Why space is expanding

An explanation for why the Universe is expanding is related to the effect of virtual particles and an anti-particle correspondent, appearing at the same time/same location and annihilating each other, thus producing energy. The effect altogether and as a whole with regards to space/time, in general resulting in the expansion of the Universe. This, in respect to the conclusions regarding dark energy and the expansion of the Universe.


Any thoughts?

Originally posted by Kashai
This, in respect to the conclusions regarding dark energy and the expansion of the Universe. Any thoughts?

The reason it's called "dark energy" is the "dark" means it's not understood. People develop possible ideas (maybe like the one you suggested perhaps?) to explain what dark energy is, and then look for evidence to support the idea. Since it's still called "dark" I take that to mean that nobody has yet found good enough proof to support any one idea about what exactly it is. The best treatise I've read on the topic is by John Baez:

What's the Energy Density of the Vacuum?

recent measurements by the Wilkinson Microwave Anisotropy Probe and many other experiments seem to be converging on a positive cosmological constant, equal to roughly 7 × 10^-27 kilograms per cubic meter. This corresponds to a positive energy density of about 6 × 10^-10 joules per cubic meter.

The reason they get a positive energy density is very interesting. Thanks to the redshifts of distant galaxies and quasars, we've known for a long time that the universe is expanding. The new data shows something surprising: this expansion is speeding up. Ordinary matter can only make the expansion slow down, since gravity attracts - at least for ordinary matter.

What can possibly make the expansion speed up, then? Well, general relativity says that if the vacuum has energy density, it must also have pressure! In fact, it must have a pressure equal to exactly -1 times its energy density, in units where the speed of light and Newton's gravitational constant equal 1. Positive energy density makes the expansion of the universe tend to slow down... but negative pressure makes the expansion tend to speed up.

That's one possible explanation of dark energy, but certainly not the only one. Nobody knows including that author, but so far, that's the best explanation I've seen, speculative as it is. We are all waiting for someone to come up with more evidence so we can stop calling it "dark" energy, and say for sure what it is, but we're not there yet.

The conclusion suggest a predominant effect related to virtual and anti-virtual particle's apearing in the same place and at the same time, thus annihilating each other. Given conservative conclusions, the universe should not be expanding at a rate we see today. Current analysis suggests a time when the spherical result of a collision between the Milky Way and the Andromeda Galaxy. Will be so isolated because of space/time expanding, we will not be able to see other galaxies.

"The reason it's called "dark energy" is the "dark" means it's not understood"

Actually it means the effect can only be verified alternate to direct observation....


You suggest this is theory can be incorect...have you any other explanations and so links please?

Any thoughts?

reply to post by Kashai

Read the wiki on dark energy. The two main hypotheses are the one I mentioned regarding the cosmological constant, and the alternate explanation related to scalar fields such as quintessence or moduli, but I think the former is the leading idea.

Here's another source:
Dark Energy FAQ

What might dark energy specifically be?

The leading candidate is the simplest one: “vacuum energy,” or the “cosmological constant.” Since we know that dark energy is pretty smooth and fairly persistent, the first guess is that it’s perfectly smooth and exactly persistent. That’s vacuum energy: a fixed amount of energy attached to every tiny region of space, unchanging from place to place or time to time. About one hundred-millionth of an erg per cubic centimeter, if you want to know the numbers.

Is vacuum energy really the same as the cosmological constant?

Yes. Don’t believe claims to the contrary. When Einstein first invented the idea, he didn’t think of it as “energy,” he thought of it as a modification of the way spacetime curvature interacted with energy. But it turns out to be precisely the same thing. (If someone doesn’t want to believe this, ask them how they would observationally distinguish the two.)

Doesn’t vacuum energy come from quantum fluctuations?

Not exactly. There are many different things that can contribute to the energy of empty space, and some of them are completely classical (nothing to do with quantum fluctuations). But in addition to whatever classical contribution the vacuum energy has, there are also quantum fluctuations on top of that. These fluctuation are very large, and that leads to the cosmological constant problem.

I quoted the part that I hope will put your idea in perspective if you are thinking of quantum fluctuations.

The source I previously provided includes quantitative measurements related to the cosmological constant and vacuum energy. While dark energy is not totally off topic to this thread, it is a slightly different topic, and quite involved, so it may deserve a thread of its own if you really want to explore it in depth.

Originally posted by Vitruvian

Originally posted by -PLB-
reply to post by Vitruvian

 

According to your line of reasoning an empty cup it not real. It only becomes real when you fill it with something. It is true that in order to measure space, we have to interact with it somehow, an thus "putting something in it". I don't see how it makes space any less real.

Not really - the cup is surely real, whether it be empty of full, but the empty space that the 'limiting' cup surrounds is surely different than the empty cup itself. It is the 'emptiness' of the cup that is not 'real, ' and it would be an absurdity to say that the empty cup isn't real (whether full or empty) when in fact that it is the only thing that is real within the context of this present discussion.

ALSO - Some here might be considering the cosmos in the same way that we consider an ocean (as do some scientists) - but they are not to be compared when it comes to this notion of space. The ocean - by definition - is full - therefore there's no emptiness in it. There's no room for it whereas the cosmos, on the other hand, is full of emptiness and is only populated by certain celestial bodies floating within it.

edit on 11-8-2012 by Vitruvian because: editing/spell

Your conceptual idea of space does not really correspond with the definition of space used by physicists. From Wikipedia:

Outer space is an even higher-quality vacuum, with the equivalent of just a few hydrogen atoms per cubic meter on average.[4] However, even if every single atom and particle could be removed from a volume, it would still not be "empty" due to vacuum fluctuations, dark energy, and other phenomena in quantum physics. In modern particle physics, the vacuum state is considered as the ground state of matter.

Space is really there. Its not just an idea. (also read Arbitrageur posts for more info)

Originally posted by -PLB-

Originally posted by Vitruvian

Originally posted by -PLB-
reply to post by Vitruvian

 

According to your line of reasoning an empty cup it not real. It only becomes real when you fill it with something. It is true that in order to measure space, we have to interact with it somehow, an thus "putting something in it". I don't see how it makes space any less real.

Not really - the cup is surely real, whether it be empty of full, but the empty space that the 'limiting' cup surrounds is surely different than the empty cup itself. It is the 'emptiness' of the cup that is not 'real, ' and it would be an absurdity to say that the empty cup isn't real (whether full or empty) when in fact that it is the only thing that is real within the context of this present discussion.

ALSO - Some here might be considering the cosmos in the same way that we consider an ocean (as do some scientists) - but they are not to be compared when it comes to this notion of space. The ocean - by definition - is full - therefore there's no emptiness in it. There's no room for it whereas the cosmos, on the other hand, is full of emptiness and is only populated by certain celestial bodies floating within it.

edit on 11-8-2012 by Vitruvian because: editing/spell

Your conceptual idea of space does not really correspond with the definition of space used by physicists. From Wikipedia:

Outer space is an even higher-quality vacuum, with the equivalent of just a few hydrogen atoms per cubic meter on average.[4] However, even if every single atom and particle could be removed from a volume, it would still not be "empty" due to vacuum fluctuations, dark energy, and other phenomena in quantum physics. In modern particle physics, the vacuum state is considered as the ground state of matter.

Space is really there. Its not just an idea. (also read Arbitrageur posts for more info)

edit on 12-8-2012 by -PLB- because: source added

why/how would all the energy need to be localized in one point to big bang,, if energy is natural/ the fundamental quality of existence/ nothingness.... if the true state of eternal universe is an infinite vacuum state,, how did the vacuum fluctuations generate the relatively massive amount of energy into the pre big bang dimensionless ball of everything nothingness?

reply to post by ImaFungi


Those are some key question physicists and cosmologists are struggling with, and I sure don't have the answers.

I do like the theory that the big bang is the result of 2 branes colliding. See en.wikipedia.org...

But my preference for a theory does not make it in any way more real.

Strange how the billions of ice particle in the oot/ort cloud don't distort any of the light photons from distant places,
every photo from any optical space telescope you care to think of is crystal clear, amazing.

It is because consciousness is expanding.

Originally posted by -PLB-
Those are some key question physicists and cosmologists are struggling with, and I sure don't have the answers.

Exactly. Some questions we don't have the answer to, and it's ok to say "I don't know". I know of three questions that we will have a hard time answering and may never answer:

-What caused the big bang? (Lots of ideas but nobody knows)
-What's beyond the observable universe? (and related, is the universe finite or infinite? relevant to this thread).
-What is the inside of a black hole really like? (singularity? Or something else?)

Some things may just be beyond our ability to make observations and confirm our ideas.

Originally posted by pikestaff
Strange how the billions of ice particle in the oot/ort cloud don't distort any of the light photons from distant places,
every photo from any optical space telescope you care to think of is crystal clear, amazing.

www.solarviews.com...

Within the cloud, comets are typically tens of millions of kilometers apart.

So these tiny comets are tens of millions of kilometers apart and you think it's strange we get a clear view between them? How much further apart would you expect them to be to get a clear view?

And what's really strange is, I don't see what your post has to do with why space is expanding. Isn't it off-topic?

Space is not expanding. Space or the void or the canvas as I like to call it came into or existed first?? If you accept the observation of time space was created space/time. God didnt create time it exists with the canvas. God appeared in spacetime and began creation as we know it. Thus the big bang and eventual retraction.

Alot of your suppositions sound very interesting if not probable. I myself was reasoning along the same lines using spirit instead of science and thought God must want to die due to never have experienceing that. So its interesting to see the same line of reasoning in different terms.

If it is true that all matter is moving further and further from other matter that explains to me at least why we are pursuing extreme levels of technological connectivity.

reply to post by -PLB-

My previous post gives (at least to me) a convincing argument.

It's the illusion of knowledge at play.

Describe to me the function of a bicycle. Of course - to illustrate this correctly, we'd have you sit in a controlled room and reconstruct a bicycle from memory. We can do the same with many familiar objects - toilets, common pulley systems, refrigerators, etc.

When studies are done on this - most people believe they have a very competent understanding of the devices they are familiar with... but their illustrations and explanations of those devices is anything but competent.

Now - you're in at least the 80 percentile group - so you are likely going to be able to give a fairly decent description of most common devices and give a reasonable explanation for them with only a few gaps in understanding evident.

We begin to confuse familiarity with understanding. We are -familiar- with the concepts of relativity. Many of us can utilize the equations without actually understanding the theory, itself. We get comfortable with expressions like "space-time" and treat them as if they were as real as the computer you're typing on.

But the problem with relativity - one that its developer was quick to note - is that it lacks mechanics. Gravity is merely understood as a relationship. We can't explain how it works. Time is another tricky concept - Quantum Mechanics and experiments in both have made the concept of a 'real' dimension of time suspect to say the least (which completely skews time travel implications so commonly backed by Relativity). And Space, while more demonstrably real, clashes with the lack of understanding in time. Distance is, ultimately, a relationship regarding the passage of time between the interaction of forces.

Linking the two is a psychological crutch. Quantum mechanics already illustrates it to be exceedingly improbable that time can be an unbroken causal chain with the integrity of a physical dimension.

With such blatantly flawed understandings of our universe - it is exceedingly arrogant to presume we can reliably discern its origins and its ultimate destination. Even predicting the very nature of it, currently, is imprudent.

The chances of the universe being a perfect sphere, and we being in the exact center of it, seems extremely slim. Therefore, we expect there to be things emitting radiation beyond this sphere. I think that answers your question of "Why do we expect to see light out there".

When you use red shift to determine distance to galaxies and relative luminosities - it's really difficult to say with any confidence how far away your target is.

One of the big problems with this argument is that the primary method of measuring distance is that it is presumed that space is expanding at a given rate - therefor a certain amount of red shift corresponds to a certain distance.

Using this to then support the idea that space is expanding is circular reasoning.

Perhaps I will have to later insert a foot into my open mouth - but under this model, one would expect there to be a gradual and predictable shift into the red spectrum. IE - we should be able to see entire infra-red galaxies before we get into galaxies that can be 'viewed' in the Extremely High Frequency band, the K band, and progressively down to the ELF spectrum.

While some of that lay well beyond our capability - I am not aware of this being the observed case. It goes from visible galaxies to the cosmic radio background. Which doesn't make sense under this model.

If you have other explanations please share them.

And that's the wrong attitude to have.

It's not: "Well, who has any better ideas?"

It's: "None of us can have a good idea."

This is part of our culture that I absolutely detest. It greatly and unnecessarily complicates pursuits of knowledge. Everyone feels the need to have and/or provide a direct and concrete answer/explanation.

Do you know how wrong most of our education is? Any clue? 90% of the stuff I was taught in school was complete bull# - over 20% of it I've discovered to be little more than dogma perpetuated by teachers who never bothered to challenge what they thought they knew or groups of text book authors who decided an honest: "This is a question we do not currently have an answer to - maybe your generation will figure it out." just wouldn't work.

Sure - some things we are taught are later overturned by completely unforeseen discoveries... but I'm talking about # that was just assumed to be true and decades later we test it and find out it was complete bollocks.

I don't fault people for not knowing. It pisses me off when they assume I'm stupid enough to buy their efforts at fabricating an explanation. Pisses me off even more when their position exploits your trust in it.

Not only is the universe expanding, but it is expanding at an ever increasing rate, faster and faster. We do not know yet why. There are several theories but none have been tested yet.

Originally posted by Aim64C
It's the illusion of knowledge at play.

...

Even predicting the very nature of it, currently, is imprudent.

I kind of miss how this relates to my post.

When you use red shift to determine distance to galaxies and relative luminosities - it's really difficult to say with any confidence how far away your target is.

One of the big problems with this argument is that the primary method of measuring distance is that it is presumed that space is expanding at a given rate - therefor a certain amount of red shift corresponds to a certain distance.

Using this to then support the idea that space is expanding is circular reasoning.

Not exactly. The assumption is that faster moving bodies have more red shift. A correlation exists between the brightness of objects and their red shift, less bright object have more red shift. It is also assumed that objects that are less bright are farther away. That leads to the logical conclusion that objects that are farther away have larger red shift and thus are moving faster. And that leads to the idea that the universe is expanding. There is no expansion in any of the assumptions.

This is not circular reasoning. One problem with these assumption are quasars, which do not seem to be in agreement with the observation that less bright objects have more red shift.

Perhaps I will have to later insert a foot into my open mouth - but under this model, one would expect there to be a gradual and predictable shift into the red spectrum. IE - we should be able to see entire infra-red galaxies before we get into galaxies that can be 'viewed' in the Extremely High Frequency band, the K band, and progressively down to the ELF spectrum.

While some of that lay well beyond our capability - I am not aware of this being the observed case. It goes from visible galaxies to the cosmic radio background. Which doesn't make sense under this model.

It depends on the maximal possible shift in frequency before objects are no longer visible. I don't know this figure by hearth and would have to look it up. If the maximal red shift is relatively small before objects are no longer visible, then your assumption that the frequency can get that low is wrong to start with.

And that's the wrong attitude to have.
...

Pisses me off even more when their position exploits your trust in it.

I completely disagree but I very little care about what attitude you like or not. I may be a bit blunt, but I think this is grossly off-topic.

reply to post by Arbitrageur


Thank you very much for your response and yes I was relating quantum fluctuations as a factor in expansion.

Originally posted by Kashai
Thank you very much for your response and yes I was relating quantum fluctuations as a factor in expansion.

You're very welcome.

Originally posted by -PLB-
One problem with these assumption are quasars, which do not seem to be in agreement with the observation that less bright objects have more red shift.

Quasars are outliers, yes. However I'm not sure I see that as much of a problem as some do.

Here's an analogy. As children grow up they tend to grow taller and there's a strong statistical correlation between height versus age, not totally unlike the correlation of brightness versus redshift.

And then there are a small number of very short adults (dwarfs) who are completely off the correlation of age versus height. If you study the reasons that dwarfs don't fit the correlation at all, you find it's a special case and no reason to dismiss the correlation. I see quasars in a similar fashion: they don't fit the correlation, but there may be good reasons for it (just like there are good reasons that dwarfs don't fit the age height correlation), and if so then it's not such a problem, therefore it's not much of a threat to the expanding space theory.

Originally posted by Aim64C
I don't fault people for not knowing. It pisses me off when they assume I'm stupid enough to buy their efforts at fabricating an explanation. Pisses me off even more when their position exploits your trust in it.

I agree with PLB this is off-topic so let's don't go off on a tangent here, but I do have a response to this. Yes my teachers though high school taught dogma which they did little to challenge, but I knew I was smarter than my teachers so I never put too much trust in them; wasn't this also the case with you?

Then when I got to college and some of my professors were as smart or smarter than I was, I found that many of them did challenge the dogma. They were still required to teach it of course, but they were allowed to point out their independent thoughts on parts of the dogma they thought were questionable or not well-supported, and they did.

I really can't say that any of this varies too much from my expectations so I'm not sure why it pisses you off. I didn't expect to see independent thinkers at high school or lower and mostly I didn't, and I did expect to see them at professor levels, and I did. If one relies on their own understanding and never assumes the teacher is correct that's one way to avoid getting mad about the teacher teaching something you don't like.

It's not: "Well, who has any better ideas?"

It's: "None of us can have a good idea."

In some cases that may be true. I gave some examples earlier where that's the case, like "what caused the big bang?" and "what's beyond the observable universe?" But there are many other cases where we can make lots of guesses and have reasons why some guesses are better than others. In those cases, it does boil down to who has any better ideas. That doesn't mean the ideas are right, but it shouldn't be prohibited to propose them and talk about them. If they aren't facts then we shouldn't sell them as such but I really don't see that with real physicists too much, though people who get their physics from media like TV documentaries may get that idea...a lot of those TV documentaries paint a very distorted picture of how certain or how speculative various ideas are, unfortunately.

What if the earth itself was bigger in the past meaning that everything on it was capable of larger sizes like dinosaurs mammoths and other know plant, animal and insect species that have been preserved as fossils

Over time the earth became small then it previously had been, meaning everything living on it could no longer be as large as before
Killing off creatures to large to continue to in habit a world that over thousands and millions of year decreased in size

This would leave behind only fossilized remains of what sizes those living things where at the time of their demise
Being turn into stone preserving them in a substance that takes the longest to atomically lose size over time

This explains the various sizes of large plants animals and insects that are found today

Originally posted by IblisLucifer
This explains the various sizes of large plants animals and insects that are found today

Did you mean to post that in this thread, or another thread? The theory of expanding space says the space between galaxies is growing larger, and that the size of the earth would be affected either not at all or insignificantly by this stretching of space.

That's not to say the size of the Earth has remained constant. The Earth is bombarded with something like 40 tons of material from space per day and in the past it's likely this figure was larger, especially in the earliest period of the solar system. So we actually have some evidence of the Earth growing very slightly larger due to this mass accretion.

Another problem with your idea is that in general, a larger planet would tend to have the opposite effect of what you describe. This may seem counter-intuitive at first but once you understand the geometry it's very logical. It happens in vertebrates for example because the cross-sectional area of bones increases with the square of the dimension and volume increases with the cube of the dimension, therefore bone strength can't keep up with mass as an animal faces a higher gravity environment. There are some ways to "cheat' on this geometry a little by making bones porous (as is the case with birds and their relatives the dinosaurs), but all else being equal a larger planet with more gravity would probably tend toward squat and stocky vertebrates, so the bones can be strong enough to handle the extra gravity. Here's a wiki link on the topic which is called Square-cube law. There is also the problem of explaining how the larger planet would have become smaller (and the fact that this contradicts the evidence we have of the very slight size increase from cosmic mass accretion).

Lastly there is a hypotheses regarding sizes of creatures in the past which has nothing to do with the size of the Earth, but instead relates to the composition of the atmosphere. Here's a link describing some research in this area:

jharrison.faculty.asu.edu...

It has been hypothesized that the giant insects of the late Paleozoic were made possible by high atmospheric oxygen levels, and that current insect body sizes are constrained by our atmospheric oxygen level of 21%. We are testing this hypothesis with multiple approaches including laboratory selection, physiological studies of the mechanisms of oxygen effects on insects, and cross-species comparative studies of tracheal system structure and function.

While that's interesting research, it's off-topic to the expanding space theory.

reply to post by Arbitrageur


Is the space in between the planets of the solar system the same kind/brand of space as between galaxies?

is the space between galaxies the same kind of space as the space outside the universe? ( i know you dont and cant know but what would you think?)

Because the galaxies at the edge of the universe which emit light in all directions emit light outwards towards and beyond the edge before that galaxy itself ever gets to travel that area,,, so where would that light be going? or when galaxies at the edge move into/create brand new space via expansion is that new space they are residing in space that was beyond them as outside the universe ,,,, or ( IIII GETTTT IT))) you have to make up the whole idea of expanding space because of this problem i am purporting because it helps to believe there was no space around the universe?

reply to post by IblisLucifer


What if everything in the universe (matter and space) were doubling every second? atleast my theory would account for expansion AND gravity.