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Is Dark Energy Just Light Energy..?

10/12/2017 8:10 PM

Well we have a lot of stars and we know that light can be used for propulsion in space with a solar sail, what if dark energy is just all the energy that the stars are producing, and black holes, and supernova's....so we have all this EM wave energy pushing against all these galaxies, which is a constant force, it has to have some effect...

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#1

Re: Is dark energy just light energy..?

10/12/2017 8:11 PM

Hey could you check my post about graphical detailing and see if you lead me in a better direction? It's just below your post.

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#2

Re: Is dark energy just light energy..?

10/12/2017 9:14 PM

I don't think so. Light has momentum, but nowhere that much.

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#3
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Re: Is dark energy just light energy..?

10/12/2017 10:03 PM

I realize it's a slight effect, but a constant force over billions of years seems like it could have a cumulative effect...and if there's nothing pushing back, well, there you have it...

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#10
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Re: Is dark energy just light energy..?

10/12/2017 10:45 PM

the key to this question came when Einstein developed his theory of general relativity. Photons of light are not technically affected by large gravitational fields; instead space and time become distorted around incredibly massive objects and the light simply follows this distorted curvature of space.

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#4

Re: Is dark energy just light energy..?

10/12/2017 10:05 PM

How do you know? Are you absolutely positive that you, "know that light can be used for propulsion in space with a solar sail"?

Or is it something else?

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#6
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Re: Is dark energy just light energy..?

10/12/2017 10:21 PM

Well I used the term "light" in the general sense, it's actually solar radiation which would encompass the entire EM spectrum, of which visible light is a part of....

..."The MESSENGER probe orbiting Mercury used light pressure on its solar panels to perform fine trajectory corrections on the way to Mercury.[24] By changing the angle of the solar panels relative to the Sun, the amount of solar radiation pressure was varied to adjust the spacecraft trajectory more delicately than possible with thrusters. Minor errors are greatly amplified by gravity assist maneuvers, so using radiation pressure to make very small corrections saved large amounts of propellant."...

https://en.wikipedia.org/wiki/Solar_sail

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#7
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Re: Is dark energy just light energy..?

10/12/2017 10:22 PM

Oh.

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#24
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Re: Is dark energy just light energy..?

10/14/2017 1:33 PM

I think that probe used solar wind which is more than radiation pressure. "The solar wind is a stream of charged particles released from the upper atmosphere of the Sun. This plasma consists of mostly electrons, protons and alpha particles with thermal energies between 1.5 and 10 keV...At a distance of more than a few solar radii from the Sun, the solar wind is supersonic and reaches speeds of 250 to 750 kilometers per second."

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#5

Re: Is dark energy just light energy..?

10/12/2017 10:19 PM

The expansion of the universe is either constant or increasing slightly. As the universe increases in size, the matter density falls off as the cube of the radius, but the radiation density falls off as the 4th power of the radius, and would not account for the constant expansion.

Here is someone who has the same idea in Physics Forum:

"I'm not a physicist nevertheless I wonder about these things so here goes:

On wikipedia I read that the universe contains:

68.3% Dark energy

26.8% Dark matter

4.9% Normal matter

But I wonder why normal (light energy) is not mentioned here. Since the beginning of the universe a lot of light energy has been emitted by the stars and the big-bang itself. This light energy must have some influence on the universe as well. Now isn't it possible that this light energy is responsible for the effects artibuted to dark energy and dark matter? Dark energy: It is know that photons can exert a pressure on objects when they are absorbed or reflected by it. This could resemble the force attributed to dark energy."

The response:

"At the present time, photons make up 0.005% of the energy density of our universe. Earlier, the photon density was much higher. The reason why it's so small right now is because radiation density falls off with expansion faster than matter density. If the universe expands so that the average distance between objects is doubled, then matter density drops to 1/8th its previous value, but radiation density drops to 1/16th its previous value. So early-on, radiation density determined pretty much everything about how our universe evolved. But it diluted rapidly, until matter became much more prominent. Now, matter is diluting further, while dark energy doesn't dilute at all, such that dark energy is becoming more prominent."

Reference:

https://www.physicsforums.com/threads/dark-matter-ligh-energy-dark-energy-also-light-energy.764541/

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#8
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Re: Is dark energy just light energy..?

10/12/2017 10:43 PM

Yes but again the radiation is still pushing full force but pushing on whatever is dissipating the flow of radiation....so if it's pushing on space then you in fact have the same effect as if the galaxies were still in a tighter group...it's pushing on something even if your measurement of radiation at your location has diminished...

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#34
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Re: Is dark energy just light energy..?

10/15/2017 4:20 PM

I think there is some confusion about the universal (Hubble) expansion. It's not the far away galaxies moving away but the space between them and us expanding. An analogy would be microbes living on a balloon that is being inflated. They are getting further apart but only because their "space" is expanding.

https://www.loc.gov/rr/scitech/mysteries/universe.html

In a Newtonian universe, motion of the galaxies and expansion of space itself would probably be indistinguishable. In an Einsteinian universe, two objects cannot have a relative velocity greater than light (motion through space). If space itself is expanding, there is a distance beyond which galaxies are receding at a speed faster than light.

https://en.wikipedia.org/wiki/Hubble_volume

I'm thinking that radiation pressure could have a minuscule effect on objects moving through space but would have no effect on the expansion of space itself.

Just my thoughts...

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#40
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Re: Is dark energy just light energy..?

10/16/2017 12:43 PM

"I think there is some confusion about the universal (Hubble) expansion. It's not the far away galaxies moving away but the space between them and us expanding. An analogy would be microbes living on a balloon that is being inflated. They are getting further apart but only because their "space" is expanding."

This is a popular (and very useful) analogy, but like all analogies, it has its limits - space is not a substance like the skin of a balloon that can be stretched. Whatever its real "substance" is, it seems to be space itself that is moving apart, but in such a way that it does not lose energy density while it expands. Pretty weird!

Einstein's cosmological constant has such properties and it is still the preferred candidate for dark energy. It seems to be just an intrinsic (negative) space-time curvature that was left over from the 'big-bang', whatever the cause of that event may be.

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#42
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Re: Is dark energy just light energy..?

10/16/2017 1:16 PM

OK I am gonna do this, and be chortled at. Suppose the ground electronic state of Hydrogen 1S1, is not really the ground state, but is only the most metastable of the states? (that we know of directly). Now further suppose that instead of n=1,2,3...

also we have n= 1/2,1/3,1/4,... how now brown cow?

These states appear to be produced when hydrogen (atoms) collide with ionized helium), so I have read, but I have not read the material on this to the extent to actually see the hard data that suggests this.

If we are looking for hydrogen (atoms) through the normal Rydberg states' lines (or Balmer lines if you prefer) and a large proportion of these atoms were actually not "home" in their "ground" state, then what?

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#9

Re: Is dark energy just light energy..?

10/12/2017 10:43 PM

May be as this universe is getting old, dark energy and the other stuff are some sort of wrinkles in the fabric of space and we should put cream on it just once in a while.

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#11

Re: Is dark energy just light energy..?

10/13/2017 2:43 AM

I think you can rule it out as being a significant factor...certainly not a dominant factor, at least all the light coming from fusion reactions.

The calculated dark energy far exceeds the (rest) mass of the universe. The energy released from fusion is just a small percentage of the mass of the resultant particle.

Anyway, if billions of years of light were building up over time, then the stars shouldn't be the brightest things we see....should be flooded with all that energetic light.

.

Also, 'light' can't be 'dark' energy.

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#12
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Re: Is dark energy just light energy..?

10/13/2017 3:33 AM

I don't know.... E = mc2 is a lot of energy, and added over the course of 14 billion years from 10 trillion stars, would be a lot...energy is neither created nor destroyed, that means all that energy is out there someplace in some form...WE could change the name from 'dark' energy to 'light' energy...which I like the sound of better anyway...So what is the total cubic meters of EM energy given off by the Sun in a year? If we're seeing light on this planet from galaxies from 14 billion years ago, that means the star radiation from those galaxies has spread throughout the entire universe.....

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#13
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Re: Is dark energy just light energy..?

10/13/2017 7:51 AM

What I am saying is:

Some portion of the hydrogen has been converted to heavier elements, but even if all of the hydrogen were converted, the mass equivalent of energy released would be much smaller than the mass remaining. That is far lower than the amount of dark energy hypothesized.

It doesn't matter how many eons it took place over.

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#26
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Re: Is dark energy just light energy..?

10/14/2017 7:42 PM

"....if billions of years of light were building up over time, .....the brightest things we see....should be flooded with all that energetic light." That's an interesting thought.

You know how heat flows to cold? How water seeks its own level? How a gas tries to fill a vacuum? Where does light dissipate to? Maybe what dark energy is, is the place other than black holes that light dissipates to. Sort of like wind flowing from a high pressure to a low pressure. When an object absorbs sunlight, it gets hot. Energy conversion. Do we really know all the forms that light energy can be converted to? Interesting.

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#14

Re: Is Dark Energy Just Light Energy..?

10/13/2017 9:24 AM

I would presume that the astrophysicists are way ahead of us on this, and have already compensated for that.

I have been reading about a new theory of hydrogen that does not stop at n=1 quantum number, but allows n=1/J where J = 2,3,4,5...

The model reproduces all the normal hydrogen Rydberg states, but also takes care of pesky spectral lines previously not explained when excited hydrogen atoms are colliding with Helium ions.

There seems to be a very large energy difference between n=1/2, etc, and normal ground state hydrogen.

The model appears to be solved and very accurate spectrally to atomic number 20 or so by now. I hate to say it, but the guys at the turn of the 20th Century don't get the final word on electronic structure of atoms.

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#15
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Re: Is Dark Energy Just Light Energy..?

10/13/2017 11:45 AM

If what you are reading is the work of Randall Mills of Brilliant Light Power, aka, Black Light Power, aka, Hydrocatalysis Inc, also Millsian inc. a healthy dose of skepticism would be prudent.

There have been promises for a couple decades of a working model but AFAIK, not even the claimed 'lower than ground state energy levels' has been reasonably demonstrated.

Additionally the criticism of the theoretical support for this idea (in a 1000 page book published by Mills) has been downright scathing....and these are well respected authorities throwing heavy shade.

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#18
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Re: Is Dark Energy Just Light Energy..?

10/13/2017 1:55 PM

I always remain skeptical to at least some extent, why else would I drop over $1000 on equipment to test electrolysis?

If I cannot find excess heat (for the matrix type chosen), it just ain't there to find.

So far, it is more a matter of keeping all the parts working at the same time, we lost a power supply during the storms of September, so most of October is wasted as well.

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#19
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Re: Is Dark Energy Just Light Energy..?

10/14/2017 6:57 AM

Presumptions are assumptions that have jumped the gun.

Be careful.

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#29
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Re: Is Dark Energy Just Light Energy..?

10/15/2017 12:23 PM

It seems to me that Quantum Physics forbids the state of "nothingness". That even a perfect vacuum of "nothing" still has something in it. To get beyond that "definition" of "nothing", and achieve true understanding, you probably need to get into philosophy and ask the question, "Why does "something" exist instead of "nothing"? There is a good website devoted to both science and philosophy called Closer To Truth, by Robert Lawrence Kuhn. Lots of interesting stuff there.

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#37
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Re: Is Dark Energy Just Light Energy..?

10/16/2017 9:10 AM

You will never find a state of nothing, the nearest you can get is Illinois.

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#38
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Re: Is Dark Energy Just Light Energy..?

10/16/2017 12:07 PM

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#44
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Re: Is Dark Energy Just Light Energy..?

10/16/2017 1:18 PM

Yeah, there are a lot of things I'll never find. And I'll probably never hear that tree falling in the forest, either (but that doesn't mean it doesn't still make a noise). We have a lot of trees in Illinois, but I can't listen to them all.

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#45
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Re: Is Dark Energy Just Light Energy..?

10/16/2017 1:21 PM

Have a good day, Dennis.

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#16

Re: Is Dark Energy Just Light Energy..?

10/13/2017 1:38 PM

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#17
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Re: Is Dark Energy Just Light Energy..?

10/13/2017 1:53 PM

Looks like a Balmer day to me (play on balmy).

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#20

Re: Is Dark Energy Just Light Energy..?

10/14/2017 7:18 AM

It looks like SE's question has not really been answered. AFAIK, radiation pressure played a very important role in the galaxy formation of the early universe and to some extent, is still doing so today.[a] However, it falls off so rapidly when you go into intergalactic space, that the effect is considered negligible there.

Add to that the fact that expansion seems to starts accelerating only a few billion years ago, when inter-cluster distances were immense, and I would say that the effect of radiation pressure on global expansion dynamics is practically nil.

Our best cosmological theories actually says that radiation has a net braking effect on global expansion, due to the gravitational effect of the radiation energy density. But it is presently also negligible (~0.1%) when compared to mass-energy effects.

-J

[a] https://academic.oup.com/mnras/article/427/1/311/1029262/The-birth-of-a-galaxy-II-The-role-of-radiation

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#22
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Re: Is Dark Energy Just Light Energy..?

10/14/2017 9:13 AM

I might also add here that as there exists no valid explanation for this perceived expansion, that nothing is off the table...

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#23
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Re: Is Dark Energy Just Light Energy..?

10/14/2017 12:29 PM

SE, I presume that you have meant 'the perceived accelerated expansion', because we have a solid theory and solid observations for the fact that the universe is expanding.

Accelerated expansion is still on less solid ground, where many ideas are still on the table. Light energy is however not quite one of those...

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#25
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Re: Is Dark Energy Just Light Energy..?

10/14/2017 3:18 PM

So do you think it is possible that gravity is deforming space and it's not actually expanding but just becoming irregular?...and this is becoming more pronounced because there is some limit between space and gravity...?

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#27
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Re: Is Dark Energy Just Light Energy..?

10/15/2017 5:01 AM

"So do you think it is possible that gravity is deforming space and it's not actually expanding but just becoming irregular?...and this is becoming more pronounced because there is some limit between space and gravity...?"

Yes but that does not explain the expansion in distance to distant galaxies that we observe. Remember, we have various methods for measuring cosmic distance, not just redshift.

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#28
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Re: Is Dark Energy Just Light Energy..?

10/15/2017 10:45 AM

Very informative as always, thanks Jorrie....I found the paper you linked to very interesting though beyond the scope of my ability to completely understand the implications chiefly because of the lack of math skills needed...I can now return to the reservation..

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#32
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Re: Is Dark Energy Just Light Energy..?

10/15/2017 2:33 PM

What is a solid theory? A play on words? If it is still a theory you must mean only that no one has yet proved it wrong with arguments of which you approve??

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#33
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Re: Is Dark Energy Just Light Energy..?

10/15/2017 3:32 PM

A solid theory? A theory that has withstood a century of efforts to dethrone it and it survived, like Einstein's general relativity.

To be sure, it says that the universe must either be contracting, or expanding, but it can't be static. Then solid evidence has shown that it is in fact expanding, so what else is left?

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#35
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Re: Is Dark Energy Just Light Energy..?

10/16/2017 7:05 AM

thank you.

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#36
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Re: Is Dark Energy Just Light Energy..?

10/16/2017 9:06 AM

Jorrie: What do you make of recent reports that so-called Doppler shifts (the red shifted light due to recession of interstellar and intergalactic objects) apparently have been strongly correlated with the shapes of galaxies, and apparently have less to do with distance in this light.

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#41
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Re: Is Dark Energy Just Light Energy..?

10/16/2017 1:06 PM

"What do you make of recent reports that so-called Doppler shifts (the red shifted light due to recession of interstellar and intergalactic objects) apparently have been strongly correlated with the shapes of galaxies, ..."

James, can you give us a relevant reference? There are many effects that seem to correlate with galaxy and cluster shapes.

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#43
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Re: Is Dark Energy Just Light Energy..?

10/16/2017 1:17 PM

Sorry for not having that, I will search for it this afternoon.

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#46
In reply to #41

Re: Is Dark Energy Just Light Energy..?

10/16/2017 2:24 PM

caltech - this one, if I read them correctly. This is not my wheelhouse.

iopscience - I thing this one definitely went sailing over my head.

Neither of these is where I saw the initial report, as I think it may have been in The Engineer - although first search gave me nothing....hmmm

maybe it was on CR4 - heck I even posted it - my memory is not long these days.

cs.unc study

ldolphin.org/tifftshift

Anyway, this is where my statements came from - surely I would never have thought such a thing up from scratch. LOL

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#30
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Re: Is Dark Energy Just Light Energy..?

10/15/2017 12:42 PM

".....due to the gravitational effect of the radiation energy density."? I know that radiation consists of both light and particles with mass, but light is massless. I know that is affected by gravity, but not that light has its own gravity. There's a big difference between having the properties of particles and actually being a particle. All radiation cannot be classified as either massless or having mass, because it includes both. I'm not sure what you're actually trying to say here.

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#31
In reply to #30

Re: Is Dark Energy Just Light Energy..?

10/15/2017 2:27 PM

According to general relativity, all forms of energy cause curvature of spacetime, which is equivalent to a gravitational field. Since light contains energy, it does create spacetime curvature.

Under everyday circumstances, it is negligible, but in the very early universe, the light energy was so concentrated that it was the dominant energy density. It did put a hefty brake on the early expansion, but its energy density diminished faster than the massive particles, so by the time that the CMB photons were released, it was no longer dominant.

This is the ultra-short answer. The long answer is really long!

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#21

Re: Is Dark Energy Just Light Energy..?

10/14/2017 7:39 AM

It's just a disturbance between the boundary of space and time. A coexisting cycle of energy.

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#39

Re: Is Dark Energy Just Light Energy..?

10/16/2017 12:16 PM

How about distance?

Distance is related to potential energy. Potential energy can convert to kinetic energy. Kinetic energy seems have an equivalency to mass.

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