What exactly does it mean when scientists say the universe is expanding?

Matter from the original "Big Bang" is still moving outwards.

It means it's contracting.

What exactly does it mean when scientists say the universe is expanding?

That space itself is expanding.

What exactly does it mean when scientists say the universe is expanding?
The object which we define as the universe is becoming larger. The problem with that is obviously in the definition of the universe. Does the universe include the space which "space" hasn't reached yet? Is there an "outside"?

The object which we define as the universe is becoming larger. The problem with that is obviously in the definition of the universe. Does the universe include the space which "space" hasn't reached yet? Is there an "outside"?

So how do they define this expanding space? How can tell its the space that's expanding and not just the objects moving further apart?

How would you define the universe? By the space or the objects contained within the space? Or both?

To say the universe is expanding means that, at the level of galaxies and galaxy clusters, over time all the matter in the universe tends to move further apart.

According to the Hubble law, if we look at a distant galaxy, the further away it is, the faster it is moving away from us.

How would you define the universe? By the space or the objects contained within the space? Or both?

Well I guess I was under the impression that the objects were contained within space. Aren't the two phenomenon distinct from each other?:confused:

To say the universe is expanding means that, at the level of galaxies and galaxy clusters, over time all the matter in the universe tends to move further apart.

According to the Hubble law, if we look at a distant galaxy, the further away it is, the faster it is moving away from us.

Does this apply only at the level of a galaxy? Are we moving further away from our sun?

So how do they define this expanding space? How can tell its the space that's expanding and not just the objects moving further apart?

If you're going to posit that the expansion has something to do with individual objects (like galaxies) and not space itself, then you need to ask why the observed expansion is so uniform. For example, why is it that the speed v of every distant galaxy is related to its distance from us x by v = Hx, where H is a constant that is the same for all galaxies? Another interesting observation is that seemingly, with all galaxies apparently moving away from us, we are at the centre of the expansion. Does that mean Earth is the centre of the universe after all? (Hint: physicists say no.)

How is expanding space(time) modelled? It is modelled using the best theory we have for dealing with this kind of thing: Einstein's General Theory of Relativity. The theory allows us to postulate a universal "structure" for space and time. We then go out and collect evidence to see if the model matches the facts. Current models have a number of "adjustable" parameters, which leave us free to do some adjustment when we get new data, but many many models are absolutely ruled out by the currently available evidence. Of course, physicists would like to do better than this, and show that one particular model with no free parameters is the only possible description of our universe's spacetime. They're working on that.

According to the Hubble law, if we look at a distant galaxy, the further away it is, the faster it is moving away from us.

Does this apply only at the level of a galaxy? Are we moving further away from our sun?

We are not moving further from the Sun. Theoretically, the expansion of space applies to everything, but on "small" scales, such as the scale of an individual galaxy (and certainly our solar system), the relatively small influence of the universal expansion is overwhelmed by local gravitational influences.

If you're going to posit that the expansion has something to do with individual objects (like galaxies) and not space itself, then you need to ask why the observed expansion is so uniform. For example, why is it that the speed v of every distant galaxy is related to its distance from us x by v = Hx, where H is a constant that is the same for all galaxies? Another interesting observation is that seemingly, with all galaxies apparently moving away from us, we are at the centre of the expansion. Does that mean Earth is the centre of the universe after all? (Hint: physicists say no.)

How is expanding space(time) modelled? It is modelled using the best theory we have for dealing with this kind of thing: Einstein's General Theory of Relativity. The theory allows us to postulate a universal "structure" for space and time. We then go out and collect evidence to see if the model matches the facts. Current models have a number of "adjustable" parameters, which leave us free to do some adjustment when we get new data, but many many models are absolutely ruled out by the currently available evidence. Of course, physicists would like to do better than this, and show that one particular model with no free parameters is the only possible description of our universe's spacetime. They're working on that.

Can we be certain that what we are measuring is what is happening? Is the model extrapolated at such distances?

Can we be certain that what we are measuring is what is happening? Is the model extrapolated at such distances?

There's no distance extrapolation per se. Also, I should say that the validity of the big bang model does not depend solely on stuff at the far ends of the visible universe. The model makes a number of predictions about how the universe ought to look - e.g. it predicts the rough ratio of hydrogen to helium, it predicts the existence of the observed microwave background radiation and the observed fluctuations in that, and so on.

As for certainty, few things are ever 100% certain. All we can say is that, based on current physics, astrophysicists are pretty sure they have the universe's large-scale behaviour fairly well nailed.

This is not to say that there aren't some major puzzles which still need sorting. The glaring ones at the moment are the puzzles of dark matter and dark energy.

There's no distance extrapolation per se. Also, I should say that the validity of the big bang model does not depend solely on stuff at the far ends of the visible universe. The model makes a number of predictions about how the universe ought to look - e.g. it predicts the rough ratio of hydrogen to helium, it predicts the existence of the observed microwave background radiation and the observed fluctuations in that, and so on.

As for certainty, few things are ever 100% certain. All we can say is that, based on current physics, astrophysicists are pretty sure they have the universe's large-scale behaviour fairly well nailed.

This is not to say that there aren't some major puzzles which still need sorting. The glaring ones at the moment are the puzzles of dark matter and dark energy.

Maybe I misunderstood, don't we need to measure the distance of the distant galaxy from us? I was just wondering how exact that science is,

Maybe I misunderstood, don't we need to measure the distance of the distant galaxy from us? I was just wondering how exact that science is

It's reasonably exact.

Distances are measured in astronomy by building up a "ladder" of distance scales, starting from things that are close to us and gradually working outwards to similar objects we can see with telescopes.

For example, we can fairly directly determine the distance from Earth to the Sun. Then, by looking at the orbits of the other planets we can determine how big the solar system is. We can use certain methods (e.g. parallax) to determine the distances to the nearest stars. We can classify stars into certain types according to their spectral colours, and we know what the absolute luminosity of each kind of star should be. Using that, and the apparent luminosities of distant stars of the same type (the type can be determined in various ways), we can determine the distances to many of the stars in our galaxy, and even the distances to some stars in other galaxies.

Looking at the motion of nearby galaxies, we discover the Hubble law. Since we can measure the recession speeds of stars and distance galaxies very accurately (from spectral details), we then can determine the distances of even very distant galaxies. This process is complicated by a number of factors (e.g. gas and dust between us and the distant objects), but we know how to correct for that.

So, in summary, we have a fairly good handle on universal distances. Uncertainties are well quantified.

Thanks

James, what is your opinion on what is going to happen to the universe? Is it going to turn into a dark and dead metal junkyard?

Hello James,

If you're going to posit that the expansion has something to do with individual objects (like galaxies) and not space itself, then you need to ask why the observed expansion is so uniform. For example, why is it that the speed v of every distant galaxy is related to its distance from us x by v = Hx, where H is a constant that is the same for all galaxies?
Isn't an explosion a fairly uniform expansion? And that is not the space itself expanding, right? Besides, the Hubble constant measure some form of force that is perceived with a redshift. That doesn't mean the redshift is an evidence for the universe expansion.

Another interesting observation is that seemingly, with all galaxies apparently moving away from us, we are at the centre of the expansion. Does that mean Earth is the centre of the universe after all? (Hint: physicists say no.)
Yes. And because of this I question whether the universe is actually expanding or not. Everything that expands, expands from a central point. Take for instance a ballon. When it expands, it has a centre from which it expands. Without that centre there is no way to perceive an expansion. The universe has no centre. So how come the universe is expanding?

Another issue that, in my opinion, disproves the expansionary theory is that we actually observe a blueshift with a few galaxies. For instance, the local group is actually getting closer together. Andromeda will be colliding with us in a few billion years and the Magellean Clouds will be colliding with us pretty soon. Now, you can argue that that is due to the strong gravitational force of those galaxies' proximity compared to galaxies far away. However, the Virgo cluster is one example of an extra-galactic object that is actually moving closer to us (blueshift). So how would you explain that blueshift?

I mean.. my question is... what if the redshift doesn't mean the universe is expanding? There's one way that could be happening- rotation. Picture this... do you see the tires of a car? Well, if you pick any point on it (let's say X) while it is rotating, you will see that the points that are away from X and on the direction of the rotation (let's say Y points) may appear to be moving away from Y if you compare with points Z, which are "behind" point X, given the direction of the rotation. So in this model, from the perspective of X, most points would appear to be moving away (because they are ahead in the rotation), while a few points would appear to be moving closer (because they are right behind). Given the age of the universe, I would assume the correct interpretation to be a past redshift (galaxies that have a redshift are seen from a past perspective) while blueshifts would be a look into the future.

Actually, it might be the other way around. Maybe local groups get closer together and eventually become quasars...
In which case we have a bright future ahead.. LOL!! :D

Isn't an explosion a fairly uniform expansion? And that is not the space itself expanding, right? Besides, the Hubble constant measure some form of force that is perceived with a redshift. That doesn't mean the redshift is an evidence for the universe expansion.

I am pretty sure theorists suppose that space-time itself is expanding. They came up with that before they noticed the redshift... the redshift discovery was more of a confirmation to the expansion supposition


Yes. And because of this I question whether the universe is actually expanding or not. Everything that expands, expands from a central point. Take for instance a ballon. When it expands, it has a centre from which it expands. Without that centre there is no way to perceive an expansion. The universe has no centre. So how come the universe is expanding?


When something is stretching uniformly, at any point of this something where you try to measure recession, it will appear as this point is central.

I am pretty sure theorists suppose that space-time itself is expanding. They came up with that before they noticed the redshift... the redshift discovery was more of a confirmation to the expansion supposition
Another reason for suspicion.... ;)

When something is stretching uniformly, at any point of this something where you try to measure recession, it will appear as this point is central.
So... if I stand at any point within the balloon... it will appear the central point? But the distance between the farthest points would be difference. That is... it will be closer to the end of one side then to the other.....

So... if I stand at any point within the balloon... it will appear the central point? But the distance between the farthest points would be difference. That is... it will be closer to the end of one side then to the other.....

How about this... your plane of existence is on the surface of a sphere. Imagine it is expanding. No matter where you live on the sphere, you appear to be the center point of it all. It's expanding in 3D, but since you live in 2D, all you can see is what is on your plane of existence.

Another reason for suspicion.... ;)


So... if I stand at any point within the balloon... it will appear the central point? But the distance between the farthest points would be difference. That is... it will be closer to the end of one side then to the other.....

The redshift is not the only observational evidence of the universe's expansion.
I suggest you read the wikipedia article on metric expansion of space... it explains the distance thing among other interesting things

Varda:

James, what is your opinion on what is going to happen to the universe? Is it going to turn into a dark and dead metal junkyard?

It currently looks a bit that way. According to the best guess at the moment (which is a fairly informed guess), the universe will expand forever. All the stars will eventually burn out, leaving behind a junkyard of dark, cold stuff and a few black holes. There'll be no useful energy left anywhere, and nowhere better to go.

Mind you, we have a while before that happens. :)

I am pretty sure theorists suppose that space-time itself is expanding. They came up with that before they noticed the redshift... the redshift discovery was more of a confirmation to the expansion supposition

Yes. Einstein's original model of the universe came before Hubble noticed that the universe is actually expanding.


Truthseeker:

Isn't an explosion a fairly uniform expansion? And that is not the space itself expanding, right? Besides, the Hubble constant measure some form of force that is perceived with a redshift. That doesn't mean the redshift is an evidence for the universe expansion.

Nobody has come up with a more likely explanation.

The current best explanation is that it is space that is expanding, and not things moving in space. Like I said before, if you think it is things moving in space, then how do you account for the amazing coincidence of the uniformity of the expansion and the Hubble law?

Yes. And because of this I question whether the universe is actually expanding or not. Everything that expands, expands from a central point. Take for instance a ballon. When it expands, it has a centre from which it expands. Without that centre there is no way to perceive an expansion. The universe has no centre. So how come the universe is expanding?

When you talk about a balloon, it has a centre that is not part of the surface of the balloon. Similarly, when you talk about our universe, the "centre" of the expansion is not part of out spacetime as it exists "now". If you're restricted to the surface of the balloon, you can't point to the centre of the expansion, and every direction along the surface is expanding at the same rate. Similarly, we are restricted to a particular slice of spacetime, and we can't point to the centre of our universe's expansion.

You made one mistake above: we can perceive the expansion, just as somebody on the surface of an expanding planet Earth would be able to perceive the expansion just by making measurements on the surface.

Another issue that, in my opinion, disproves the expansionary theory is that we actually observe a blueshift with a few galaxies. For instance, the local group is actually getting closer together. Andromeda will be colliding with us in a few billion years and the Magellean Clouds will be colliding with us pretty soon. Now, you can argue that that is due to the strong gravitational force of those galaxies' proximity compared to galaxies far away.

That's exactly what is argued. All of these galaxies are gravitationally bound. That's why it's called the Local Group.

However, the Virgo cluster is one example of an extra-galactic object that is actually moving closer to us (blueshift). So how would you explain that blueshift?

I'm not really aware of this. How far away is the Virgo cluster?

Well I still subscribe stubbornly to the occilating theory. Eventually, after the "universe"(there might be more - outside "known" space we can't see) stops expanding and does what James described everything coagulates into super massive multigalaxy blackholes with occasional re bursts of energy until one OMEGA black hole forms...then erupts into another big bang or ALPHA quasar.

It is possible we are one of many of these "universes" for lack of a better term. Universe originally means "everything" including other...alpha/omega dramas. There is really no evidence yet to support it.

Just to add abit more here.

The expansion is considered to be fact because thousands of independent observations have given the exact same results.

And the reason space is also considered to be expanding is due to the fact that all the most distant objects are moving at speeds that exceed the speed of light. And since matter cannot do that, it has to be space itself that's expanding - not the material objects themselves.

What is it just radiation?

All the analogies are all well and good (if) one thinks of (space) as a
material, some thing that has properties, we know space has electrical
properties but, its proposed ability to stretch and bend AFAIK have never
been demonstrated.
If we confined our observations to nothing but our own galaxy ,there would
be no way to observe space expanding, as it is only non gravitationally
bound bodies that are seemingly getting further apart.
The idea that bodies can exceed the speed of light (if) they are (fixed) to
space seems to be slight of hand trick ,as is the idea that space can be (formed) by gravity.
Until i can find a definition of what space (is) any explanation scientists
give will remain hollow.

All the analogies are all well and good (if) one thinks of (space) as a
material, some thing that has properties, we know space has electrical
properties but, its proposed ability to stretch and bend AFAIK have never
been demonstrated.
If we confined our observations to nothing but our own galaxy ,there would
be no way to observe space expanding, as it is only non gravitationally
bound bodies that are seemingly getting further apart.
The idea that bodies can exceed the speed of light (if) they are (fixed) to
space seems to be slight of hand trick ,as is the idea that space can be (formed) by gravity.
Until i can find a definition of what space (is) any explanation scientists
give will remain hollow.

Quite the contrary, in fact. The requirement is that space be a non-material.

You are certainly free to believe whatever you wish - but everything you've just said indicates you have little real knowledge of the subject. Perhaps a little studying might be in order before you oppose what thousands of professionals accept?

Quite the contrary, in fact. The requirement is that space be a non-material.

You are certainly free to believe whatever you wish - but everything you've just said indicates you have little real knowledge of the subject. Perhaps a little studying might be in order before you oppose what thousands of professionals accept?


Which makes no sense whatsoever, scientists have (given) space these
proposed properties, not me, so what the heck are you on about?
Maybe you have such an in depth understanding of what space is that you
can explain all the above valid observations, without resulting to rhetoric.

Which makes no sense whatsoever, scientists have (given) space these
proposed properties, not me, so what the heck are you on about?

The fact that space itself must be non-material for the material objects in it to move at speeds higher than c. And as I said, they have made many, many observations that bear out those facts.

So now the question becomes: what's YOUR problem?????

The fact that space itself must be non-material for the material objects in it to move at speeds higher than c. And as I said, they have made many, many observations that bear out those facts.

So now the question becomes: what's YOUR problem?????

What you say is just total and utter nothing, space is non material? and yet
it can expand, can be warped by gravity, has electrical properties, get real,
as i have said (i) did not imagine these scientificaly given properties, scientists did.

What you say is just total and utter nothing, space is non material? and yet it can expand, can be warped by gravity...

You need to realise that the expansion of space is not like stretching a rubber sheet. All it means is that the physical distances between any two objects tend to become larger over time.

And warping isn't like the rubber sheet, either. That's an analogy that physicists use to try to explain it to the average non-physicist. The problem comes when non-physicists start to imagine that the analogy is the theory, like you seem to be doing.

... has electrical properties...

Space has no electrical properties.

What you say is just total and utter nothing, space is non material? and yet
it can expand, can be warped by gravity, has electrical properties, get real,
as i have said (i) did not imagine these scientificaly given properties, scientists did.

You simply don't know enough to realize what YOU are saying is totally absurd. Certainly space can expand - it's just the distance between points. And where did you you get the crazy notion that ANY scientist ever said space has electrical properties????????????????? Time for you get real - go back to school. And if you're still there (which I suspect to be the case) stay until you learn a lot more.

What does the constant 'epsilon0' refer to?

How about this... your plane of existence is on the surface of a sphere. Imagine it is expanding. No matter where you live on the sphere, you appear to be the center point of it all. It's expanding in 3D, but since you live in 2D, all you can see is what is on your plane of existence.
Humm... yes... I heard that explanation several times. Unfortunately, the universe is believded to be flat. For a matter of fact, the same characteristics that support the Big Bang support the flatness of the universe. However, you see the problem with having a flat universe on the surface of a balloon, don't ya? ;)

The redshift is not the only observational evidence of the universe's expansion.
I suggest you read the wikipedia article on metric expansion of space... it explains the distance thing among other interesting things
The redshift is currently the major evidence in favor of accelerating expansion. Without it, inflation is nothing but a whole bunch of weak hypothesis tied together!

You need to realise that the expansion of space is not like stretching a rubber sheet. All it means is that the physical distances between any two objects tend to become larger over time.

And warping isn't like the rubber sheet, either. That's an analogy that physicists use to try to explain it to the average non-physicist. The problem comes when non-physicists start to imagine that the analogy is the theory, like you seem to be doing.



Space has no electrical properties.

Heck, give me an explanation of what (you think )this (non entity) is ,that can some how cause bodies to get further apart, please no more rhetoric, a proof of what space is, i suspect you are relying on some suspect logic and
are able to twist it to your ideas.

Humm... yes... I heard that explanation several times. Unfortunately, the universe is believded to be flat. For a matter of fact, the same characteristics that support the Big Bang support the flatness of the universe. However, you see the problem with having a flat universe on the surface of a balloon, don't ya? ;)

Sorry, but I have to ask. Where did you come up with the idea that the universe is flat??? There's nothing I'm aware of that even remotely indicates that. And besides, the big bang also supports a spherically shaped universe as well.

Yes. Einstein's original model of the universe came before Hubble noticed that the universe is actually expanding.
Did he actually interepret the data as expansion or did he just get the data?

Nobody has come up with a more likely explanation.
A flat planet also seemed the most likely explanation just 500 years ago...

The current best explanation is that it is space that is expanding, and not things moving in space.
I'm not debating what is expanding, I'm debating whether there is anything expanding at all.

Like I said before, if you think it is things moving in space, then how do you account for the amazing coincidence of the uniformity of the expansion and the Hubble law?
Again, is it really expansion? The idea of expansion is a simple interpretation of the data. Too often, we look at the data we get, interpret it in one way and forget there might be other interpretations to it. I just plain have a gut feeling the universe is not expanding. I have a gut instinct it is rotating, like the galaxy. The galaxy also exihibits a very uniform behaviour (aside from the region close to the centre, of course. The speed of the arms is fairly uniform).

We have to remember that altough the laws of the universe apply to the whole universe, objects will behave differently according to the scale due to the range and strenght that each force has. First of all, you have the rotation of our planet. The speed doesn't vary much, Then we have the rotation of the sun. The speed of the sun's rotation varies. The speed at the equator is different then the speed at the poles. Then you have the rotation of the solar system. Once again, we have the same laws but the objects behave differently due to the scale. Then, the galaxy is also rotating, and the differences of speed are currently explained only by the terms "dark energy" and "dark matter". Then we have clusters and super clusters and quasars! Massive! Everything in the universe is rotating. Wouldn't it be strange if the universe itself wasn't? Maybe redshifts and blueshifts give us a clue about the rotation of the universe...


When you talk about a balloon, it has a centre that is not part of the surface of the balloon. Similarly, when you talk about our universe, the "centre" of the expansion is not part of out spacetime as it exists "now".
When you look at a quasar, are you looking at it right now or in the past? Also, what is the shape of the universe? Is it a sphere?

If you're restricted to the surface of the balloon, you can't point to the centre of the expansion, and every direction along the surface is expanding at the same rate.
The earth is like a ballon. All that I need to do to point to its center is to point right below me. Why can't I do the same with this version of the universe?

You made one mistake above: we can perceive the expansion, just as somebody on the surface of an expanding planet Earth would be able to perceive the expansion just by making measurements on the surface.
Really? Or would it appear that everything is static because for a matter of fact everything is expanding? Could you really observe it given the scale?

I'm not really aware of this. How far away is the Virgo cluster?
Here's some info on Virgo: http://en.wikipedia.org/wiki/Virgo_cluster

Some details: http://seds.lpl.arizona.edu/messier/more/virgo_gal.html

Sorry, but I have to ask. Where did you come up with the idea that the universe is flat??? There's nothing I'm aware of that even remotely indicates that. And besides, the big bang also supports a spherically shaped universe as well.
The universe is 'flat' in the sense that parallel lines do not converge nor diverge as they do on curved surfaces.

The expansion is considered to be fact because thousands of independent observations have given the exact same results.
The expansion is an interpretation of the data.

And the reason space is also considered to be expanding is due to the fact that all the most distant objects are moving at speeds that exceed the speed of light. And since matter cannot do that, it has to be space itself that's expanding - not the material objects themselves.
Let's not forget that distant objects constitutes mostly of massive galaxies called "quasars". Our data only predicts some for of high speed given by the redshifts. Expansion is an interpretation.

What does the constant 'epsilon0' refer to?

The constant epsilon is a feature which describes certain aspects of electric interactions. Its value depends on the environment in which electric fields exist. It is called the "permittivity". Unfortunately, when the environment is a vacuum, the concept is generalised, and the constant espilon zero is given the somewhat unfortunate but understandable name of "the permittivity of the vacuum".

Heck, give me an explanation of what (you think )this (non entity) is ,that can some how cause bodies to get further apart, please no more rhetoric, a proof of what space is, i suspect you are relying on some suspect logic and
are able to twist it to your ideas.

Suppose I attach object A to one end of a metre ruler, and object B to the other end. Then, suddenly and mysteriously, I somehow double the distances between each mark on the ruler, and also the distance between object A and B. Then, I get another, unaltered ruler, and measure the new separation of A and B. What do I find? A and B are now two metres apart, even though they have remained attached to the ends of my original ruler.

Similarly, if objects A and B are sitting at particular coordinates in space, and the physical distances between those coordinates change due to the expansion of space, then when I measure the distance with an unstretched ruler I find that A and B are further apart, even though the coordinate locations of A and B are unchanged.

If you want a technical explanation, the best place to start is any introductory text on general relativity. Would you like me to recommend one?

You are certainly free to believe whatever you wish - but everything you've just said indicates you have little real knowledge of the subject. Perhaps a little studying might be in order before you oppose what thousands of professionals accept?
Argument of authority.
Argument of population.


Busted.... ;)

The fact that space itself must be non-material for the material objects in it to move at speeds higher than c. And as I said, they have made many, many observations that bear out those facts.
I didn't know science believed in non-material things....

Sorry, but I have to ask. Where did you come up with the idea that the universe is flat??? There's nothing I'm aware of that even remotely indicates that. And besides, the big bang also supports a spherically shaped universe as well.
Old news. May 9th, 2000...

Read it here: http://www.abc.net.au/science/news/stories/s124978.htm

"New evidence supports flat Universe
Results from a collaborative experiment confirm that the universe is flat and 95% of it is unknown matter. "


I'm sorry you are so late... LOL! :p ;)

The shape of the universe is very significant to this discussion, btw....

Different shapes will give you different rates of acceleration, desacelaration and stactic. Open and closed universes would also be affected by those shapes and the whole hypothesis is also affect by those two factors.

Fuck... we have barely scracthed the surface of this discussion... :shrug:

Truthseeker:

Did he actually interepret the data as expansion or did he just get the data?

He interpreted it as expansion.

A flat planet also seemed the most likely explanation just 500 years ago...

Maybe we'll have a better big bang theory in another 500 years. So what?

I'm not debating what is expanding, I'm debating whether there is anything expanding at all.

Again, is it really expansion? The idea of expansion is a simple interpretation of the data. Too often, we look at the data we get, interpret it in one way and forget there might be other interpretations to it. I just plain have a gut feeling the universe is not expanding. I have a gut instinct it is rotating, like the galaxy.

The observational evidence rules out rotation. Every direction we look, we see objects moving away from us, not rotating around us. And none are coming towards us (with a few local exceptions).

We have to remember that altough the laws of the universe apply to the whole universe, objects will behave differently according to the scale due to the range and strenght that each force has. First of all, you have the rotation of our planet. The speed doesn't vary much, Then we have the rotation of the sun. The speed of the sun's rotation varies. The speed at the equator is different then the speed at the poles. Then you have the rotation of the solar system. Once again, we have the same laws but the objects behave differently due to the scale. Then, the galaxy is also rotating, and the differences of speed are currently explained only by the terms "dark energy" and "dark matter". Then we have clusters and super clusters and quasars! Massive! Everything in the universe is rotating. Wouldn't it be strange if the universe itself wasn't? Maybe redshifts and blueshifts give us a clue about the rotation of the universe...

Well, all I can say is: do the math and publish your ideas. Submit them to a peer-reviewed journal of physics and see whether they can withstand proper scientific scrutiny.

When you look at a quasar, are you looking at it right now or in the past? [quote]

You're looking at it now. You're seeing it as it was in the past.

[quote]Also, what is the shape of the universe? Is it a sphere?

Nobody knows. Also, it depends what you mean by "shape of the universe". Shape in three dimensional space or four-dimensional spacetime?

Also, locally the universe is quite "lumpy" and irregular, due to the various masses that curve spacetime. It is only on large scales that we can discern an overall geometry.

The earth is like a ballon. All that I need to do to point to its center is to point right below me. Why can't I do the same with this version of the universe?

Because you can't point in the time direction or the 4th spatial direction. You're confined to pointing in the 3 space directions. You have to realise that in the balloon analogy, only the surface of the balloon contains parts of the universe that can be pointed to. The centre can't be pointed to by a surface-dweller. There is no "up" and "down" for a 2-d person living on the surface.

Isnt the universe expansion also accelerating? Whats that about?

You guys gotta remember that every time we have an unexplainable varialbe in the equation, those unexplainable variables points out some sort of flaw in our hypothesis and, thus, our interpretations of our data. Because at the end of the day, that's all taht we are doing. We are not going out there and observing whether the universe is flat or not. We are getting some form of data which allows us to make an indirect observation which, subsequently gives us hints to the actual circumstances of the universe, which are used to give meaning to the data- aka interpretation.

The fact that we have two massive unknown variables (dark matter and dark energy) is a major red flag in this puzzle. We can't always just try to fit the data with our interpretations. At some point, the data that we get will make our interpretations so absurd that we will have to give up onour interpretations and start from the scracth, with a fresh perspective on the issue. In which case, we will have aolot more data then the last time we interpreted the original data, so we will be able to be more accurate in our interpretations... :)

James R,
Similarly, if objects A and B are sitting at particular coordinates in space, and the physical distances between those coordinates change due to the expansion of space, then when I measure the distance with an unstretched ruler I find that A and B are further apart, even though the coordinate locations of A and B are unchanged.
Why can't you treat length contraction in the same manner? Of course, in both cases your 'ruler' would be based on the speed of light.

The constant epsilon is a feature which describes certain aspects of electric interactions. Its value depends on the environment in which electric fields exist. It is called the "permittivity". Unfortunately, when the environment is a vacuum, the concept is generalised, and the constant espilon zero is given the somewhat unfortunate but understandable name of "the permittivity of the vacuum".



Suppose I attach object A to one end of a metre ruler, and object B to the other end. Then, suddenly and mysteriously, I somehow double the distances between each mark on the ruler, and also the distance between object A and B. Then, I get another, unaltered ruler, and measure the new separation of A and B. What do I find? A and B are now two metres apart, even though they have remained attached to the ends of my original ruler.

Similarly, if objects A and B are sitting at particular coordinates in space, and the physical distances between those coordinates change due to the expansion of space, then when I measure the distance with an unstretched ruler I find that A and B are further apart, even though the coordinate locations of A and B are unchanged.

If you want a technical explanation, the best place to start is any introductory text on general relativity. Would you like me to recommend one?

No, i am sorry but ,all your rhetoric leads to some sort of insanity, i do not want to believe in some thing that is not tangible, if you want to believe
in some sort of ghostly reality you are welcome, i challenge you to define what his non entity of space is , a space that can expand , be distorted by gravity and yet is not tangible?

Argument of authority.
Argument of population.


Busted.... ;)

Not in the least. The "argument of authority", as you so glibly put it, is based on the solid principle that the professionals who have been studying the situation for far longer than most people here have even been alive certainly DOES add a huge degree of believability to those positions.

Or would you actually feel more comfortable accepting what's said by some little 15-year-old punk???????????? Or you own untrained thoughts??? Either of those is what I would strongly call absurd! The very day you can out do the professionals is the day you BECOME one of them! So what would that make you then - unbelievable? :bugeye:

He interpreted it as expansion.
Quote?

Maybe we'll have a better big bang theory in another 500 years. So what?
Or simply another theory? What's wrong with Brane theory?
(Well... they are all hypothesis, btw...)

The observational evidence rules out rotation. Every direction we look, we see objects moving away from us, not rotating around us. And none are coming towards us (with a few local exceptions).
As I said, the sun and the galaxy rotates at different speeds depending on where you look at. Can't the same happen with the universe?

You're looking at it now. You're seeing it as it was in the past.
Yes. And when you look at the past, wouldn't it be reasonable to argue that at some point you will see the Big Bang- that is, the "centre" of the universe? Haven't we been trying to do that for a while now?

Nobody knows. Also, it depends what you mean by "shape of the universe". Shape in three dimensional space or four-dimensional spacetime?
Do we even know there are only 4 dimensions?

Also, locally the universe is quite "lumpy" and irregular, due to the various masses that curve spacetime. It is only on large scales that we can discern an overall geometry.
Well, barely. Distant objects are so massive I wonder how they distort space-time. Gravity lenses make the universe more like a house of mirrors then anything that barely resembles something discernable... LOL!!! :D

Because you can't point in the time direction or the 4th spatial direction. You're confined to pointing in the 3 space directions. You have to realise that in the balloon analogy, only the surface of the balloon contains parts of the universe that can be pointed to. The centre can't be pointed to by a surface-dweller. There is no "up" and "down" for a 2-d person living on the surface.
Again, then explain this: http://www.as.arizona.edu:8080/Astro/1042673451/index_html

Three quasars at the "Edge" of the universe? Which "Edge"?
Quoted from article:

"These discoveries are giving us the first glimpse of the universe when it was only 5 percent of its present age."

Sounds like we can see towards the centre....

Not in the least. The "argument of authority", as you so glibly put it, is based on the solid principle that the professionals who have been studying the situation for far longer than most people here have even been alive certainly DOES add a huge degree of believability to those positions.

Or would you actually feel more comfortable accepting what's said by some little 15-year-old punk???????????? Or you own untrained thoughts??? Either of those is what I would strongly call absurd! The very day you can out do the professionals is the day you BECOME one of them! So what would that make you then - unbelievable? :bugeye:
HAHAHA!!!! :D

No. The argument from authority does not disprove their point. It siply points out to the fact that just because they are experts, doesn't mean their words are set on stone. An expert of the subject 500 years ago wouldd think those guys today are completely nuts! LOL!!! :D

Not in the least. The "argument of authority", as you so glibly put it, is based on the solid principle that the professionals who have been studying the situation for far longer than most people here have even been alive certainly DOES add a huge degree of believability to those positions.

Or would you actually feel more comfortable accepting what's said by some little 15-year-old punk???????????? Or you own untrained thoughts??? Either of those is what I would strongly call absurd! The very day you can out do the professionals is the day you BECOME one of them! So what would that make you then - unbelievable? :bugeye:

Please, your ideas of what is right or wrong in science is some what distorted by obscured, non proven, even conjectured views of what is accepted by main stream view.

HAHAHA!!!! :D

No. The argument from authority does not disprove their point. It siply points out to the fact that just because they are experts, doesn't mean their words are set on stone. An expert of the subject 500 years ago wouldd think those guys today are completely nuts! LOL!!! :D

No argument against that! In fact, there's little doubt in anyone's mind that the current theories will change in the future. Real science is an adventure that never ends. But at the same time, there's very, very little chance that better answers can possibly spring from untrained minds. ;)

Please, your ideas of what is right or wrong in science is some what distorted by obscured, non proven, even conjectured views of what is accepted by main stream view.

Bull!!! You haven't even the vaguest idea of what you're talking about. Electrical properties of space, indeed! Yuck!!! As I said earlier, don't quit school anytime soon - you've got LOTS to learn yet.

Guys if you want to revert to some basic science , the only reality we have is geometry, all the rest is conjecture, proposed by some big balled scientists,
who think the general public can be hoodwinked into thinking they know more
than we do, when it comes to cosmology talk, you may as well listen to ufology talk.

Not in the least. The "argument of authority", as you so glibly put it, is based on the solid principle that the professionals who have been studying the situation for far longer than most people here have even been alive certainly DOES add a huge degree of believability to those positions.

Or would you actually feel more comfortable accepting what's said by some little 15-year-old punk???????????? Or you own untrained thoughts??? Either of those is what I would strongly call absurd! The very day you can out do the professionals is the day you BECOME one of them! So what would that make you then - unbelievable? :bugeye:

Bull!!! You haven't even the vaguest idea of what you're talking about. Electrical properties of space, indeed! Yuck!!! As I said earlier, don't quit school anytime soon - you've got LOTS to learn yet.

more Rhetoric? why do you even bother to post?

Truthseeker:

You guys gotta remember that every time we have an unexplainable varialbe in the equation, those unexplainable variables points out some sort of flaw in our hypothesis and, thus, our interpretations of our data.

Not necessarily. Parameters merely allow for our lack of knowledge at the present time. As new data comes in, we tighten up on the possible values of the parameters. In other words, parameters help to quantify what we do not yet know for sure.

Because at the end of the day, that's all taht we are doing. We are not going out there and observing whether the universe is flat or not. We are getting some form of data which allows us to make an indirect observation which, subsequently gives us hints to the actual circumstances of the universe, which are used to give meaning to the data- aka interpretation.

That's what science is all about.

The fact that we have two massive unknown variables (dark matter and dark energy) is a major red flag in this puzzle.

Technically, dark matter and energy are not variables. They are attempts at explanations for observations that put certain values on variables (parameters). These explanations may ultimately turn out to be wrong, but that won't change the known data. We'll just need another explanation.

We can't always just try to fit the data with our interpretations. At some point, the data that we get will make our interpretations so absurd that we will have to give up onour interpretations and start from the scracth, with a fresh perspective on the issue. In which case, we will have aolot more data then the last time we interpreted the original data, so we will be able to be more accurate in our interpretations... :)

Again, that's what science is all about.

And when you look at the past, wouldn't it be reasonable to argue that at some point you will see the Big Bang- that is, the "centre" of the universe? Haven't we been trying to do that for a while now?

As I said, the universe has no centre in space. When we look out far enough we can see back to a time not long after the big bang, but the bang happened everywhere, not at some point in space.

The microwave background radiation is from the big bang. It is what we see when we look to the edge of the observable universe.

Do we even know there are only 4 dimensions?

We don't, but we know for sure there are at least 4.

Again, then explain this: http://www.as.arizona.edu:8080/Astro/1042673451/index_html

Three quasars at the "Edge" of the universe? Which "Edge"?

Sloppy wording in a press release. They mean the "edge" of the visible universe - that is, the furthest back in time we can look.

Quoted from article:

"These discoveries are giving us the first glimpse of the universe when it was only 5 percent of its present age."

Sounds like we can see towards the centre....

There is no centre.


Nickelodeon:

Isnt the universe expansion also accelerating? Whats that about?

It means that the average distances between galaxies are getting larger at an ever-increasing rate.


2inquisitive:

Why can't you treat length contraction in the same manner? Of course, in both cases your 'ruler' would be based on the speed of light.

Length contraction is a result of relative motion. When you stop moving, length contraction goes away. The expansion of the universe doesn't go away. All observers agree the universe is expanding, regardless of their motion.


fishtail:

No, i am sorry but ,all your rhetoric leads to some sort of insanity, i do not want to believe in some thing that is not tangible, if you want to believe in some sort of ghostly reality you are welcome...

Thankyou.

... i challenge you to define what his non entity of space is , a space that can expand , be distorted by gravity and yet is not tangible?

I just use the standard general relativistic definitions of spacetime coordinates etc.

Do you know of a better way of defining space?

Guys if you want to revert to some basic science , the only reality we have is geometry, all the rest is conjecture, proposed by some big balled scientists, who think the general public can be hoodwinked into thinking they know more than we do, when it comes to cosmology talk, you may as well listen to ufology talk.

Well, you're the expert. You're qualified to evaluate the status of cosmology, I'm sure.

James R,
Length contraction is a result of relative motion.
Uh, OK. Now which objects can I look at to confirm this prediction? Not the ones moving at great relative speeds due to the expansion of the universe, I presume.
All observers agree the universe is expanding, regardless of their motion.
So regardless of the observer's motion relative to a distant object, the distance won't appear to contract and the object will always appear to be moving away from the observer?? I thought you just said length contraction is a result of relative motion?

Sorry James, but I just couldn't help it! :D

The impression I get from reading this thread is that nobody except James R has a grip at this subject. I think some reading on basic concepts of cosmology, such as the relativity theory and metric expansion of space would substantially improve the quality of this discussion.

The impression I get from reading this thread is that nobody except James R has a grip at this subject. I think some reading on basic concepts of cosmology, such as the relativity theory and metric expansion of space would substantially improve the quality of this discussion.

So maybe you can tell us what the 95% of the missing mass of the universe is? the arxivs are full of papers telling us that scientists do not know what it is, and that every proposed test is all ways just beyond reach.
So Varda sit down and tell us what is known about cosmology, the parts
that are testable today.

Please, don't be offended fishtail. It is just very difficult to discuss things that scientists are in doubt about, when even things that scientists are mostly certain about are being so blatantly missunderstood. I don't thing we should skip to more complex subjects when the basics are still going over people's heads.

The impression I get from reading this thread is that nobody except James R has a grip at this subject. I think some reading on basic concepts of cosmology, such as the relativity theory and metric expansion of space would substantially improve the quality of this discussion.

Ouch...runs away with tail between his legs...

Really this is a subject somewhat open to a lot of interpretation. We have such a small window of "time" to view the "universe".

Technically, dark matter and energy are not variables. They are attempts at explanations for observations that put certain values on variables (parameters). These explanations may ultimately turn out to be wrong, but that won't change the known data. We'll just need another explanation.
Well, yes, they are interpretations of our data. But basically, we are measuring two things which we identify as "dark matter" and "dark energy".

As I said, the universe has no centre in space. When we look out far enough we can see back to a time not long after the big bang, but the bang happened everywhere, not at some point in space.
Wouldn't the brane theory make more sense, then?

The impression I get from reading this thread is that nobody except James R has a grip at this subject. I think some reading on basic concepts of cosmology, such as the relativity theory and metric expansion of space would substantially improve the quality of this discussion.
James R knows his shit, but he doesn't try to test the theory and play with it. I could tell you everything I know about cosmology and it would sound not much different then what James R has to say. But I much rather challenge our interpretations of the data, as opposed to simply restating the commonly accepted interpretations.

I don't see much of a point in simply agreeing with the interpretations we have as supposed to trying to find interpretations that fit all the data we have collected- that is, including dark matter and dark energy.

So... tell me, if you are so knowledgeable of the subject... tell me what you think about our galaxy. Do you think there is really dark matter in our galaxy or the anomalies we observe in the galaxy's rotation patterns can actually be explained without dark matter? What about quasars? Do you think they would behave exactly the same way our galaxy does, but with a much bigger scale? Or there is something special about quasars?

James R,

What do you think is the shape of the universe? It sounds like you believe the universe is like a sphere...

Please, don't be offended fishtail. It is just very difficult to discuss things that scientists are in doubt about, when even things that scientists are mostly certain about are being so blatantly missunderstood. I don't thing we should skip to more complex subjects when the basics are still going over people's heads.


I am not in least bit offended :) all i want to know is what is the (hard core)
to cosmology and why people think they are on the right track.
It is unfair of scientists to propose way out theories and then talk down to us
because we are to stupid to accept them chapter and verse.
Maybe a theory can be right with 95% of it missing but, is it questionable?
to right it is.

so the universe is either infinate in size wich allows matter to expand into itself, or it has walls and limits,




peace.

so the universe is either infinate in size wich allows matter to expand into itself, or it has walls and limits,




peace.


There are no walls, the universe can be infinite but bounded, all this means is
that from where ever you start a journey, traveling in a straight line you will
all ways eventually end up back at your starting point,
That is not including the expantion of space, with this you will never reach
your journey's end.

There are no walls, the universe can be infinite but bounded, all this means is
that from where ever you start a journey, traveling in a straight line you will
all ways eventually end up back at your starting point,
That is not including the expantion of space, with this you will never reach
your journey's end.


you cant end up where you started at unless you just walked in a circle or around a sphear like the earth, there is nothing indicating that the universe is a sphear. how do you explain ending up where you started at?


peace.

Have a look at this wiki article.



http://en.wikipedia.org/wiki/Shape_of_the_Universe

A compact space is a general topological definition that encompasses the more applicable notion of a bounded metric space. In cosmological models, it requires either one or both of: the space has positive curvature (like a sphere), and/or it is "multiply connected", or more strictly non-simply connected.

If the 3-manifold of a spatial section of the universe is compact then, as on a sphere, straight lines pointing in certain directions, when extended far enough in the same direction will reach the starting point and the space will have a definable "volume" or "scale". If the geometry of the universe is not compact, then it is infinite in extent with infinite paths of constant direction that, generally do not return and the space has no definable volume, such as the Euclidean plane.

If the spatial geometry is spherical, the topology is compact. Otherwise, for a flat or a hyperbolic spatial geometry, the topology can be either compact or infinite.

that doesent mean that if you keep going straight that you will end up where you started, for expansion to take place from what we can gather from lab experiments and actual tests we conduct, you need existing space for mass to expand into,

an infinite universe would explain this, your theory relys on dark energy if i am not mistaken?


peace.

i will read the wikipedia page now.

peace.

I think there's some confusion here about how science actually works in practice, and what scientists do.

So maybe you can tell us what the 95% of the missing mass of the universe is? the arxivs are full of papers telling us that scientists do not know what it is, and that every proposed test is all ways just beyond reach.

Fair comment. Scientists do not yet know what the missing mass is. But that's ok. There are always things we don't know about the universe. On the edges of knowledge, people are always searching for explanations, and what is happening in cosmology is the same as is happening in stem cell research, or nuclear fusion research, or any other area of cutting-edge science.

I don't know how you think new knowledge is generated. You must realise that at some stage every "fact" goes from being unknown to known and accepted. And that means that science will never have all the answers. Science is a gradual pushing back of the limits of knowledge.


Wouldn't the brane theory make more sense, then?

As far as I am aware, brane theory is completely compatible with the big bang. I personally am not a string theorist, so I'm not qualified to comment on the ins and outs of brane theory. To do so would be worth little more than an uneducated guess.

James R knows his shit, but he doesn't try to test the theory and play with it.

That's correct. I am not a cosmologist. I am not an expert in general relativity, even. I've only taken one graduate-level course in GR.

I know how much I don't know.

I prefer to leave the development of cutting-edge cosmological theories to people who have chosen to dedicate their lives to the field of cosmology - the experts in that field. Who am I, who knows almost nothing in comparison, to say that my guesses about cosmology are better than their informed analyses?

Would you tell an electrician how to fix the wiring in your house? If you're qualified to do that, perhaps you'd just fix it yourself. But if you're not an expert, you leave that stuff to the experts. So why, when it comes to experts in academic fields, do people presume that their opinions are just as good as those of the people who have studied and whose job it is to work on those things?

I could tell you everything I know about cosmology and it would sound not much different then what James R has to say. But I much rather challenge our interpretations of the data, as opposed to simply restating the commonly accepted interpretations.

What I would ask is: Are you qualified to challenge the interpretations? Can you understand brane theory sufficiently to comment on it? Can you do the math? And if not, what on earth makes you think you'll come up with anything remotely useful in that field, that hasn't already been carefully examined by the real experts?

What do you think is the shape of the universe? It sounds like you believe the universe is like a sphere...

I don't know what shape the universe is. The visible universe is certainly a sphere - light has only been able to travel for 14 billion years or so, so we can't possibly see anything further away than the edge of a sphere 14 billion light years in radius. But what is beyond that? There's no way of knowing.

As for the spacetime geometry of the universe on the largest scales, current data says it is approximately flat (in 4D). The accelerating expansion is thought to be due not to spacetime curvature, but due to the presence of "dark energy", which appears in Einstein's equations as the "cosmological constant".

As for the spacetime geometry of the universe on the largest scales, current data says it is approximately flat (in 4D). The accelerating expansion is thought to be due not to spacetime curvature, but due to the presence of "dark energy", which appears in Einstein's equations as the "cosmological constant".

A pushing or a pulling effect? The acceleration I mean. Do they know?

A pushing or a pulling effect? The acceleration I mean. Do they know?

Well, we're talking about dark energy that exists between and within galaxies, so I guess it's a kind of push outwards - an anti-gravity effect.

I see, so some kind of force that still "feels" contained and is still pushing against matter?

I prefer to leave the development of cutting-edge cosmological theories to people who have chosen to dedicate their lives to the field of cosmology - the experts in that field. Who am I, who knows almost nothing in comparison, to say that my guesses about cosmology are better than their informed analyses?
Who needs to compete with them? We are here to have a discussion on an interesting subject- that is all. I don't care if my ideas are published or not and that I get famous like Einstein. I'm just having fun here.

Would you tell an electrician how to fix the wiring in your house? If you're qualified to do that, perhaps you'd just fix it yourself. But if you're not an expert, you leave that stuff to the experts. So why, when it comes to experts in academic fields, do people presume that their opinions are just as good as those of the people who have studied and whose job it is to work on those things?
Again, I don't pressume my opinions are better. I just use logic to come upi with educated guesses.

Of course, I did study quite a bit on those subjects.... But they study it in depth for years. So... ya know...

What I would ask is: Are you qualified to challenge the interpretations?
I'm not challenging them. I'm trying to understand them better by questioning them.

Can you understand brane theory sufficiently to comment on it?
Yes. I can comment on it. It's a relatively "simple" theory.

Can you do the math?
The math is done. I just use the data I get to make logical guesses (interpretations).

And if not, what on earth makes you think you'll come up with anything remotely useful in that field, that hasn't already been carefully examined by the real experts?
Why would I care. I'm thinking about this stuff because I have fun thinking about this stuff. Huuummm.... coffee and advanced physics early in the morning... So good... LOL! :D

Do you think i should be a physicist? Yes, I have considered that. But there were two problems with that. First of all, I find basic physics pretty boring, and I would have to go through that first (again). Second, I'm not rich. Physicists get paid shit. Why would I do that when I have a wife and two kids?

I don't know what shape the universe is. The visible universe is certainly a sphere - light has only been able to travel for 14 billion years or so, so we can't possibly see anything further away than the edge of a sphere 14 billion light years in radius. But what is beyond that? There's no way of knowing.
You say you don't know and yet you write all that. You are so humble... :)

As for the spacetime geometry of the universe on the largest scales, current data says it is approximately flat (in 4D). The accelerating expansion is thought to be due not to spacetime curvature, but due to the presence of "dark energy", which appears in Einstein's equations as the "cosmological constant".
Do you think there is a 5th dimension characterized by the dark energy that makes the universe expand on a spheric way?

I mean... Do you think that the 4 dimensions are on the surface of that sphere and that the 5th dimension is the radius of that sphere (and that dark energy is the force that is making the 5th dimension "expand")?

Cause that's what I always imagined... :)

A pushing or a pulling effect? The acceleration I mean. Do they know?
What if dark energy is actually outside the universe and it is pulling it? If it's "Dark", maybe we cannot see it because it is outside!!!! ;)

What if dark energy is actually outside the universe and it is pulling it? If it's "Dark", maybe we cannot see it because it is outside!!!! ;)

AFAIK, no one has a handle on dark energy, at a guess it will be proved to be a relic of cosmological maths, can anyone understand how difficult it is to
homogenise a theory for the mechanics of our universe? It will not happen this year, next year, next century, it may be never will, the best we can do is keep guessing and hope to strike lucky.

Truthseeker:

Do you think there is a 5th dimension characterized by the dark energy that makes the universe expand on a spheric way?

I'm not convinced the universe expands in a "spheric way". Remember that there's no centre we can point to in our universe.

I mean... Do you think that the 4 dimensions are on the surface of that sphere and that the 5th dimension is the radius of that sphere (and that dark energy is the force that is making the 5th dimension "expand")?

I don't know whether the 4-dimensions of space and time are on the surface of some larger hypersphere, or some other higher-dimensional surface. But bear in mind that we see our visible spatial dimensions expanding - not just some invisible 5th dimension.

I love mind-bending puzzles... LOL!!

I'm not convinced the universe expands in a "spheric way". Remember that there's no centre we can point to in our universe.
Well, yes, there is no centre for the visible universe- the one at the surface. But what about the universe that once was the universe? I mean... take the universe as spheric. In this scenario, wouldn't the radius of the sphere expand throughout time? Then, wouldn't the past radi be the universes that once were in the past? Then, if you go all the way to the Big Bang, the radius of the sphere would be 0, and in the "centre" of the universe. So in this scenario, the radius of the sphere would equal "time", in the fith dimension. :bugeye:

Man... this would be easier if I could show you a picture... LOL! :D

So... What if the past universe is still there? What if every time the universe expands, a copy of the universe is made? Then, wouldn't that explain the "dark" matter? In this scenario, the "dark" matter would be the accumulated matter of the whole universe history in the background of the universe (ie 5th dimension, the radius of the "universe"). The visible universe would be the 4 dimensional "flat" surface of the sphere. The rest of the universe (the invisible part) would be on the background, within the layers of this sphere. As time goes by and matter continues to accumulate in the invisible universe, then the amount of dark energy created increases, which causes the expansion to further accelerate.

I don't know whether the 4-dimensions of space and time are on the surface of some larger hypersphere, or some other higher-dimensional surface. But bear in mind that we see our visible spatial dimensions expanding - not just some invisible 5th dimension.
Well.. what I have imagined before was that the invisible 5th dimension would superimpose the visible ones. So if you take our galaxy, for instance, the invisible matter would still be right "behind" the galaxy. And as I said before, this invisible matter is "past matter".

:m:

What exactly does it mean when scientists say the universe is expanding?

It means there something pushing things apart.

I think the universe is getting positively charged due to conversion of photons from electrons. Hence the positive charges repel eachother.

Is that strong enough to create an accelerated expansion of the entire universe? :confused:

I think the universe is contained in an undetectable force field ,that is generated by a magic spell ,cast by one of the gods.
Can you disprove my idea?

lol @ backpedalling

I think the universe is contained in an undetectable force field ,that is generated by a magic spell ,cast by one of the gods.
Can you disprove my idea?
It has to be logical. I cannot see much logic in that. Can you?

It has to be logical. I cannot see much logic in that. Can you?

i say thats the new theory that we should focus our efforts on,


peace,

It has to be logical. I cannot see much logic in that. Can you?

Yes it has to be logical, and many scientists have gone through all the
what ifs, and come with the present mainstream theories, this was just
a demonstration to show that any theory can be proposed but, it is
useless if it can not be tested.
I am not saying these mainstream theories are right, just that they are the
best we have to fit the given data, when we have have masses more data
the theories may change.
But do not hold your breath NASA is more interested in going to mars.

Mars is a little closer.

Mars is a little closer.

Yes but what will it tell us of the universe? going to Mars is just a waste of
resources, its cost could fund many other missions that could give us useful
data, Mars is just an ego trip.

Yes it has to be logical, and many scientists have gone through all the
what ifs, and come with the present mainstream theories, this was just
a demonstration to show that any theory can be proposed but, it is
useless if it can not be tested.
I am not saying these mainstream theories are right, just that they are the
best we have to fit the given data, when we have have masses more data
the theories may change.
But do not hold your breath NASA is more interested in going to mars.
What's wrong with my hypothesis? It's not any less likely then multiverses, is it?

What's wrong with my hypothesis? It's not any less likely then multiverses, is it?

I can not remember the facts, but i think oscillating universe theories run
into entropy problems, i will try to find papers.

This is from Wikipedia.

http://en.wikipedia.org/wiki/Oscillatory_universe

In the simple cases studied by Friedman[1], containing just homogeneous matter and possibly a negative cosmological constant, each "bounce" is a gravitational singularity with infinite density and zero size. It is then a matter of taste whether to extend the solution through the singularities, giving an infinitely oscillating model, or to assume that only one cycle exists. The oscillating model was once popular amongst cosmologists who thought that the singularities could be avoided and so each big bang would be connected to an earlier big crunch: the mathematical singularities seen in calculations were supposed to be the result of over-idealizations (e.g. assuming too much symmetry or neglecting some force), and would be resolved by a more careful treatment, or by an alternative theory of gravity such as Brans-Dicke theory. In this case, as pointed out by Tolman[2], entropy would build up from oscillation to oscillation; according to Tolman this would cause each oscillation to last longer and reach a larger size than the one before, in some sense tending towards a condition of heat death. However, in the 1960s, Stephen Hawking, Roger Penrose and George Ellis showed that singularities were a universal feature of cosmologies with a big bang and that no feature of general relativity could prevent them. Since no "memory" of previous cycles would be preserved, the entropy issue was eliminated, but by the same token there was little reason to postulate cycles before or after the present one. Other measurements suggested the universe is not closed. These arguments caused most cosmologists to abandon the oscillating universe model.

Its possible that all the electrons in the univrese will be used up and that will create a soup of positive ions and ...

well


Is it possible that positive ions can attract photons ?

After all photons originate from electrons.

Its possible that all the electrons in the univrese will be used up and that will create a soup of positive ions and ...

How could all the electrons get "used up?"

How could all the electrons get "used up?"

Actually i dont know but i think that because light is generated from electrons there should be more protons around us each time light is produced. :confused:

Singularity,

Not quite. Whenever an electron moves between the different orbits of an atom, they emit or absorb a photon (depending on whether they are moving to a higher energy orbit or a lower energy one). The net effect is always "0".

As far as decaying goes, protons are the longest "living" subatomic particles and they decay after about 30 billion years. So given that the age of the universe is about 14 billion years, we are about half way through the life of the universe. :cool:


:itold:

Singularity,

Not quite. Whenever an electron moves between the different orbits of an atom, they emit or absorb a photon (depending on whether they are moving to a higher energy orbit or a lower energy one). The net effect is always "0".

As far as decaying goes, protons are the longest "living" subatomic particles and they decay after about 30 billion years. So given that the age of the universe is about 14 billion years, we are about half way through the life of the universe. :cool:


:itold:

It is said that in nuke reactions some matter get converted in to energy. So if we have a very very power Light bulb (or its equivalent) that emits light (without nukes) equivalent to sun. Do u think there will be conversion of matter into energy in that case ?

I'm not sure what you are asking. Do you want a light bulb as powerful as the sun? LOL! :D

Truth seeker.

Cocked up my post in reply to oscillating universe, it ended up on page 5.

:confused:

:confused:

Tell me , when fantastic amounts of energy is converted into light (without nuke reactions), do we loose some matter ?

Tell me , when fantastic amounts of energy is converted into light (without nuke reactions), do we loose some matter ?
I think most all of us have considered this question when we were getting interested in physics. I know I have in the past.

The first thing to think about is how 'energy' is converted into light. Stars, of course, shine mostly through nuclear reactions producing heat. Heated objects give off radiation, but it takes some form of energy to produce the heat, a balancing act as far as the emitted photons (energy) is concerned. The emitted photons can heat other objects, causing them to give up the absorbed energy as new photons, or the photons can be reflected, such as moonshine. So, if a body is not (1) absorbing then re-emitting external photons, (2) reflecting external photons, or (3) does not have an internal process generating heat through energy usage, then how can it emitt photons? It would be a blackbody. If you think about your lightbulb, it is using external energy (electricity) to heat the filament in the bulb.
These are very simplified examples, but I am a simple person. ;)

2inquisitive,

Are u implying that light cannot be generated without destroying some electrons somewhere ?

2inquisitive,

Are u implying that light cannot be generated without destroying some electrons somewhere ?

I'm not even sure what you are speaking of. Electrons emit a photon when they drop to a lower orbital. In a 'cold' atom, the electrons are in their lowest orbital, they cannot drop any further. If the atom absorbes a photon, the electron moves to a higher orbital, then may either emit a photon with the identical energy when it drops back to the lower orbital, or store the absorbed photon as energy which heats the atom. An already 'hot' body will emit photons and cool as it does so, until it is thermally stabilized with its enviroment.

Or are you thinking of 'using' the electrons in an electric current to generate heat?

:confused:

I dont know, but i think when sun emits EM energy, its all the extra electrons that get consumed in production of these photons during the nuclear fusion.

So i was wondering if the universe is getting positively charged and ( repelling ) expanding.

:confused:

I dont know, but i think when sun emits EM energy, its all the extra electrons that get consumed in production of these photons during the nuclear fusion.

So i was wondering if the universe is getting positively charged and ( repelling ) expanding.

The thing to understand is that NO electrons are "consumed" in producing a photon - not even one. The electron drops from a higher energy level to a lower one, releasing energy only in the form of a photon.

In very real sense, you could compare it to water being held in a reservoir. When it passes down through a turbine, generating electricity, and flows out into the river below, non of the water has been consumed. It merely transfered it's kinetic energy as it traveled from one level to another - physically - and nothing was destroyed. Energy was simply converted. It's precisely the same with the electron and it's generating a photon. Energy transformation only.

I already said that the electrons only change orbits. They are not converted to anything. They are not lost. :bugeye:

I already said that the electrons only change orbits. They are not converted to anything. They are not lost. :bugeye:

Were you replying to me or Singularity? My post was a reply to her question since she didn't seem to be grasping what you and everyone else were saying.