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Dark Energy...solved. Maybe.

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disappoint said:
I wonder if I've stumbled upon a possible explanation for dark energy?

So as you probably already know dark energy is the explanation for why the universe is expanding as opposed to collapsing. So it's the energy that works against gravity (which tends to pull things with mass together) and causes the universe to expand.

What if gravity is not just a positive attractive force? What if it can also go negative and repel?

Think about it, we live in a bipolar universe. I know it sounds crazy, well we live in a crazy universe (bad pun? 🙂)

But seriously, it's a bipolar universe. Some examples: There are no monopole magnets. There is no north without south, no positive without negative, no light without dark, good without evil, hot without cold, up without down, left without right, forward without backward. Those are the three dimensions, also time has a past and a future. If you can think of some more examples feel free to post them.

Anyway, why doesn't gravity also have a negative effect? Why would it ALWAYS be attractive? What if it's also capable of going negative. Negative gravity would have a repulsive force which would explain why the universe is expanding. You wouldn't need this kludge of dark energy.

As you may have read already, the universe does not expand where objects are gravitationally bound. In other words, you and I are not expanding along with the universe. The sun, moon, earth, this whole galaxy is not expanding, nothing in it is. What is expanding is the space between galaxies.

I propose that the space between galaxies is so devoid of mass as to have a negative gravitational effect. Repulsion. Why would gravity have to go to zero in empty space? Why not negative?

Think of gravity as the warping of space time.
gravity-probe-confirms-einstein-theories-space-time_35284_600x450.jpg



Why can't it warp upward where there is much less mass in the vicinity and not just downward?

So what do you think? Make sense?
Click to expand...

You missing the fact that the galaxies aren't being repulsed from each other to increase the space between them but the space itself is growing. Gravity acts on mass, whatever is causing expansion is acting on the fabric of space.

You have any source for expansion is only occurring in intergalactic space? From what I've heard things should expand until everything is separated.
 
Negative gravity in empty space is kinda meaningless. The point of gravity is that a large mass exerts a force on other masses. The thing about space is... it's everywhere in every direction. The net result of such gravity, whether positive or negative, would be zero, because the gravity from the space would be repelling (if negative) or pulling (if positive) from all directions at the same time equally, canceling itself out.

It's like if you could somehow stand in the very center of the earth without being ripped apart from the pressure, you wouldn't feel any gravity- the pull from the mass of the earth would pull you equally in all directions and cancel itself out.
 
Chiropteran said:
Negative gravity in empty space is kinda meaningless. The point of gravity is that a large mass exerts a force on other masses. The thing about space is... it's everywhere in every direction. The net result of such gravity, whether positive or negative, would be zero, because the gravity from the space would be repelling (if negative) or pulling (if positive) from all directions at the same time equally, canceling itself out.

It's like if you could somehow stand in the very center of the earth without being ripped apart from the pressure, you wouldn't feel any gravity- the pull from the mass of the earth would pull you equally in all directions and cancel itself out.
Click to expand...

You can't be serious. It's fairly obvious what you wrote there makes no sense. If you were serious, you must have had a temporary lapse in judgement, are confused, or misinformed.

First of all it is not the same in all directions. It only occurs between galaxies not inside them. To put it in more general terms: The expansion of space takes place between gravitationally bound objects not inside them.

This is as if you had 2 ships near each other at sea, and a massive explosion took place underwater between them causing the water to push them apart.

Except negative gravity would cause an acceleration in the expansion of space itself. The analogy of ships at sea is only to help visualize. This isn't really an explosion.

It is nothing at all like standing in the middle of the earth.

http://www.youtube.com/watch?feature=player_detailpage&v=tynGJ_TM8Sg#t=2052s

At about 34:33 Physicist Dr. Lawrence Krauss calls it gravitationally repulsive.
 
Last edited:
disappoint said:
You can't be serious. It's fairly obvious what you wrote there makes no sense. If you were serious, you must have had a temporary lapse in judgement, are confused, or misinformed.

First of all it is not the same in all directions. It only occurs between galaxies not inside them. To put it in more general terms: The expansion of space takes place between gravitationally bound objects not inside them.

This is as if you had 2 ships near each other at sea, and a massive explosion took place underwater between them causing the water to push them apart.

It is nothing at all like standing in the middle of the earth.

http://www.youtube.com/watch?feature=player_detailpage&v=tynGJ_TM8Sg#t=2052s

At about 34:33 Physicist Dr. Lawrence Krauss calls it gravitationally repulsive.
Click to expand...

Gravity needs something to act on. Whatever "thing" is being acted on by gravity is inevitably surrounded by empty space on all sides. It is the same in all directions, UNLESS there is another "thing" with mass in one direction. But guess what? If there is some object with mass, we already account for it because it is what causes gravity as we know it. Your idea is not testable, and falls into the same category as theories about god, the afterlife, ghosts, and why Activision has such a douche of a CEO.

Simply put, the physics of empty space causing negative gravity is undetectable and meaningless because there will never be any measurable force from it.
 
disappoint said:
It only occurs between galaxies not inside them.
Click to expand...

If this is true, then why am I stuck walking around on the ground. If gravity only affects large masses (ie, galaxies) then I should be floating around, not walking.

The gravity the earth exerts on me is most def. there. It's just different than the gravity the earth would exert on the moon, due to the moon's mass being much much higher than mine.
 
The biggest problem with this idea is that you would be able to measure the curvature of the universe and say it wasn't flat. We know that spacetime is curved around gravitating bodies. We also know from WMAP and Planck that the universe on large scales is not curved. If dark energy was a sort of negative gravity, we'd see an open curvature (ie, hyperbolic space), which we don't.
 
I was thinking about how the expansion of the universe is speeding up and how dark matter/energy have to be invented to make what we think we know work as we epxect it to when observing the universe one day. My thought was what if there are other big bangs also expanding into us. As the edges of the two big bangs/expanding universes get closer to one another they would speed up. Obviously if there are other, older big bangs out there beyond what we can see, because the light simply hasn't gotten to us yet, couldn't that help plug a that hole?
 
SlowSpyder said:
I was thinking about how the expansion of the universe is speeding up and how dark matter/energy have to be invented to make what we think we know work as we epxect it to when observing the universe one day. My thought was what if there are other big bangs also expanding into us. As the edges of the two big bangs/expanding universes get closer to one another they would speed up. Obviously if there are other, older big bangs out there beyond what we can see, because the light simply hasn't gotten to us yet, couldn't that help plug a that hole?
Click to expand...

If you look at the latest Planck results, you can see a "dark" area of the universe
http://arstechnica.com/science/2013...-the-universe-is-still-weird-and-interesting/
 
disappoint said:
As you may have read already, the universe does not expand where objects are gravitationally bound. In other words, you and I are not expanding along with the universe. The sun, moon, earth, this whole galaxy is not expanding, nothing in it is. What is expanding is the space between galaxies.

I propose that the space between galaxies is so devoid of mass as to have a negative gravitational effect. Repulsion. Why would gravity have to go to zero in empty space? Why not negative?
Click to expand...

Remember that expansion of the universe is happening on a cosmological time scale. While it can be observed, it is best observed at a much more macro level where the dark energy is greater than the tensor of gravity.

The expansion described is most easily measured using the red shift between galaxies and other large clusters of mass. While the theories explaining dark energy are constantly being tweaked, written, and rewritten two of the most popular focus on dark energy representation a negative vacuum energy. While not being a form of gravity that repulses objects, it describes the repulsion mechanism in the universe that you mentioned.

While we are not physically expanding along with the sun, moon, etc. our place within the expanding universe is changing. Theoretically eons in the future, the eventual expansion of the universe will progress where the negative vacuum energy will be greater than the effect of gravity and massive objects will no longer form. Energy will dissipate into the ever expanding void making the future universe a dark, cold, and boring place.

Enjoyed reading the post.
 
disappoint said:
I wonder if I've stumbled upon a possible explanation for dark energy?

So as you probably already know dark energy is the explanation for why the universe is expanding as opposed to collapsing. So it's the energy that works against gravity (which tends to pull things with mass together) and causes the universe to expand.

What if gravity is not just a positive attractive force? What if it can also go negative and repel?

Think about it, we live in a bipolar universe. I know it sounds crazy, well we live in a crazy universe (bad pun? 🙂)

But seriously, it's a bipolar universe. Some examples: There are no monopole magnets. There is no north without south, no positive without negative, no light without dark, good without evil, hot without cold, up without down, left without right, forward without backward. Those are the three dimensions, also time has a past and a future. If you can think of some more examples feel free to post them.

Anyway, why doesn't gravity also have a negative effect? Why would it ALWAYS be attractive? What if it's also capable of going negative. Negative gravity would have a repulsive force which would explain why the universe is expanding. You wouldn't need this kludge of dark energy.

As you may have read already, the universe does not expand where objects are gravitationally bound. In other words, you and I are not expanding along with the universe. The sun, moon, earth, this whole galaxy is not expanding, nothing in it is. What is expanding is the space between galaxies.

I propose that the space between galaxies is so devoid of mass as to have a negative gravitational effect. Repulsion. Why would gravity have to go to zero in empty space? Why not negative?

Think of gravity as the warping of space time.
gravity-probe-confirms-einstein-theories-space-time_35284_600x450.jpg



Why can't it warp upward where there is much less mass in the vicinity and not just downward?

So what do you think? Make sense?
Click to expand...

Imagine the universe is a bottle of shaken pop. Or rather, just the top part near the neck. The Big Bang is when you twist open the pop but don't remove the top. What happens? The CO2 in the pop comes out of solution and forms bubbles due to the decrease in pressure. Our universe is shaped just like the pop and bubbles. All of the bubbles are the voids between the galaxy clusters, and all of the galaxies are the strands of pop between the bubbles. As the pressure decreases, the bubbles expand. This is our universe.

In my illustration the dark energy pushing the expanding universe is the pressure from the CO2 forming bubbles in the pop. In our universe we do not know what the CO2 is, but no one seriously thinks it has much in common with gravity.
 
lxskllr said:
I have a problem with this picture too. It simplifies the gravity well by removing most sides. When I try to picture it as a full 3D model, my brain chokes. I'd like to see the grid lines arranged so the whole thing is fully shown. I can't picture what that would look like :^/
Click to expand...

29805.jpg
 
Fritzo said:
Here's the latest thinking about repulsive gravity:

http://news.nationalgeographic.com/...y-antimatter-physics-alternate-space-science/
Click to expand...

disappoint said:
Although the first article I googled came up with something slightly different, they attribute "anti gravity" to antimatter:

http://phys.org/news/2012-01-repulsive-gravity-alternative-dark-energy.html
Click to expand...

The National Geographic article is talking about the same physicist and theory as the phys.org article I posted.

His theory is that expansion is due to antimatter. the problem with this is that we have yet to observe enough antimatter to have this effect. Our observations tell us there is a great asymmetry between antimatter and matter in the favor of matter.

So I suppose what he means then is that this particular antimatter is dark antimatter and cannot, or has not yet been observed.

So in effect he is saying, dark energy is just dark antimatter with repulsive gravitational effects. Sort of an antimatter graviton.

I can buy that. It certainly would explain expansion, still in agreement with known observations thus far, and even suggests symmetry between matter and antimatter, so it is elegant in that respect.

Btw we have yet to observe the matter equivalent to an anti-graviton the graviton itself.
 
Chiropteran said:
Gravity needs something to act on. Whatever "thing" is being acted on by gravity is inevitably surrounded by empty space on all sides. It is the same in all directions, UNLESS there is another "thing" with mass in one direction. But guess what? If there is some object with mass, we already account for it because it is what causes gravity as we know it. Your idea is not testable, and falls into the same category as theories about god, the afterlife, ghosts, and why Activision has such a douche of a CEO.

Simply put, the physics of empty space causing negative gravity is undetectable and meaningless because there will never be any measurable force from it.
Click to expand...

Actually it is testable. All we have to do is observe a graviton and it's antimatter equivalent the anti-graviton in a particle accelerator. No easy task, but possible. Peter Higgs theorized the Higgs boson which wasn't observed until just recently. What we are theorizing is the anti-graviton.

silverpig said:
The biggest problem with this idea is that you would be able to measure the curvature of the universe and say it wasn't flat. We know that spacetime is curved around gravitating bodies. We also know from WMAP and Planck that the universe on large scales is not curved. If dark energy was a sort of negative gravity, we'd see an open curvature (ie, hyperbolic space), which we don't.
Click to expand...

And now we get to the meat of the sandwich.

You bring up an excellent point. But this theorized particle the anti-graviton and it's effect anti-gravity would not make the universe curved on a large scale.

In fact, it explains why the universe is flat and not curved. Because this would counteract the curvature of space from gravity. Gravity curves space in one direction, anti-gravity curves it in the opposite direction. The two cancel each other out and you have the flat universe you observe in the WMAP and Planck data.

Remember this is the CMBR you are forming a triangle with which is presumably at the very edge of observable space, close to the beginning. You are measuring all of space not local effects. Locally it curves due to gravity and in some parts it curves due to anti-gravity. Overall the two cancel and the universe is flat.
 
disappoint said:
So in effect he is saying, dark energy is just dark antimatter with repulsive gravitational effects. Sort of an antimatter graviton.
Click to expand...

It seems unlikely (at least to me) that antiparticles could potentially be a factor in dark energy. However, what I lean towards is that the negative vacuum in space potentially as the result of another type of boson that we have not discovered as of yet. It would be similar to a gauge boson like a gluon, and have no mass. As a result it would be potentially tricky to directly observe.

Seriously good discussion. Keep it going.
 
PrototypeZ said:
It seems unlikely (at least to me) that antiparticles could potentially be a factor in dark energy. However, what I lean towards is that the negative vacuum in space potentially as the result of another type of boson that we have not discovered as of yet. It would be similar to a gauge boson like a gluon, and have no mass. As a result it would be potentially tricky to directly observe.

Seriously good discussion. Keep it going.
Click to expand...

It seems unlikely because you don't observe these particles everyday. It took a heckuva particle accelerator to uncover the Higgs Boson. The graviton and antigraviton will be even sneakier minxes to uncover.

Yes you've got it, the Graviton is theorized to be a spin 2 massless boson.
 
disappoint said:
Actually it is testable. All we have to do is observe a graviton and it's antimatter equivalent the anti-graviton in a particle accelerator. No easy task, but possible. Peter Higgs theorized the Higgs boson which wasn't observed until just recently. What we are theorizing is the anti-graviton.



And now we get to the meat of the sandwich.

You bring up an excellent point. But this theorized particle the anti-graviton and it's effect anti-gravity would not make the universe curved on a large scale.

In fact, it explains why the universe is flat and not curved. Because this would counteract the curvature of space from gravity. Gravity curves space in one direction, anti-gravity curves it in the opposite direction. The two cancel each other out and you have the flat universe you observe in the WMAP and Planck data.

Remember this is the CMBR you are forming a triangle with which is presumably at the very edge of observable space, close to the beginning. You are measuring all of space not local effects. Locally it curves due to gravity and in some parts it curves due to anti-gravity. Overall the two cancel and the universe is flat.
Click to expand...

If there is acceleration (which there is) due to anti-gravity, there would be curvature. That's what would drive the acceleration.

Secondly, if you are proposing that anti-gravity is because of anti-matter, then we could see that too. Anti-matter would likely have an equation of state similar to that of regular matter. We'd likely be able to see that in the WMAP/Planck data too.
 
silverpig said:
If there is acceleration (which there is) due to anti-gravity, there would be curvature. That's what would drive the acceleration.
Click to expand...

There would be curvature on a universal scale only if the entire universe is expanding. Gravitationally bound galaxies aren't. Objects in this galaxy aren't as red shifted as galaxies far away from us.

silverpig said:
Secondly, if you are proposing that anti-gravity is because of anti-matter, then we could see that too. Anti-matter would likely have an equation of state similar to that of regular matter. We'd likely be able to see that in the WMAP/Planck data too.
Click to expand...

We don't see gravitons nor anti-gravitons just like we didn't see Higgs Bosons until just recently. The WMAP and Planck data show a flat universe. But not at all points. At local points you can see it varies.

What if anti-gravitons don't interact with microwave radiation (the CMBR) the same as gravitons do? I mean the same magnitude?
 
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