# Thread: What is energy? and a gravity question related to matter...

1. ## What is energy? and a gravity question related to matter...

Einstein once said that "matter is frozen energy". His famous equation shows the equivalence of matter and energy. The standard model of Quantum Mechanics is all particle-based. The fermions compose matter, the bosons are the carriers of forces. We usually envision the one as particle-like and the other as wave-like, yet the models have been shown to be interchangeable. What is a wave, actually? Just a mathematical equation with no substance, describing the propagation/probability of matter/energy?

The Big Bang started out as pure energy, and only as it cooled down, did particles appear.

Hard to understand what energy is. We only have working models for it. Same goes for matter.

If a particle travels past a black hole, it will seem to an outside observer that it is being accelerated and time dilation occurs and ultimately stops the image at the event horizion as the particle falls into the black hole. Gravity is not covered by Quantum Mechanics and is considered as being only a spatial distortion so it does not represent energy, yet it can "speed up" an object, seemingly giving it more energy. The acceleration is an illusion and the object is following a spatial distortion. Is this correct?

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Originally Posted by gzhpcu
Einstein once said that "matter is frozen energy". His famous equation shows the equivalence of matter and energy. The standard model of Quantum Mechanics is all particle-based. The fermions compose matter, the bosons are the carriers of forces. We usually envision the one as particle-like and the other as wave-like, yet the models have been shown to be interchangeable. What is a wave, actually? Just a mathematical equation with no substance, describing the propagation/probability of matter/energy?

The Big Bang started out as pure energy, and only as it cooled down, did particles appear.

Hard to understand what energy is. We only have working models for it. Same goes for matter.

If a particle travels past a black hole, it will seem to an outside observer that it is being accelerated and time dilation occurs and ultimately stops the image at the event horizion as the particle falls into the black hole. Gravity is not covered by Quantum Mechanics and is considered as being only a spatial distortion so it does not represent energy, yet it can "speed up" an object, seemingly giving it more energy. The acceleration is an illusion and the object is following a spatial distortion. Is this correct?
I can definitely give one infinitesimally, small part of an answer to your question(!) A big connection between energy and matter is the (in my very loosely based argument) the field aspect---> gravity based on matter has field component . . . although gravity waves may not have been directly observed (and their existence and exact nature(?) will be subject to debate). Waves do exist in my frame of mind--not just as a mathematical abstraction--but from evidence of sound impinging upon the ear-drum to sun's light upon chlorophyll. This is an anthropocentric view of the world around me ---the fact of changes in my own surroundings tells me that I can rely upon an abstract description of the matter, waves, energy, bosons, fermions, . . .

_________________________
Experimental results always precede theory

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You would most probably find this post very interesting . . . you might have to skip past the ahhhhs and ummmms of the first 8 or so minutes if you have to?

4. Originally Posted by gzhpcu
The Big Bang started out as pure energy, and only as it cooled down, did particles appear.
I'd disagree with that. I don't think there's any such thing as "pure" energy. Energy is a property that particles have, not a thing in and of itself. In the earliest epoch of the universe, before it had cooled down, it's not that there were no particles, it's just that all the particles there were had sufficient energy and interacted frequently enough that they were constantly transforming into other particles (including lots of photons). But I don't think you can have energy devoid of particles. Sometimes we think of light as "pure energy", but it's not. Energy is a property that light has, along with other properties as well, and that's true whether we view light as an electromagnetic wave or as individual photons.

Originally Posted by gzhpcu
Hard to understand what energy is. We only have working models for it. Same goes for matter.
But that's pretty much true of everything. All of science is pretty much just a big working model of how the universe works. Whether the underlying reality is something like our model is a matter of some debate. Some would contend that talking about what the universe is "really" like isn't even a sensible question.

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Originally Posted by Grey
I'd disagree with that. I don't think there's any such thing as "pure" energy. Energy is a property that particles have, not a thing in and of itself. In the earliest epoch of the universe, before it had cooled down, it's not that there were no particles, it's just that all the particles there were had sufficient energy and interacted frequently enough that they were constantly transforming into other particles (including lots of photons). But I don't think you can have energy devoid of particles. Sometimes we think of light as "pure energy", but it's not. Energy is a property that light has, along with other properties as well, and that's true whether we view light as an electromagnetic wave or as individual photons.

But that's pretty much true of everything. All of science is pretty much just a big working model of how the universe works. Whether the underlying reality is something like our model is a matter of some debate. Some would contend that talking about what the universe is "really" like isn't even a sensible question.
Grey:
You have hit upon an "excellent" point----->actions will always outpace words . . .
The current paradigm of science makes it enjoyable to those who practice it . . . whether it's some model through computation or experimentation.

If I never knew how to question my surroundings and tried to understand nature . . . I would find life very boring

6. Originally Posted by Grey
I'd disagree with that. I don't think there's any such thing as "pure" energy. Energy is a property that particles have, not a thing in and of itself. In the earliest epoch of the universe, before it had cooled down, it's not that there were no particles, it's just that all the particles there were had sufficient energy and interacted frequently enough that they were constantly transforming into other particles (including lots of photons).
Yes, right. Energy is represented by boson particles. I had meant to say matter.
Originally Posted by Grey
But that's pretty much true of everything. All of science is pretty much just a big working model of how the universe works. Whether the underlying reality is something like our model is a matter of some debate. Some would contend that talking about what the universe is "really" like isn't even a sensible question.
It may not be "sensible", but it is fascinating.

7. Originally Posted by gzhpcu
Yes, right. Energy is represented by boson particles. I had meant to say matter.
Nah, both bosons and fermions existed in the early universe. Some have no rest mass, others do, but in the very early universe, they were changing back and forth and interacting with each other so frequently, that it was nothing like the sedate state today, where you have more or less stable particles of matter forming complicated structures.

Originally Posted by gzhpcu
It may not be "sensible", but it is fascinating.
Oh, I agree. I'm not even one of the ones who would say that talking about reality isn't sensible.

8. And I am one of the ones who would say that what the universe is "really" like is indeed an insensible topic for human language. Note that's not the same thing as saying it makes no sense to talk about reality, we just have to own up to our role in attributing meaning to the term "reality". My point would be that we have no basis to imagine the attributes of a reality that is outside our ability to interact with and understand it. Understanding must be a kind of coming to terms with ourselves, with the way we think. There really isn't any other possibility, it is self-evident. However, I will agree with you that the loose language which pretends our understanding of reality has nothing to do with us, and its more precise version that allows our understanding to be seen as part of us, usually does not differ in any important way in terms of functioning in the world. It is only when you find the more probing kinds of questions that often show up on forums like this that it becomes important to notice these distinctions!

9. But this assumes there is no yet undiscovered basis that reveals we are able to interact with all attributes of reality, and that it is all within our empirical abilities, we have just been misinterpreting things on a fundamental level..

10. Originally Posted by uncommonsense
But this assumes there is no yet undiscovered basis that reveals we are able to interact with all attributes of reality, and that it is all within our empirical abilities, we have just been misinterpreting things on a fundamental level..
How would we ever know that we are able to interact with all attributes of reality? The problem is self-evident-- we interact with what we interact with, and we don't what we don't. Our intelligence makes sense of what it can, and treats the rest as "noise", either trying to minimize it in the experiments, or averaging over it, or not even perceiving it in the first place. There is never a way to test that we have grokked the whole enchilada, and plenty of evidence to expect that we have not, not to mention that the latter is the default expectation of any exploration.

11. In 1946, George Gamow, a Russian-born scientist, proposed that the primeval fireball, the "big bang," was an intense concentration of pure energy.

12. I'm not sure anyone should rely on that article as their basis for an understanding of either the Big Bang or its history (it seems to focus on other issues related only in pretended ways with science). I agree with Grey that the phrase "pure energy" is at best ill-defined, and at worst pseudoscientific. I have heard mention of "the temperature of the vacuum", which sounds as oxymoronic as "pure energy", but there might be ways to lend some precise physical meaning to these terms. More likely, they are not intended to be taken too seriously-- I take "pure energy" and "temperature of the vacuum" to mean simply a state that is completely described by its energy content-- the idea being that when the energy available is sufficient to generate any particle we know of while "costing" the available energy only marginally, then there's no need to monitor the history of that state, it is described simply by the distribution of particles, fields, and motion that is most likely given the energy available.

13. Originally Posted by Ken G
How would we ever know that we are able to interact with all attributes of reality?
I don't know how, nor do you, but that does not necessarily mean it isn't possible,

T
he problem is self-evident-- we interact with what we interact with, and we don't what we don't.
That is the current state of affairs, at least that is our current interpretation, but recall, the earth was once flat even though people who believed that - interacted with a spherical rotation. They simply misinterpreted their interaction.

There is never a way to test that we have grokked the whole enchilada.
I think that is a bit a priori, in that, you conclude an assumption will hold forever, while events from now into forever are outside of your ability to know.

14. Originally Posted by uncommonsense
I don't know how, nor do you, but that does not necessarily mean it isn't possible,
No, but it does mean it is an objective that is impossible to know if it has been reached. That makes it not something that science can achieve, because scientific achievements are defined by testing them.
That is the current state of affairs, at least that is our current interpretation, but recall, the earth was once flat even though people who believed that - interacted with a spherical rotation. They simply misinterpreted their interaction.
True, but you are talking about misunderstanding our interactions-- a possibility that only makes the situation worse, not better. Even if we didn't have to worry about misunderstanding our interactions, we would still only have our interactions. Now, it's true that one possible stance is that of Berkeley's idealism, which says that by definition reality is only our interactions, and nothing beyond that. But idealism is generally viewed as unconstructively radical-- most scientists avow there there is a "mind-independent reality", and our mind is merely trying to understand whatever portion of it we can both interact with, and ponder successfully. A somewhat more sophisticated view is that any reality we can study or interact with must include our minds, so is not quite independent of our minds, but that is still saying that there is reality beyond the mind's interactions with it.
I think that is a bit a priori, in that, you conclude an assumption will hold forever, while events from now into forever are outside of your ability to know.
It's not an assumption, logic alone, coupled with the defining characteristics of scientific knowledge, suffices to establish that we could never test that we understand everything. The reason is that such a test would have to look like an experiment that comes out A if we understand everything, and not A if we don't understand everything. But if we understood everything, we would already know the outcome of the experiment. Consider this dialog:
Scientist: "We now know everything."
Skeptic: "If that is a scientific assertion, it must be testable, so you must tell me an experiment that you can do which will come out A if you know everything, and not A if you don't. Can you suggest such an experiment?"
Scientist: "Let me think... how about experiment X?"
Skeptic: "Do you already know the outcome of experiment X? If so, it is not a test. If not, then you don't know everything."
The scientist is bitten by their own means of establishing truth-- it has limitations. In a way, one of the most powerful aspects of science is that in science it is an axiom that it is impossible to know you are right.

I'm reminded of a video I show intro physics students, of an astronaut dropping a hammer and a feather on the Moon. As they hit together, he is heard to utter "how about that". At which point I ask my class: is it science that the prediction is correct, or is it science that the correctness of the prediction still ellicits the reaction "how about that"?

15. By and large I agree with you, however as we both know there are some truths in science that are considered self evident and do no demand testing. Consider that there may come a day when, however so achieved, all truths will become self evident and so fundamentally obvious that they will not require scientific testing. I'm simply saying you can't rule out such a possibility. The idea of it may be contrary to current understandings of science and philosophy, but philosophy, like science, is subject to mature.

16. I'd define "pure energy" as consisting of a soup of stand-alone particles. No configurations. Does this sound reasonable?

17. Originally Posted by gzhpcu
I'd define "pure energy" as consisting of a soup of stand-alone particles. No configurations. Does this sound reasonable?
Yeah quite, depending though on one's interpretation of what energy actually is, physically if at all..

18. Originally Posted by uncommonsense
Consider that there may come a day when, however so achieved, all truths will become self evident and so fundamentally obvious that they will not require scientific testing. I'm simply saying you can't rule out such a possibility.
True enough, I can only say that such a day is a day where knowledge is characterized by something other than science-- because science just doesn't work that way. It actually sounds a lot more like days in the distant past than how I imagine the future-- so I'm not sure it would be such an advancement!
The idea of it may be contrary to current understandings of science and philosophy, but philosophy, like science, is subject to mature.
It seems like a stretch-- the leopard does not change its spots so completely!

19. Originally Posted by gzhpcu
I'd define "pure energy" as consisting of a soup of stand-alone particles. No configurations. Does this sound reasonable?
I don't know if the actual absence of internal states is really so crucial-- one might presume that at any energy scale, there should be some particle that is just "coming apart"-- and some other that is not coming apart but whose internal modes (generally configurations of other types of particles) are being tickled at that energy scale. But perhaps you are saying that given any current level of physics understanding, we will not know about such higher-scale particles, so any current physics will break down at that point and have to resort to a concept of "pure energy" as a kind of placekeeper for what is not known about any actual configurations at that scale. That I could agree with.

20. Originally Posted by gzhpcu
I'd define "pure energy" as consisting of a soup of stand-alone particles. No configurations. Does this sound reasonable?
To me, not so much. Any time you have a bunch of particles, they have a configuration, even if their energy is such that it's not a bound configuration, which I think is what you're suggesting. It's also true that if the mean energy of some group of particles is sufficiently high, then you have matter-antimatter pairs being continuously produced and destroyed, and all kinds of other interactions taking place, such that just giving the temperature or energy density is probably a better description than trying to describe what particles are present. In a sense, you could call that "pure energy", but it's sort of like the situation Ken is describing, where that term is just a placeholder because it's hard to give a better description.

I do think that it's a misnomer to talk about "pure energy" as though it were a thing all by itself, envisioning that you could have just a bunch of energy. But as far as we can tell, that's never the case. Energy is not a thing, it's a property that a thing can have. And an observer-dependent property at that.

21. Wasn't it basically radiation in the form of photons, which later some of the photons became quarks, which in turn became protons and neutrons?

22. At high enough energy, pretty much everything we know about looks a lot like a photon-- but that's just a placeholder for all the things we don't know about.

23. Originally Posted by gzhpcu
Wasn't it basically radiation in the form of photons, which later some of the photons became quarks, which in turn became protons and neutrons?
There were a lot of photons, to be sure. But at very high energies, you also have all manner of quarks, leptons, bosons and the like. And all those particles are interacting with each other, springing into existence. being annihilated, and turning into other particles constantly. It's actually only after the universe cools off a bit that those particles can no longer form, and radiation comes to dominate so heavily. At that point, they mostly annihilate and leave a universe filled with almost nothing but photons, relatively speaking. Ken's right, though, that when the particles have a high energy relative to their rest energy, they have a lot in common with photons.

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My understanding is that at high energy density, more of the energy is
in the form of more massive particles, such as hyperons, because less
massive and massless particles are not able to contain as much energy
in a given volume. Mass is the most compact form of energy.

-- Jeff, in Minneapolis

25. Originally Posted by Jeff Root
My understanding is that at high energy density, more of the energy is
in the form of more massive particles, such as hyperons, because less
massive and massless particles are not able to contain as much energy
in a given volume. Mass is the most compact form of energy.
Basically, at any temperature, you have particles whose rest mass is way less than that temperature (in mass units), and you have particles with rest mass way more than that temperature (one presumes). No matter what the temperature actually is, that will be the case. The latter class will act in a "classical" way, like the particles are there or not depending on the history of the system. The former class will act in a "pure energy" kind of way, where they are coming and going willy nilly, all act relativistically and rather similar to photons, and don't depend on the history, but rather on whatever is the most likely number for there to be of them at that temperature. There shouldn't be a tendency for the ones in that former group with larger rest masses to be more prevalent-- the rest mass is pretty irrelevant if it's much less than the temperature.
Last edited by Ken G; 2010-May-12 at 02:46 AM.

26. Originally Posted by Ken G
Basically, at any temperature, you have particles whose rest mass is way less than that temperature (in mass units), and you have particles with rest mass way more than that temperature (one presumes). No matter what the temperature actually is, that will be the case. The former class will act in a "classical" way, like the particles are there or not depending on the history of the system. The latter class will act in a "pure energy" kind of way, where they are coming and going willy nilly, all act relativistically and rather similar to photons, and don't depend on the history, but rather on whatever is the most likely number for there to be of them at that temperature. There shouldn't be a tendency for the ones in that latter group with larger rest masses to be more prevalent-- the rest mass is pretty irrelevant if it's much less than the temperature.
I think you typed this the wrong way around, yes? It's the particles with a large fraction of their total energy as rest mass that behave more or less classically, while the particles with low rest mass relative to their energy behave relativistically.

27. Originally Posted by Grey
I think you typed this the wrong way around, yes?
Yup-- swap "former" and "latter"! (I made the edit, thanks.)

28. Originally Posted by Grey
I think you typed this the wrong way around, yes? It's the particles with a large fraction of their total energy as rest mass that behave more or less classically, while the particles with low rest mass relative to their energy behave relativistically.
Which is einstein bose condensate?

29. Originally Posted by gzhpcu
Einstein once said that "matter is frozen energy". His famous equation shows the equivalence of matter and energy. The standard model of Quantum Mechanics is all particle-based. The fermions compose matter, the bosons are the carriers of forces. We usually envision the one as particle-like and the other as wave-like, yet the models have been shown to be interchangeable. What is a wave, actually? Just a mathematical equation with no substance, describing the propagation/probability of matter/energy?
Not at all, it's the essence of substance, the probability that there's some right there. Actually it's the square of the probability amplitude; which is a technical definition of the probability. The only consistent description we have is the Standard Model, which describes things with the Schroedinger Equation, or equivalently, Heisenberg's Matrix Mechanics, or Feynman's Path Integrals. The way that it says these "particle" things (which have nothing to do with the little colored balls in the high school physics books) behave is often counter-intuitive to us, because the universe as something as simple as a particle sees it doesn't have very much to do with how something as complex as a human sees it. As Feynman put it, you shouldn't ask "how can it be like that," because you'll get "down the drain" and lose track of what you're trying to do, which is figure out what it's doing, not why it's doing it.

As far as we can tell, those particles (or some of them, anyway) are the most fundamental entities in physics that we've seen so far. Some theories exist (and I'm going to stick to the mathematical definition of "theory," so stop telling me "string theory isn't a theory") that say that there are more fundamental things than quarks and leptons, and gluons and W- and Z-bosons and photons and maybe gravitons, but those are incomplete theories at this time, and only partly susceptible to test at this time as well. So when you ask "what is energy," the reply you received that said "an attribute of particles" is as accurate as any.

Originally Posted by gzhpcu
The Big Bang started out as pure energy, and only as it cooled down, did particles appear.
No. The particles were there all the time, and in fact going backwards the hotter it got the more kinds of particles, not just the more particles, there were.

Originally Posted by gzhpcu
Hard to understand what energy is. We only have working models for it. Same goes for matter.
Not really. We can see how energy can convert from an attribute of a particle into a whole other particle; most commonly, a photon, but the symmetries also imply that this should happen with gluons, and W- and Z-bosons, as well, and with gravitons if they exist (and this may have something to do with the relationship between gravitational mass and inertial mass, and with Mach's Hypothesis, as well, and therefore could also involve the perhaps more fundamental Higgs and Goldstone bosons, which we may be on the cusp of discovering at the LHC).

Originally Posted by gzhpcu
If a particle travels past a black hole, it will seem to an outside observer that it is being accelerated and time dilation occurs and ultimately stops the image at the event horizion as the particle falls into the black hole.
Errr, this is two incompatible views chopped up and mixed together in a thoroughly unsatisfying way. You need to separate things as the particle sees them as it accelerates toward the event horizon under the influence of the gravity of the black hole, things as a collection of particles sees them under the same conditions, and things as various observers see them. These views can be and often are incompatible with one another, but no paradox results because it is impossible for them ever to communicate. You should do a lot more reading about black holes before you start going here, or at least ask a lot more questions. I suggest starting with Kip Thorne's Black Holes and Time Warps and Leonard Susskind's The Black Hole War, that will get you up to speed on current thinking.

Originally Posted by gzhpcu
Gravity is not covered by Quantum Mechanics and is considered as being only a spatial distortion so it does not represent energy, yet it can "speed up" an object, seemingly giving it more energy. The acceleration is an illusion and the object is following a spatial distortion. Is this correct?
No. There is currently no quantum mechanical description of gravity, but that does not mean there never will be. Gravity does not "represent" energy, but there is gravitational potential energy in resisting gravity as there is electromagnetic potential energy in resisting the electromagnetic force, and an object that stops resisting gains kinetic energy with respect to the source of the field in both cases in a substantially mathematically identical manner. The EM force is, of course, fully quantized and second-quantized, and fully represented in a field theory, a quantum theory, and a quantum field theory.

The acceleration is not an illusion. It might be from some points of view, and those might turn out to be highly useful, but there are other equally valid points of view from which it is terrifyingly real.

30. Originally Posted by tommac
Which is einstein bose condensate?
I'm not sure what this question has to do with the situation at hand, but a Bose-Einstein condensate is a just particularly extreme case of the former. That is, very nearly all the energy a Bose-Einstein condensate possesses is in the form of rest mass, and it's in the lowest possible energy state otherwise. But the rest mass of normal matter at room temperature accounts for all but a tiny fraction of the energy of that matter, too.

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