the entire history of our Universe into the thickness of a dollar bill, and one googol years would give you a pile of money that reaches one hundred quadrillion quadrillion quadrillion quadrillion light years high. It wouldn’t even fit in our Universe.

One googol years. That’s truly staggering. Beyond anything a human can comprehend.

First, let’s fast-forward to the not-so-awfully-far future. For the coming billions of years, scientists predict quite a ride. The Sun will explode, the Milky Way will slam into another galaxy. The Cosmos might collapse, or get torn apart -- scientists can’t seem to decide yet which is more likely. And even if the Universe doesn’t do that, we’re destined to face a weird and horrible crisis, which involves us spending our lifetime as sleeping robots.

The problem is that the Universe gets bigger and cooler. Ever since the Big Bang, it expands, much like an expanding ball of fire after an explosion. Right now, the Universe is still young. It has these cute stars and twinkling galaxies. But in the long run, that will change. Slowly but inevitably, the Universe will empty itself.

 Big Nothing: Eventually, the Universe will become a dark, sterile place
First, the galaxies will fly out of sight, beyond the horizon of what we can possibly see. Next, the stars in our own galaxy will burn out, one after the other. The only thing that will remain, is a dull graveyard of cold planets, dead suns and black holes. In about one hundred trillion years, the Milky Way will go black, astronomers expect.

And eventually, even this graveyard decays. One after the other, the dead stars and planets are eaten by black holes, or kicked out of the Milky Way by collisions. Astronomers expect that in one hundred to one thousand billion billion years, our galaxy has dissolved completely.
Time goes on. After a while (more trillions of years) something else will kick in. You’ll notice that even the very stuff nature is made of, isn’t stable.

A proton, the particle you’ll find in the core of atoms, has an average lifetime of 100 000 000 000 000 000 000 000 000 000 000 000 years. Wait long enough, and it will suddenly vanish. Poof, gone. The same goes for light particles, the so-called ‘photons’. They’re expected to last a few zero’s longer, but in the end, they too will kick the bucket, one after the other. Isn’t that just bizarre? The light will go out, literally.
The last thing that survives, are the black holes.

But in the end, they too will vanish. They will evaporate in a puff of radiation.

So there we are, at our unimaginable one googol years. Finally, the Universe is totally and utterly empty. You won’t see any light or spot any planet -- in fact, you won’t even find the tiniest speck of dust. The Universe has sterilized itself. All there is left, is emptiness, and darkness. Total oblivion. And worst of all: there’s nothing we can do to stop it. We can build fancy machines or futuristic devices all we like -- but in the end, they’ll all get kicked out of existence, when the matter they are made of simply vanishes.

So there you have it: infinity. Booooring, we must add.
But don’t sob. There’s an upside.

As the quadrillions of years pass by, something very odd should happen. In eternity, even the rarest events get a chance to occur. Weird, bizarre phenomena that only happen once in a zillion years or so, become quite normal.

For example: the nothingness should yield a few surprises. Already, physicists know that in a vacuum, there are sometimes tiny little energy ‘blobs’. Little, random fluctuations of the so-called ‘quantum vacuum’. Out of nowhere, tiny particles pop in and out of existence. But theory predicts that on very, VERY rare occasions, the fluctuations should be a bit larger. Out of nowhere, an entire atom might appear! Or hey, the vacuum may even spit out a few of them!

Think of it like the static on TV. Wait long enough, and out of the random fuzz, a recognizable image might materialize. Wait REALLY long, and one day a complete episode of The Bold And The Beautiful should accidentally show up!
 

 In the vastness of eternity, even things that are almost impossible become real. Like the sudden appearance of, say, a light green buste of Napoleon Bonaparte.

In the Universe, this should give some really surprising results. With eternity at hand, the vacuum should begin to yield all kinds of objects. Incoherent lumps of random garbage, most of the time. But on very, very rare occasions, you’ll see other objects popping into existence. The Eiffel tower. A purple camel. A golden parking garage filled with chocolate Cadillacs. Napoleon Bonaparte sitting next to Mike Tyson on top of a stack of comic books. As the googols of years pass by, it’s all there.

In the VERY, VERY, VERY long run, the vacuum will even belch up complete planets, and beautiful stars, burning and all. Theoretically the vacuum should even churn out a complete solar system one day, identical to ours, with a planet Earth inhabited by people. "In an infinite amount of time, one day, I will reappear", as physicist Katherine Freese of Michigan University once put it. "An crazy thought, but true."

One day the black nothingness should even produce a new Big Bang. Admittedly, we’ll have wait really long for it to happen. Researchers of the University of Chicago once tried to calculate it. And according to their best estimates, it should happen somewhere over the next 1 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 years. That’s a one with 1056 zero’s. You can count them, if you like.
 
 
 

 
 
PAPER LINKS:
Govert Schilling, Evolving Cosmos (Cambridge University Press, 2004)
Stephen Battersby, "The Final Unraveling of the Universe". In: New Scientist, 5 february 2005
     
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Offline DoctorBeaver

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What is energy?
« Reply #24 on: 23/06/2008 07:55:45 »
Quote
In the Universe, this should give some really surprising results. With eternity at hand, the vacuum should begin to yield all kinds of objects. Incoherent lumps of random garbage, most of the time. But on very, very rare occasions, you’ll see other objects popping into existence. The Eiffel tower. A purple camel. A golden parking garage filled with chocolate Cadillacs. Napoleon Bonaparte sitting next to Mike Tyson on top of a stack of comic books. As the googols of years pass by, it’s all there.

Just because something can happen, doesn't mean it will happen. There maybe no physical laws to prevent it, but there are also none to say that it must. A bit like Virgin trains running on time.

Quote
The last thing that survives, are the black holes.

But in the end, they too will vanish. They will evaporate in a puff of radiation.

So there we are, at our unimaginable one googol years. Finally, the Universe is totally and utterly empty.

So what happened to the puff of radiation? Where did that go?

Anyway, doesn't the law of the conservation of energy dictate that all the energy that ever was, must still be? It may be extremely thinly scattered, but it must still be there somewhere. Mustn't it?
« Last Edit: 23/06/2008 08:00:48 by DoctorBeaver »
 

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