Naked Science Forum
Non Life Sciences => Physics, Astronomy & Cosmology => Topic started by: Mr. Scientist on 30/09/2009 18:27:47
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I won't go into superfluous detail as i usually do, but i will posit two questions that should be answered by physics and physicists alike.
Does the universe have an energy?
How can the universe have an energy? I question this, because for a system to have a defined energy, there needs to be an observer. A couple of solutions can arise to the question, such as parallel universes - in this instance, there are an infinite amount of worlds, so a defined energy becomes ''less important'' when we invoke some kind of ultimate parallel universes where the line extends into infinity. It turns out from this picture, that every universe that can arise, would arise.
For the universe to have a defined energy [i.e. a specific quantity] - then according to the laws of quantum mechanics there needs to be an observer sitting outside of the realms of space and time. But no outside to the universe exists in relativity so a fundamental problem arises. Ultimately, all we can hope for at best so far, is to account for only a portion of the energy within the universe to be known within the boundaries of certainty with how much energy at a time is involved.
Moving on, a greater problem arises concerning energy. There is the frozen time problem of relativity - according to theory, there is no past nor future. There is no sucession of past into future.
There is no time but the present time(s); which encompasses everything. In the frozen time model, energy faces another problem. Since Noethers Theorem shows that time has a mathematical conjugate partener taken as energy, we find the two are co-independant.
And so imagine if we where to consider a timeless universe as adopted by many growing number of physicists, we would actually present ourselves with more problems, such as energy. To define the energy in the universe, you would almost certainly need time since time and energy are actingconjugates under the Noether Theorem; though, mind you, and not intentionally trying to complicate things, but how could anyone measure the energy of the universe because you would need to be outside of it to do so... but without adding any more to the problems, it still remains true thatneglecting time in a final theory of quantum mechanics will degrade the chances of measuring energy at levels required for quantum synthesis exploration, maybe more mathematically than so much experimentally.
In fact, the problem of time is the adaptation of the Scrodinger equation to a diffeomorphism invariant context by a quantizing equation gives the Wheeler-deWitt equation, which is an equation which governs the universe in a lifeless non-changing state, where time is essentially frozen, and the internal energy is non-changing. Everything should be best then to describe the universe which would be immutable.
But the universe does have an energy, just not one that can be well defined. Only a very small portion of this cloud will be condensed, and some of it we can observe measure in their various multi-particle systems to an approximation. But as expected, these problems concerning energy and timeare not alone. Without time, it is also contrary to our experience. Why would we seem to experience and represent something like a time if it was not in the manifold of space? Would evolution be audacious enough as to give us an experience of something so exotic it is not an extention of spaceitself, which would then imply that perhaps consciousness is not extention of space either? Consciousness and time are inexorably linked, and in many ways are the same. As i have already explained, remove time directionality, spice it up with a few negatives here and there as to allow it to notfollow a logical linear path, then our experiences in the world would be shortlived and perhaps even non-existent.
(I will recite any work required to uphold the statements made on request - or i will give a mathematical desription)
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Both are codependant, i mean... lol
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The universe has a mass.
E=MC^2
The universe has an anergy.
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Did you get my essential points?
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The thread title boils down to "Does energy exist? And to answer that, you need to define energy.
You're also thinking of time as something distinct from space when the sort of answer you're looking for requires them to be unified. The whole idea of a 'frozen' this, that or the many others is nonsensical, as by definition they would be static and unchangeable. If there is no change, there is no physics, because nothing can happen.
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In relativity you cannot treat space and time as different entities.
Tell me, why do you think i have?
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Mr S,
Your post seems to ask a lot of interesting questions. I like interesting questions about the nature of space because I have a hunch (only a hunch mind you!) that we are slightly clueless about the nature of space (I'll probably get some "heat" for even making that remark.)
Can you please try to slow down your questions/ideas enough to allow slower types, like me, to catch up and figure out where you are going? No need to if you don't want to, of course. Just a suggestion.
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I can certainly try. What parts are you finding difficult?
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The simple answer to the question could well be no. The universe as a whole does not have an energy because the positive energy of atoms and radiation that forms most of the universe we know could well be eaxtly (or almost exactly) balanced by the negative energy of the gravitiational field.
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Now to return to the rest of your long initial posting.
Firstly your comments about the need of a real external "observer" seems to suggest a basic misunderstanding of this term used in quantum mechanics and the Schrodinger cat paradox this does not imply any external intelligent or directed process it just means that events have to happen to resolve the paradox by creating the measurements needed. These events can be totally internal to the processes.
Your problems with space and time appear to come from taking ideas to their extreme limit without looking at what happens before these limits are reached space, time, acceleration, velocity and gravity are clearly related through relativity. however our understanding of what happens as limits are approached (but not necessarily reached) are far from complete and there is plenty of room for new supprises.
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Not at all.
Having an observer outside of spacetime has nothing to do with any ''intelligence'' - nor does it imply anything related to schrodingers cat.
I thought this much might have been realized. No, it implies the measurement of energy; or a specific eigenstate of the universe in this case. In order to measure the system for a well-defined energy, you require to observe the system. Much like the universe, you would need to be external of it to actually know its complete energy. It's well-understood that you cannot know the energy from within the system itself.
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We are therefore in a logical impasse unless you redefine what you mean by the term universe. This is because the term universe means the total sum of everything that exists and therefore it is impossible for anything to be "outside" the universe.
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We are therefore in a logical impasse unless you redefine what you mean by the term universe. This is because the term universe means the total sum of everything that exists and therefore it is impossible for anything to be "outside" the universe.
The universe in this context is under a Wheeler-de Witt analysis.
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Sorry I do not understand what you are saying. Please explain it to me in your own words using simple language. I will Google that topic but I feel qite strongly that in these pages you should strive to use language that is easily understandable by most people and in particular explain things where they use specialist technical terms.
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The simple answer to the question could well be no. The universe as a whole does not have an energy because the positive energy of atoms and radiation that forms most of the universe we know could well be exactly (or almost exactly) balanced by the negative energy of the gravitational field.
I like the idea of the universe adding up to zero , I had this idea as a boy believing it was a matter of matter and anti-matter but of course your idea of an energy balance is more satisfying.
such a universe could pop into existence in the same manner as particle anti-particle pairs
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I have now had a chance to look up this Wheeler De Witt equation and it appears to be a generalisation of the Hamiltonian (basic conservation laws) for a quantum universe in an unspecified number of dimensions where the wave functions are replaced by functionals over all possible spatial geometries and integrated over the entire volume of the multidimensional "space" (probably infinite and /or recursive). As such it does not and cannot have any existence outside of it own domain (as I expected) and therefore any concept of observing the universe as defined by this equation from outside is totally invalid.
This seems a reasonable way to approach this problem but rapidly involves almost insuperable mathematical problems unless gross simplifications are accepted from the start and leads to an attempt to define all possible universes in the same way that string theory gets bogged down in billions of possibilities.
These techniques have created useful insights but are losing the baby in the pacific ocean! there are I believe simpler and more tractable approaches that can be taken but I have so far been unable to find anyone who is following them
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Sorry I do not understand what you are saying. Please explain it to me in your own words using simple language. I will Google that topic but I feel qite strongly that in these pages you should strive to use language that is easily understandable by most people and in particular explain things where they use specialist technical terms.
Don't be ridiculous. I cannot pipe down on ordinary termonology. If no one understands the terminology, then you might ask for a definition of the concept spoken about.
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I am not quite sure why you have posted this reply because I have done precisely this in my reply above on 3rd oct at 14:24:50. Do you now accept what I have said there?
I am now rereading your original questions in the light of my additional studies and plan to post a more detailed reply in a day or two.
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Thank you.
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The best popular book that I know on the "tmeless" universe is "the end of time" by Bulian Barbour. This shows that time and space as an emergent property of a universe that in effect explores all possible configurations of itself and finds that certin squential possibilities are more probable and this leads to the development of universes with space time properties like our own.
This does not mean in any way that our concepts of time are invalid in our environment. The universe that we are aware of is a dynamic structure with energy and energy gradients. it is logical that the total enery of the bulk (everything that exists) could well be zerom any theoretiians suggest that our universe may have grown from a small "seed" universe and I have suggested elsewhere (new theories) how tiss might be possible
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The best popular book that I know on the "tmeless" universe is "the end of time" by Bulian Barbour. This shows that time and space as an emergent property of a universe that in effect explores all possible configurations of itself and finds that certin squential possibilities are more probable and this leads to the development of universes with space time properties like our own.
This does not mean in any way that our concepts of time are invalid in our environment. The universe that we are aware of is a dynamic structure with energy and energy gradients. it is logical that the total enery of the bulk (everything that exists) could well be zerom any theoretiians suggest that our universe may have grown from a small "seed" universe and I have suggested elsewhere (new theories) how tiss might be possible
Oh, but many scientists do think it makes our description of time invalid. Mentioned by quite a few scientists i can think of, some including Marcopolini and Smolin, just to name a few, have raised the issue of the frozen time paradox of relativity with great speculation. Some scientists have already concluded the only answer can be some illusion within the psyche. The frozen time model of relativity is but one description which relies on our experience of time to be some kind of illusion. Another one has its roots soiled in quantum mechanics.
In quantum mechanics (contrary to our experience), time does not even have a flow. As a type of illusion, geometric time does not exist, and only fundamental time persists. This means that there cannot be a flow to time, but instead, time exists for starts and stops; almost instantaneous flashes and moments. So all this stuff concerning time, seems to indicate that how we experience time, may not actually be how time exists ''out there.''
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I agree with you that space and time are a variable feature of our universe but I do not think calling it "an Illusion" implying that there are ways in which it may be possible to break the rules is a very likely probability.
If it was our universe could not be stable.
My opinion is as I have said elsewhere our universe is one of a vast number of broadly similar universes that have "evolved" from the bulk (as defined earlier) All these universes are essentially physically very small and contain a relatively small amount of energy as a seed but gain their space time and energy from the conservation of energy and angular momentum during their gravitational collapse. Each universe can seed vast numbers of new universes almost without limit like a fractal. The evolution process is favoured by others notably Lee Smolin who was probably one of the first to describe this concept in his book "Life of the Cosmos" ISBN 0 297 81727 2
The main evolutionary drive for universes is to gradually develop the physical laws to maximise the existence in time and space of a universe because that makes such universes much more probable to detect in any random selection of universes most of which would only last for very brief periods in a very small area.
I am not in favour of the concept of totally random selection of physical laws during the spontaneous symmetry breaking during initial expansion of the space time dimensions the randomness is biased in directions defined by the end products of variations in the physical laws which because of quantum mechanical uncertainty become more diffuse at high energies.
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I agree with you that space and time are a variable feature of our universe but I do not think calling it "an Illusion" implying that there are ways in which it may be possible to break the rules is a very likely probability.
If it was our universe could not be stable.
My opinion is as I have said elsewhere our universe is one of a vast number of broadly similar universes that have "evolved" from the bulk (as defined earlier) All these universes are essentially physically very small and contain a relatively small amount of energy as a seed but gain their space time and energy from the conservation of energy and angular momentum during their gravitational collapse. Each universe can seed vast numbers of new universes almost without limit like a fractal. The evolution process is favoured by others notably Lee Smolin who was probably one of the first to describe this concept in his book "Life of the Cosmos" ISBN 0 297 81727 2
The main evolutionary drive for universes is to gradually develop the physical laws to maximise the existence in time and space of a universe because that makes such universes much more probable to detect in any random selection of universes most of which would only last for very brief periods in a very small area.
I am not in favour of the concept of totally random selection of physical laws during the spontaneous symmetry breaking during initial expansion of the space time dimensions the randomness is biased in directions defined by the end products of variations in the physical laws which because of quantum mechanical uncertainty become more diffuse at high energies.
I don't really entertain multiple universes, to be quite honest. In fact, smolin recently rejected the multiverse theory, stating strongly that only one universe is ever in existence.
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http://physicsworld.com/cws/article/print/39306
He says:
1) There is only one universe. There are no others, nor is there anything isomorphic to it.
2) All that is real is real in a moment, which is a succession of moments. Anything that is true is true of the present moment.
3) Everything that is real in a moment is a process of change leading to the next or future moments. Anything that is true is then a feature of a process in this process causing or implying future moments.
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I do not disagree with your quotation. This does describe what happens in our universe which is the only one we will ever be able to experience and/or receive information about. The multiple universes I am talking about are entirely separated and never ever communicate with each other except that if you fall into a black hole in one you end up in a different universe for ever.
Multiverse concepts were developed to get round the problem of the extremely finely balanced nature of our physical laws in a an environment where physical laws could change as a result of the initial "set up" parameters of any particular big bang type universe.
My hypothesis is that like the ecosystems on this planet the physical laws have evolved through many generations of universes to be closely similar to those we see today in our universe because any universe seeds other universes with small quantities of it own matter. gravitational collapse and the interplay of the laws of conservation of energy and angular momentum do the rest!
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I do not disagree with your quotation. This does describe what happens in our universe which is the only one we will ever be able to experience and/or receive information about. The multiple universes I am talking about are entirely separated and never ever communicate with each other except that if you fall into a black hole in one you end up in a different universe for ever.
Multiverse concepts were developed to get round the problem of the extremely finely balanced nature of our physical laws in a an environment where physical laws could change as a result of the initial "set up" parameters of any particular big bang type universe.
My hypothesis is that like the ecosystems on this planet the physical laws have evolved through many generations of universes to be closely similar to those we see today in our universe because any universe seeds other universes with small quantities of it own matter. gravitational collapse and the interplay of the laws of conservation of energy and angular momentum do the rest!
If parallel universes could not interact in any way, then there would be little point for the theories existence. In an Everett interpretation, universes are connected through actions made making the wave function collapse. Essentially, each time some kind of measurement is performed in any universe, the possibilities that may exist give rise to the birth of new universes. In this case, you could flip a coin a hundred times and create a little over 10^30 universes. In string theory, branes smashing and interacting through the gravitational force are also really big things.
If parallel universes could not give some explanation into these factors then they would just remain a superfluous detail.
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That is one way of looking at it. It just depends how one defines the term multiverse or multiple universe and the particular theory of everything that one favours. We will have to agree to differ on this one.
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In what sense should we leave this?
If the parallel universes in your theory do not interact in any way, does this not make the extra universes a superfluous detail?
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Awh, what a base discussion we have here :)
Consider light, size-less, distance-less, timeless so ethereal yet so real and always 'interacting' with Spacetime. The difficulty with it is if we should see it as a 'one way (interaction:)' or a two way. As I like to consider light to be one more of our possible 'singularities' I would like it to only have a 'one way' information arrow but as we define it as having both sources and sinks one can discuss that. Still if 'photons' are the 'smallest' instigators of 'change' inside Spacetime the possible 'multiple universes' will be limitless if you see my drift here :)
Then again, as I also see what we call 'photons' as immaterial rifts in spacetime 'localized/defined' by all thingies 'interacting' (the impact if you will:)for our 'multiple universes' we might need to 'step up' in size to find processes existing definable by us as 'existing' when we look away too. So that leaves 'particles/invariant mass' perhaps?
But those seems also to be 'shimmering objects' at a Quantum mechanic level? So where exactly are those divergent spacetime 'paths' thought to happen. If we allow spacetime to be a 'elastic whole' as described by Einstein and also admit to it being impossible to define any particle with absolute certainty as being 'there' at a QM level?
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Two-way interaction, as in time?
Then it would need to be so. Particles do not act alone in a causal manner. Particles with an angular momentum in the fermion family have alone a spin up and spin down. They also have a spoin sidewards, and in computer-terminology, these are called quibits.
Virtual particles violate the law of directionality all the time. They flow within negative values of time, and so oscillte throughout space and time.
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Two-way interaction, as in time?
That's one of the problems :)
I differ between 'no way' (virtual particles/photons), 'two way' (quantum mechanical processes) and 'one way' (Spacetimes arrow of time).
But that's time, then I also discuss 'information flows' the same way, as having a one way flow (Black holes, entanglements, possibly tunneling too) or a two way flow as inside Spacetime mediated by f.ex. us talking, sending information electronically etc and what I would call 'no way information' relating to something undifferentiated existing as a 'whole' without any information-/time-arrow to it. But I'm not sure they work the same?
Consider if I was right in assuming that photons won't exist and that the only things we 'observe' is rifts in Spacetime as it wants to close them. Would I then be able to state that this is a 'communication'? I mean, it should be? But there is nothing there 'communicating' even though we have both a source (sun)as well as a sink (eye) receiving it?
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We are already reasonably well aware of things in our own universe that have zero or very limited communication with our own visible universe.
Firstly black holes where outgoing communication is limited to hawking radiation. Note high energy radiation from in falling matter does not count because that all occurs outside the event horizon.
Secondly if you subscribe to inflationary cosmology there is a vast area of our own universe with which we will never ever be able to communicate because the expansion means that it is receding from us faster than the velocity of light.
The fact that there could be a indefinite number of universes "out there" is unobservable but may be perfectly predictable by the final theory of everything. You seem to be thinking in a very restricted way and are probably yearning for some weird possibility of communicating with other universes though wormholes or other silly non causal ideas. Cosmology and quantum theory is weird enough without pushing the limits in this way
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Interesting Soulsurfer.
Now, I liked hawking's idea better before he changed his mind and defined it as 'interacting with Spacetime'. I don't agree to that one by several reasons. The simplest one being that you won't have a singularity any more if that is correct. Also it disturbs my own ideas :) as I then would have to redefine what singularities should be as well as information obeying lights speed in a vacuum. That if we still trust a Black Hole to be an 'infinity'.
As for your other definition of inflationary cosmology to define limits for two way flows of information you might be right, but there is no singularity defined there as it more relates to a 'no way' flow than a 'one way' flow as I defines a singularity here.
And no matter how vast the 'distances' may seem there is only one 'Spacetime' to me. Otherwise you might consider two points just out of reach, information wise, from each other. then I move one point a little closer to the other and then the other a a little further away to keep them incommunicado. I can do this a infinite amount of times which then would create 'infinite amount of universes' incommunicado with each other but still visited by you as one of those 'points' if you get my drift here. That proofs to me that there is only one Spacetime even if we might not be able to communicate with all of it.
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And so now, i'm going to talk about another strange prediction behind the mathematics of quantum mechanics. Due to conservation laws, more notably the eternal sea of energy which exists not only in a Dirac Model, where particles like electrons arise from a negative value of energy within the vacuum of spacetime called the Dirac Sea, but also in a more modern approach, one invites the existence of the zero-point energy field, which is also a negative sea of energy which counteracts every positive (and real) peice of energy in the vacuum.
It's not just a sea of negative energy - its also a sea of particles which make this potential energy. In theory, corresponded to every real positive valued particle in the vacuum has a negative virtual particle within the vacuum which mathematically renormalizes it to zero. Mathematically, we call the energy of the entire makeup from a Hamiltonian expression of the energy-mass equivalance, restated as E= \pm Mc^2 - which is of course, energy equals not only a positive energy but also a negative energy. We may call the two expressions as two solutions given as Mc^2 and -Mc^2. Mathematically, adding the two together yields absolutely nothing! This means that mathematically, physicists have been aware that when you add the energy in the observable vacuum with a corresponding energy within the potential vacuum, and then you can caculate the energy of the whole universe; and it appears to come to a big fat zero.
So does the universe have an energy? Maybe according to the first lot of work i gave you, there are questions as to how quantum mechanics may manifest an energy description with so many ordeals... but here, just above, a difference can be evaluated. We say that every bit of positive energy can be cancelled out by some bit of negative energy within the vacuum; but there is an infinite amount of this negative energy, so in effect, we rid one, only to retain a massive amount of the other.
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Surely that's the result of basic gravitational collapse to a "singularity" gravitational field energy appears in the equations as negative energy which is released as positive energy as things fall inot it and increase the negative enrtgy in the field on contraction to a mathematical singularity this will increase without limit.
There must be some sort of limiting process that restores a sensible equilibrium.
Evolutionary cosmology is a pair of my preferred ideas from a set of alternatives that I have generated that would avoid this problem.
You appear to be searching for a staisis and arguing that our universe should not exist by the "laws" of quantum mechanics. Our univere does exist so therefore these laws, or your understanding of them must be wrong.
Why not stop beating your head on an impossibility and complain that others have got something wrong and use your thinking powers to look for something that works!
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>Does the universe have an energy?
If you mean is the value of the total energy of the universe non-zero then nobody knows. Perhaps it is zero. I suspect that it is but can’t say for sure. If you mean is the large scale average energy density of the universe non-zero then no.
>How can the universe have an energy?
I don’t understand the question. To me that’s like asking “How can the Earth have mass?”
> I question this, because for a system to have a defined energy, there needs to be an
> observer.
If it were true then one cannot say that energy existed before observers existed and I disagree with that assertion. It is my opinion that the universe existed before man did.
>For the universe to have a defined energy [i.e. a specific quantity] - then according to
>the laws of quantum mechanics there needs to be an observer sitting outside of the
>realms of space and time.
This is one of those fuzzy areas of quantum mechanics. One who is well versed in the philosophy of quantum mechanics is in a better position to address your concerns. Two interesting articles on the subject are
Quantum Mechanics and Reality, by Bryce S. DeWitt, Physics Today, Sept. 1970 pages 30-35
Quantum Mechanics Needs No ‘Interpretation’ by Christopher A. Fuchs and Asher Peres, Physics Today, March 2000, pages 70-71
Otherwise I’ll take a shot at it – In my humble opinion an observer doesn’t need to be a conscious person. E.g. in Young’s double slit experiment one can consider the screen to be the observer. A collision of a photon on the screen can be considered an observation. In the first article referenced above DeWitt comments as follows in the first section of the article which is labeled Quantum Theory of Measurement
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In the simples form the quantum theory of measurement considers a world composed of just two dynamical systems, a system and an apparatus. Both are subject to quantum mechanical laws, and hence one may form a combined state vector that can be expanded in terms of an orthonormal set of basis vectors ….
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> But no outside to the universe exists…
So why can’t the observer be part of the universe? This is how it works in quantum mechanics where an observation is considered to be an interaction between different parts of a quantum mechanical system.
> in relativity so a fundamental problem arises.
In relativity the problem is not so much a conscious person as an observer. In fact in relativity an observer is defined as a coordinate system/frame of reference. And no person is required in order for such a frame to exist.
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>Does the universe have an energy?
If you mean is the value of the total energy of the universe non-zero then nobody knows. Perhaps it is zero. I suspect that it is but can’t say for sure. If you mean is the large scale average energy density of the universe non-zero then no.
>How can the universe have an energy?
I don’t understand the question. To me that’s like asking “How can the Earth have mass?”
> I question this, because for a system to have a defined energy, there needs to be an
> observer.
If it were true then one cannot say that energy existed before observers existed and I disagree with that assertion. It is my opinion that the universe existed before man did.
>For the universe to have a defined energy [i.e. a specific quantity] - then according to
>the laws of quantum mechanics there needs to be an observer sitting outside of the
>realms of space and time.
This is one of those fuzzy areas of quantum mechanics. One who is well versed in the philosophy of quantum mechanics is in a better position to address your concerns. Two interesting articles on the subject are
Quantum Mechanics and Reality, by Bryce S. DeWitt, Physics Today, Sept. 1970 pages 30-35
Let me explain the bolded part:
How can the universe have an energy?
I am probably being dramatic in the sense of my words. Essentially, the question is true. Energy in virtual superpositioned state (as you might understand from quantum mechanics) means that this virtual energy can come in the form of superpostioned states smeared over spacetime probabilistically.
This doesn't mean the energy we see everyday; this energy we see is in the form of real energy and real matter. The potential words of statistical probabilties run rife, but we don't see it. In a sense, measurement of energy in physics is essentailly important. If you study the energy eigenstate of a Hamltonian, you will find that observables are involved, and energy which has not been perturbed by measurement can remain in a ghostly superpositioned state.
In the very early universe, energy was not very well-defined. The question in the heading now changes, into how can the universe have a defined set energy? This is a truer statement because a large chunk of all the matter and energy in the universe must not b very well defined. Only a portion of the matter and energy we can observe (which covers only 1% of all spacetime) is the only small cloud of particles which have managed to decohere.
So - how can the universe have a defined energy is now backed up with why someone would need to be outside of spacetime to measure an energy, as much as energy appears as an observable in mathematics. The energy is undefined due to wave mechanics until such a resolution is transpired.
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This doesn't mean the energy we see everyday; this energy we see is in the form of real energy and real matter. The potential words of statistical probabilties run rife, but we don't see it. In a sense, measurement of energy in physics is essentailly important. If you study the energy eigenstate of a Hamltonian, you will find that observables are involved, and energy which has not been perturbed by measurement can remain in a ghostly superpositioned state.
We accept super position that solidifies into some reality at the time of observation as real now, almost without question. However we should question this every time we see it. We should question it because there is absolutely no experimental evidence that it is so. It is part of the magic you must accept if you consider Quantum Physics as representing reality.
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'Sup dudes and dudettes. [O8)]
I was trawling the web, looking for a site explaining (in more accessable terms than wiki-wackymath-pedia) how large astronomical distances are measured, when this site, and this debate, caught my eye. I hope I can contribute something worthwhile to it!
I've read through most of the posts concerning your 1st question, Mr Scientist, and I'd like to jump straight to it. I'm not entirely sure what you mean by 'does the universe have energy?' as there are conflicting answers depending on the aspect of the question you emphasise in different posts.
If you mean 'Is energy a property of the universe?' I'd say yes. Energy is the potential an object has to do work. As there exist paths the object can move along in the universe (by observation), and as there exist position-dependent forces (by observation), by E = ∫ F(x) dx energy exists insofar as it can be assigned a value. I'm not sure how much experience you have with calculus and path integrals; that equation's the first thought that popped into my mind!
However, if you mean 'Is the total energy of the universe zero?' I'd say no.
E^2 = (p^2)*(c^2) + (m^2)*(c^4)
The total momentum of the universe is zero, because it must be a constant (it's conserved) and we haven't yet observed any preferred direction to the universe. The total mass of the universe is positive* as we haven't observed negative mass; thus the total energy must be non-zero. You've mentioned virtual particles previously. Bear in mind that 'virtual' implies we cannot observe them, and that they suck the energy equivalent of their mass out of the ground energy state, adding nothing to the actual mass of the universe.
Yet again, if you mean 'Can I measure/observe/decohere all energy states in the universe from inside it?' I don't see why not, in principle. Measure almost every particle in the universe yourself; get a friend to measure those making up you. Having an observer making a 'time' measurement, though, would immediately muck up your data due to the energy-time uncertainty principle. I'm afraid going into a detailed discussion of what a 'time' measurement is would require at least a degree in physics and several reams of text; pretend you're measuring the position of every particle instead and that an observer mucks it up with a momentum measurement, allowing you to picture the effect of the space-momentum uncertainty principle.
Variance(x) * Variance(p) > 0
Incidentally, you'll never know the exact value anyways (for x and E, for the universe and each particle) as the variances cannot be 0. Each particle wavefunction will probably intermix and form superpositions straightaway anyway if you do these kinda measurements on a large scale, as gravity becomes important. No-one knows how 'fast' this happens, or what role gravity plays exactly, because as far as quantum mechanics is concerned time is a background upon which events play themselves (it's not an observable) and gravity doesn't exist!
If you find an answer to that, let me know [;)]
*Some theories posit that dark energy, the thing causing the expansion of the universe, may correspond to negative mass, but at the moment they're unproven and are thus speculative at best.
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Nice description mr homely :)
And I believe Pmb to be on the spot saying that everything in SpaceTime, with the exception of what I deem as 'singularities' a. k. a. one-way communication, to be just that, ah, observers 'interacting'. But as I'm not sure what this 'energy' refers to I won't dare to have an opinion, although I will just the same :)
Energy is what we observe 'doing work' as I understands it. We do that 'work' by manipulating what I see as SpaceTimes equilibrium. Do SpaceTime loose anything as we do so? Well, if we define it as a 'closed system' it shouldn't, do you agree? It should only 'transform' right? So no, I don't think SpaceTime loses any 'energy'. Perhaps one could see SpaceTime as our new shiny toybox with a lot of fun stuff in it. As we use the toys they become 'used' not new any more, and their batteries transforms becoming unusable for 'winding' up our toys. But we define 'energy' as some extraneous quality here it seems to me, and I'm not sure that this is the same as 'transformations'?
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'Sup dudes and dudettes. [O8)]
I was trawling the web, looking for a site explaining (in more accessable terms than wiki-wackymath-pedia) how large astronomical distances are measured, when this site, and this debate, caught my eye. I hope I can contribute something worthwhile to it!
I've read through most of the posts concerning your 1st question, Mr Scientist, and I'd like to jump straight to it. I'm not entirely sure what you mean by 'does the universe have energy?' as there are conflicting answers depending on the aspect of the question you emphasise in different posts.
If you mean 'Is energy a property of the universe?' I'd say yes. Energy is the potential an object has to do work. As there exist paths the object can move along in the universe (by observation), and as there exist position-dependent forces (by observation), by E = ∫ F(x) dx energy exists insofar as it can be assigned a value. I'm not sure how much experience you have with calculus and path integrals; that equation's the first thought that popped into my mind!
However, if you mean 'Is the total energy of the universe zero?' I'd say no.
E^2 = (p^2)*(c^2) + (m^2)*(c^4)
The total momentum of the universe is zero, because it must be a constant (it's conserved) and we haven't yet observed any preferred direction to the universe. The total mass of the universe is positive* as we haven't observed negative mass; thus the total energy must be non-zero. You've mentioned virtual particles previously. Bear in mind that 'virtual' implies we cannot observe them, and that they suck the energy equivalent of their mass out of the ground energy state, adding nothing to the actual mass of the universe.
Yet again, if you mean 'Can I measure/observe/decohere all energy states in the universe from inside it?' I don't see why not, in principle. Measure almost every particle in the universe yourself; get a friend to measure those making up you. Having an observer making a 'time' measurement, though, would immediately muck up your data due to the energy-time uncertainty principle. I'm afraid going into a detailed discussion of what a 'time' measurement is would require at least a degree in physics and several reams of text; pretend you're measuring the position of every particle instead and that an observer mucks it up with a momentum measurement, allowing you to picture the effect of the space-momentum uncertainty principle.
Variance(x) * Variance(p) > 0
Incidentally, you'll never know the exact value anyways (for x and E, for the universe and each particle) as the variances cannot be 0. Each particle wavefunction will probably intermix and form superpositions straightaway anyway if you do these kinda measurements on a large scale, as gravity becomes important. No-one knows how 'fast' this happens, or what role gravity plays exactly, because as far as quantum mechanics is concerned time is a background upon which events play themselves (it's not an observable) and gravity doesn't exist!
If you find an answer to that, let me know [;)]
*Some theories posit that dark energy, the thing causing the expansion of the universe, may correspond to negative mass, but at the moment they're unproven and are thus speculative at best.
Ahhh... but the first law of conservation is not as true as we where once told - so even if i decided to count all the particles in the vacuum in one hypothetical instant, there may be more particles or less particles the second time around.
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[quote author] But as I'm not sure what this 'energy' refers to I won't dare to have an opinion, although I will just the same :)
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My thoughts on that subject are on my website at
http://www.geocities.com/physics_world/mech/what_is_energy.htm