Why space is expanding

Originally posted by Aim64C

It could also be a demon that is gobbling up all the light.

We form many, many assumptions about the distant universe that are questionable, at best. We presume physics to be largely the same. It does not have to be this way - what we perceive as similar to our own galaxy may be a completely different physical system operating on mechanics that contact our own on a tangent (the obvious one being the emission of light).

Now - it may be "unreasonable" to do so... but it's also somewhat suspect to believe the universe has a beginning, end, or defined state to begin with. Entire portions of our universe could theoretically be lying in quantum superpositions and their history will be filled in as they are observed (could be a potential explanation for all the magichanical forces out there).

Or - hell - there could be an entire class of physics that we could never begin to hypothesize about until operating across several lightyears or more (just as we wouldn't have really predicted quantum mechanics until we started dealing with electricity, steam, and other concepts that formed our understanding of particle physics... and even then - we didn't predict it so much as it bit us in the ass).

I have no issues with speculating about demons or alternative physics to explain certain phenomena. But we will always have to go back to the basis, which is observation, in order to see if the speculation has any merit. Sure, some of the theories we currently hear from physicists or cosmologists are far fetched. But there is also a lot of evidence out there. You can't just put all hypothesis and ideas on a large pile and claim they are equally likely.

Not convinced.

It's not because I haven't heard or don't understand what you're saying. It's because I find it to be a horribly unsubstantiated conclusion given the evidence.

Why do we expect to see light out there?

What evidence is there that we should expect to find light where we aren't seeing it?

What other explanations are possible?

Why does one explanation without proper mechanical founding become favored over other explanations that make no additional assumptions yet also lack proper mechanical founding?

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

If you have other explanations please share them.

*shakes head*

You're deluded by earthly accomplishments. Most of our accomplishments - while allowing us to progress far beyond our imagination - are little more than creative manipulation of phenomena we largely stumbled across.

We didn't develop nuclear reactors. We simply learned to harness the natural process of spontaneous-cascading fission reactions that occur in nature.

About the only thing we can actually claim as our own development would be the PN junction. Almost everything else was a refining process of what we happened to trip over. Metallurgy, basic electronics, chemistry and biology - the list goes on.

Taking that into account, I believe my perspective on predictions regarding the function of the universe at large is quite pragmatic. For example - that atom was considered, for quite some time, to be a mathematical convenience by many in the scientific community. It worked well for calculating how steam under pressure would behave, but surely that was where the usefulness ended.

I simply think there are phenomena out there that we have no way of anticipating - and they will challenge many of our preconceptions about how the universe "out there" is supposed to work.

Our track record of manipulating things we've discovered is superb. Our track record of actually developing/predicting an understanding of processes from theory.... not so good.

That is just your perception, I see it differently. But thats just a matter of opinion I guess.

Your last sentence is kind of intriguing. You say that our track record is not so good. Not good compared to what exactly? To what you want it to be?

The reference I use is humanity throughout history. And compared to that I think it is unarguable that we are currently showing an extremely good track record.

reply to post by Arbitrageur


"We have demonstrated that it contains "vacuum energy" among other things"

but do we know if what we detect is a fundamental aspect of space itself,, or fluctuations of energy because of the physical variables of the universes interaction with each other?

what do you think vacuum energy means? what causes it to exist? what is it?

reply to post by -PLB-


"It is not assumed that nothing is there ("there" being beyond the boundary of what we can see). We assume there are more galaxies there, its just that the light (radiation) they emit does not reach us yet, or will never reach us at all, no matter how long we wait."

ahh i think i see now,,,, probably because when those farthest galaxies were forming they were moving away from us,, and we were moving away from them,, so even if its light is traveling towards us, we have such a head start in the direction we are traveling,,and we are at such a vast distance,, that the light can never catch up?

Originally posted by Arbitrageur

Originally posted by ImaFungi

Originally posted by Arbitrageur

Originally posted by ImaFungi

Originally posted by -PLB-
from this article: en.wikipedia.org...

ok so it is then thought/assumed that this region is the bound or edge of the universe? nothing exists beyond the point at which we can see no further?

You obviously didn't read the link. Give it a try.

ok read the first section of the link,,.,.,. If there was light beyond the final point we can detect light, in principle we would be able to detect it,, so we assume nothings there? is that the point?

No we don't assume nothing is there. It's part of our standard model that there was a dark period after the big bang where lots of stuff was there but it wasn't visible.

Look at the "Dark Age" in this illustration:

Lambda_cdm
We assume something was there but it wasn't giving off light yet, which is why it's called the dark age.

this pictorial analogy is not completely accurate to reality either,, in the way that ( unless im wrong) I dont believe it is presumed the big bang expelled/expanded its contents like an upward shooting geyser,, did it? if it did not,,, would that image be more appropriate if the expansion was shown completely surrounding the begging of time starting point?

I understand it is attempting at showing the upward ( forward) travel through time,,

Originally posted by ImaFungi
ahh i think i see now,,,, probably because when those farthest galaxies were forming they were moving away from us,, and we were moving away from them,, so even if its light is traveling towards us, we have such a head start in the direction we are traveling,,and we are at such a vast distance,, that the light can never catch up?

A bit like that. But we aren't really "moving" away from them, instead the distance between us and them is increasing. That may seem like the same thing but it is not. We are pretty certain that actual speed of movement between two objects can never exceed the speed of light. However, that is exactly what is happening to those very distance galaxies. They "move" faster away from us than the speed of light. So their light can never reach us. The explanation is, they are not really moving, but the space in between is expanding.

Originally posted by -PLB-

Originally posted by ImaFungi
ahh i think i see now,,,, probably because when those farthest galaxies were forming they were moving away from us,, and we were moving away from them,, so even if its light is traveling towards us, we have such a head start in the direction we are traveling,,and we are at such a vast distance,, that the light can never catch up?

A bit like that. But we aren't really "moving" away from them, instead the distance between us and them is increasing. That may seem like the same thing but it is not. We are pretty certain that actual speed of movement between two objects can never exceed the speed of light. However, that is exactly what is happening to those very distance galaxies. They "move" faster away from us than the speed of light. So their light can never reach us. The explanation is, they are not really moving, but the space in between is expanding.

yea that just makes no sense....... so our galaxy is stationary compared to all other galaxies,,, no galaxy moves.... but the space between point a and b becomes a larger distance,,,, its only logical to assume that point a or b has changed its relative distance which is the deffiniton of movement,,, this is why i am skeptical of the things i have thus far been skeptical of..,.,.,

the only reason we think they are moving faster then light is redshift? how do we perceive they are moving faster then light?

Originally posted by ImaFungi
yea that just makes no sense....... so our galaxy is stationary compared to all other galaxies,,, no galaxy moves.... but the space between point a and b becomes a larger distance,,,, its only logical to assume that point a or b has changed its relative distance which is the deffiniton of movement,,, this is why i am skeptical of the things i have thus far been skeptical of..,.,.,

Of course the way nature works isn't supposed to make sense to us . Movement may be defined by a change in relative distance between two objects, but that does not mean that all change in relative distance between objects is movement.
In the same way that a Ford is defined as a car, but not all cars are a Ford (sorry for the cheesy analog).

When you assume that there is actual movement, it would mean that the objects were accelerated by an active force. So beside the fact that speeds greater than c contradicts our current understanding of physics, you will also have to explain this force. You won't get a step further.

the only reason we think they are moving faster then light is redshift? how do we perceive they are moving faster then light?

We use redshift to determine the distance of objects. Light coming from a certain distance corresponds with a certain redshift. The farther away the object, the larger the shift. This also correlates with the brightness of the objects (with exception of quasars).

Since we do not detect objects beyond a certain red shift level, we can come to the logical conclusion we can not detect objects beyond a certain distance. Their light does not reaches us. It either means the light is still under way, and will eventually reach us, or it means that the distance between us and the object is increasing at such a rate that it will never reach us. The net speed of the light it is emitting to us is still away from us. (think of shooting a water pistol from the back of a car, the water will never move backwards, just moves slower forward).

Although this logic is valid, it may not be sound, as we do not know for fact if our assumptions are completely correct. But the evidence to support them is there.

reply to post by -PLB-


"When you assume that there is actual movement, it would mean that the objects were accelerated by an active force. So beside the fact that speeds greater than c contradicts our current understanding of physics, you will also have to explain this force. You won't get a step further. "

so no matter has moved since the beginning of the big bang? then in a pico second after the big bang the galaxy would have to have formed as they are now to be as a raisin in the expanding loaf of universe,,,,
if galaxies dont move how can a galaxy collide with another?

I dont nessecarily believe galaxies are accelerated,, i believe it is a visual doppler affect,,, of as we are rotating and revolving and receiving the light information from far away galaxies the galaxies may be moving away from us,, and then next time we measure they have moved even farther,,, but we have also moved,,, so i think this exponential doubling is why it appears like they are accelerating over time,,,,.

you believe that galaxies dont move? so would that mean black holes are kind of like an anchor? and maybe the revolving matter ( stars and planets) revolving around a black hole is the engine process which churns out "dark energy, dark matter, space" and which creates the disturbance in space time which increases distance between galaxies which is perceived as spatial expansion?

reply to post by -PLB-


" The net speed of the light it is emitting to us is still away from us. (think of shooting a water pistol from the back of a car, the water will never move backwards, just moves slower forward). "

but doesnt a star ( and galaxy) spin? wouldnt that mean that all of its light every light second would be shot out in every direction at all times? does this distribution in relation to spin have any affects on the way light travels or its path? or the second light photons come into existence from the relative point they do,, they shoot exact! straight ahead and seemingly only curve near massive bodies because of gravity? would the sun or galaxies gravity not effect the straight shot escaping newly created light?

Originally posted by ImaFungi
"When you assume that there is actual movement, it would mean that the objects were accelerated by an active force. So beside the fact that speeds greater than c contradicts our current understanding of physics, you will also have to explain this force. You won't get a step further. "

so no matter has moved since the beginning of the big bang? then in a pico second after the big bang the galaxy would have to have formed as they are now to be as a raisin in the expanding loaf of universe,,,,
if galaxies dont move how can a galaxy collide with another?

Expansion does not make is impossible for movement to happen. So there can both be expansion and movement.

I dont nessecarily believe galaxies are accelerated,, i believe it is a visual doppler affect,,, of as we are rotating and revolving and receiving the light information from far away galaxies the galaxies may be moving away from us,, and then next time we measure they have moved even farther,,, but we have also moved,,, so i think this exponential doubling is why it appears like they are accelerating over time,,,,.

Without acceleration the red shift (or "visual doppler effect) will not change. It will remain the same. Just the amplitude (or intensity) decreases, but not the frequency.

you believe that galaxies dont move? so would that mean black holes are kind of like an anchor? and maybe the revolving matter ( stars and planets) revolving around a black hole is the engine process which churns out "dark energy, dark matter, space" and which creates the disturbance in space time which increases distance between galaxies which is perceived as spatial expansion?

I do believe that galaxies move. Like I wrote above, expansion does not exclude movement.

Originally posted by ImaFungi
but doesnt a star ( and galaxy) spin? wouldnt that mean that all of its light every light second would be shot out in every direction at all times? does this distribution in relation to spin have any affects on the way light travels or its path? or the second light photons come into existence from the relative point they do,, they shoot exact! straight ahead and seemingly only curve near massive bodies because of gravity? would the sun or galaxies gravity not effect the straight shot escaping newly created light?

Spinning does not affect the movement direction of particles that are shot away. It only has an effect on their initial direction. Once the particles are on their own, they will not longer have any rotational movement. They will go straight ahead.

Gravity of other objects can indeed have an effect on the path of the particles. This is called gravitational lensing.

reply to post by -PLB-


"I do believe that galaxies move. Like I wrote above, expansion does not exclude movement. "

If galaxies do move,, then why does space have to expand for the distance to increase between two galaxies? ( i think i figured out the answer but i dont know if i like it,,,,, because you believe all the galaxies surrounding us are moving/expanding directly away from us,, the other galaxies relative to our position in the direction we are heading ( away from the galaxy we are observing) must also be moving away from us,, and same for all galaxies at the same time,,, so by only looking at 2 galaxies ours and the one we are observing,, we can not just say we are moving away from this galaxy because then we may be moving towards many other galaxies in the opposite direction,, so those galaxies must also be moving away from us, and we also must be moving away from it,,,,,. ?!?!?!?!

so the real reason you believe space itself "expands" is because light takes longer to travel from its source to us then it did in the past? and this isnt due to the galaxies "moving" further apart? because then the light speed constant would have to change? so space carried the light at its normal speed, but it was space itself that was expanding to keep light up to its constant speed to make it to our observation in the expected and demanded constant time?

reply to post by -PLB-


Could the big bang have began with spin? creating a sort of vortex of revolution and rotation of the entire universe, and possibly and potentially cause galaxies to travel in orbits and revolutions around other clusters?

this could also be why redshift appears to be a galaxy flying away from us acceleratingly, but it could really be coming into our view,, measured,, passing across our view, measured,, and then zip out of view and in reality not traveling faster away from us,, but traveling eventually around us, and us it? like a shooting star streaks across the sky, a visual doppler affect?

Originally posted by ImaFungi
"I do believe that galaxies move. Like I wrote above, expansion does not exclude movement. "

If galaxies do move,, then why does space have to expand for the distance to increase between two galaxies? ( i think i figured out the answer but i dont know if i like it,,,,, because you believe all the galaxies surrounding us are moving/expanding directly away from us,, the other galaxies relative to our position in the direction we are heading ( away from the galaxy we are observing) must also be moving away from us,, and same for all galaxies at the same time,,, so by only looking at 2 galaxies ours and the one we are observing,, we can not just say we are moving away from this galaxy because then we may be moving towards many other galaxies in the opposite direction,, so those galaxies must also be moving away from us, and we also must be moving away from it,,,,,. ?!?!?!?!

We are moving away from practically all galaxies out there. Only galaxies that are very close can show different behavior, like Andromeda.

But I do think you get the idea. If all galaxies were actually accelerating away from us, it would mean that we are at the exact center of their origin from where they are accelerating away from. That does not sound likely. It would also mean that speeds greater than c are possible, contradicting our current understanding of physics.

Of course we are not dealing with absolute facts, but evidence strongly suggests expansion of space to be the case.

so the real reason you believe space itself "expands" is because light takes longer to travel from its source to us then it did in the past? and this isnt due to the galaxies "moving" further apart? because then the light speed constant would have to change? so space carried the light at its normal speed, but it was space itself that was expanding to keep light up to its constant speed to make it to our observation in the expected and demanded constant time?

This is not the reason that I believe space is expanding, though I must say I don't really understand what you are saying here.

Originally posted by ImaFungi
Could the big bang have began with spin? creating a sort of vortex of revolution and rotation of the entire universe, and possibly and potentially cause galaxies to travel in orbits and revolutions around other clusters?

this could also be why redshift appears to be a galaxy flying away from us acceleratingly, but it could really be coming into our view,, measured,, passing across our view, measured,, and then zip out of view and in reality not traveling faster away from us,, but traveling eventually around us, and us it? like a shooting star streaks across the sky, a visual doppler affect?

Spin can be measured. An inertial frame of reference can not be spinning.

Originally posted by -PLB-

Originally posted by ImaFungi
Could the big bang have began with spin? creating a sort of vortex of revolution and rotation of the entire universe, and possibly and potentially cause galaxies to travel in orbits and revolutions around other clusters?

this could also be why redshift appears to be a galaxy flying away from us acceleratingly, but it could really be coming into our view,, measured,, passing across our view, measured,, and then zip out of view and in reality not traveling faster away from us,, but traveling eventually around us, and us it? like a shooting star streaks across the sky, a visual doppler affect?

Spin can be measured. An inertial frame of reference can not be spinning.

an inertial frame of reference what do you mean by that?

I was just wondering if its possible that the moment the big bang began,, it could have burst out wards with a spin,, and thinking that could this have had an effect on what was to follow,, maybe intertwining all the energies, and keeping the universe from flinging completely apart, like a tornado, hurricane or galaxy,

i dont know anything about space. but i was allways taught space is a vacuum.
a vacuum cant expand.

Originally posted by ImaFungi
an inertial frame of reference what do you mean by that?

An inertial frame of reference is a frame of reference in which our physics work without adjustment. If the universe was spinning, we would need to adjust for it. Just like we need to adjust for the spinning of the earth for our physical laws to work on earth. That said, the error is so small that it can be neglected in most cases. But it is measurable. (also see WikWikipedia. About a spinning universe it says:

To illustrate further, consider the question: "Does our Universe rotate?" To answer, we might attempt to explain the shape of the Milky Way galaxy using the laws of physics.[11] (Other observations might be more definitive (that is, provide larger discrepancies or less measurement uncertainty), like the anisotropy of the microwave background radiation or Big Bang nucleosynthesis.[12][13]) Just how flat the disc of the Milky Way is depends on its rate of rotation in an inertial frame of reference. If we attribute its apparent rate of rotation entirely to rotation in an inertial frame, a different "flatness" is predicted than if we suppose part of this rotation actually is due to rotation of the Universe and should not be included in the rotation of the galaxy itself. Based upon the laws of physics, a model is set up in which one parameter is the rate of rotation of the Universe. If the laws of physics agree more accurately with observations in a model with rotation than without it, we are inclined to select the best-fit value for rotation, subject to all other pertinent experimental observations. If no value of the rotation parameter is successful and theory is not within observational error, a modification of physical law is considered. (For example, dark matter is invoked to explain the galactic rotation curve.) So far, observations show any rotation of the Universe is very slow (no faster than once every 60·1012 years (10−13 rad/yr)[14]), and debate persists over whether there is any rotation. However, if rotation were found, interpretation of observations in a frame tied to the Universe would have to be corrected for the fictitious forces inherent in such rotation. Evidently, such an approach adopts the view that "an inertial frame of reference is one where our laws of physics apply" (or need the least modification).

I was just wondering if its possible that the moment the big bang began,, it could have burst out wards with a spin,, and thinking that could this have had an effect on what was to follow,, maybe intertwining all the energies, and keeping the universe from flinging completely apart, like a tornado, hurricane or galaxy,

I don't think so. From what I understand the rotation of the universe (if there is any) has little effect on anything.

Originally posted by IblisLucifer
I have to ask the question as to why space is expanding,
you can't just create more space
So in order for objects to be moving apart and space between objects to be increasing, The object must be getting smaller and taking up less space then they did previously.

The notion of an "expanding" space is as nonsensical as the idea of an expaning of time. Space and Time are metaphorical structures more appropriate to the study of semiotics and language than to physics and cosmology/cosmogony. They are ideational/conceptual constructs. Of course physicists would like to "have their way" with them: with these two conceptual ideas, but soon enough they will have been upended by better minds schooled in superior art of philosophy and its closest relative - metaphysics.

reply to post by Vitruvian


In fact, space is very real and can be measured precisely. I am not sure where you got the idea that it is just a conceptual idea, in physics is certainly is not.