expanding universe

[johan01]

If space is being created with the expanding universe, can it be destroyed as well.

[Klaynos]

Space is not being created.

 

Space is expanding.

 

It could also contract, but this AFAIK has not been observed.

[johan01]

this is confusing , explain the difference between expanding and creating new space.

 

 

a. We know that the distance between two points has increased.

 

You say space is expanding ( similair to stretching ?) I.E no " new space being created". Is this correct?

 

If so then everything occupying that space is stretching as well. So then the object that we measure this distance with , will stretch in proportion to.

Then the ratio would stay the same. The how can we observe "a" above.

[gonelli]

I'm not an expert on the topic, but my understanding of the universe expanding is that matter is becoming more spread out, not being streched.

 

Similar to how gas being stored in a container will expand if the volume of the container increases. The physical size of the gas particles will not change, but the average distance between them does increase.

[johan01]

i agree with you gonelli.

 

if i draw a continous line on a balloon, and then i blow it up further.

The distance between its ends has increased , and new points on the balloon ie "space" has emerged between the ink, which were not there origionally.

This is my interpretation .

[Klaynos]

Space expands on a large scale, over shorter distances the expansion is overshadowed by other attractive interactions, mainly gravity, but over very short distances EM forces...

[johan01]

large spaces or not

 

this is confusing , explain the difference between expanding and creating new space.

 

if expanding space only affects large space , why does light / photons have redshift?

[Mr Skeptic]

if expanding space only affects large space , why does light / photons have redshift?

 

Yes, and what about the law of conservation of energy? Redshifted photons have less energy than before, where does that go?

[johan01]

good point MR Skeptic

Off the subject a bit ... on photons , do you believe that photons could have a mass , and we have still not being able to measure it yet.

 

Because if this is the case , then light would not be the upper limit velocity at which information could be transmitted.

[Klaynos]

Creating implies something new is entering into the universe, whereas expanding is just the same thing getting bigger... ajb might be able to explain this more mathematically, my knowledge of the maths is very limited in this case.

 

Photons are massless. Relativity shows us anything travelling at the speed of light must be massless, and we've exceptional experimental evidence that photons travel at the speed of light.

[Mr Skeptic]

Klaynos, photons travel indistinguishably close to the speed of light, and have a rest mass indistinguishable from zero. To say that they are measured to be massless would require measurements of infinite precision. The best evidence that photons are massless is the predictions of particle physics that photons are massless.

[Klaynos]

Klaynos, photons travel indistinguishably close to the speed of light, and have a rest mass indistinguishable from zero. To say that they are measured to be massless would require measurements of infinite precision. The best evidence that photons are massless is the predictions of particle physics that photons are massless.

 

I make no comment as to a measurement of mass, just what relativity tells us should be true, and that we measure the speed of photons to an exceptionally accurate value.

 

Also IIRC electrodynamics shows us that photons must travel at c, therefore from electrodynamics and relativity you can safely say that photons have no rest mass.

[Martin]

large spaces or not

 

this is confusing , explain the difference between expanding and creating new space.

 

if expanding space only affects large space , why does light / photons have redshift?

 

these are reasonable questions to be asking. I hope they aren't the only ones you ask and that you have got some on a more practical observational level as well.

 

questions on a philosophical or foundational level don't always have satisfactory answers because of the subjective/semantic element, but I will try something with you.

 

This is an exercise. Don't think of space expanding or contracting. Instead of space, think of a bunch of relationships. These relationships are changing. That is all.

 

For a day or so, make yourself not say these words "space expands". Instead, only say these words: "distances change, some distances increase."

 

See if this makes any difference.

============================

 

This may seem to you like a pointless mental exercise. So I will try to explain.

 

Things can be created and destroyed. Things can expand and contract. Space is not a thing. There is no space, there is only geometry---a bunch of geometric relationships.

 

We have learned that geometry is dynamic. The distances between stationary objects are constantly changing. The gravitational field is nothing else than geometry itself. It is affected every time you move some matter around. We have no right to expect the distance between stationary objects to remain always the same.

 

Relationships cannot be created or destroyed or expand or contract, they simply are, as long as the objects are there to be related, and they change.

 

This is an oversimplification. But try thinking that way for a day or so and see if it make a difference.

[johan01]

"Relationships cannot be created or destroyed or expand or contract, they simply are, as long as the objects are there to be related, and they change."

 

i disagree with this statment , i would like to ask you a question .

 

There are two approaches to create relationships , First observe then satisfy the observation.

Or theorize then try and prove ( observe) your theory.

 

 

One is to understand and be in touch with the observable universe using our imagination , and derive a relationship to explain what we are experiencing . These relationships are obviously always improving as we go. But they are never always there etched in stone.

 

Einstein proved that the universe was expanding , but he could not observe this , so he introduced the cosmological constant to satisfy the observed emperical data of the day.

 

Hubble observed this but did not have the imagination to explain it with a relationship.

 

 

I say question what is fact today , the theorems that are etched in stone , are not forever. Like you said so long as everything is changing , nothing is certian.

 

All our paradoxes , are due to incomplete theory. There is a theory of everything but

we will never measure it, until we have experienced it.

 

If photons are massless , why are they drawn into black holes , and why do they show symtoms of energy loss during long stretches of travel across our great voids of space.

 

if C is the upper limit of velocity, why does it take so long to move information across a galaxy , never mind between galaxies.

 

There may be more exotic lighter particles , we dont know , but if it takes 14 billion years to establish that the universe is expanding , mabey we are the goldfish looking at world through our bowl , which is distorting all those tired photons that have been gravitationally "lensed" out of context.

And now we have all these exotic theorems that "do" preditc what we observe, but do not explain what is really happening.

 

As einstein said " imagination is more important than knowledge". Often I ask a child

what their definition of time, space or matter is , and you know their simple explanations are more meaningful than the pillars and theorems , explaining our 4 fundamental forces , that we are so rigorously trying to quantize

 

I believe einstein was once asked how he came about his great e= mc^2.

And his answer was , for many years he tried to imagine what you would experience if you hitched a ride on a moving photon.

He said he eventually came to the conclusion that time would stop. What a great deduction from his understanding of his observations.Eventually after a long time i agreed with this, because i experienced his reasoning. and his great theorems that he could derive from imagination and observation. well that is what made him so valuable to the human race.

 

I say there are lighter particles than photons , yet to be discovered , and the upper limits of velocity , will yet again be challenged , And when these velocities are realized , " eureuka" 14 billion light "years" will be meaningless , and the definition of an "expanding" universe with respect to our so called "empty space" will yet again change when time in its purest form is better understood.

[Martin]

...

As einstein said " imagination is more important than knowledge". Often I ask a child what their definition of time, space or matter is , and you know their simple explanations are more meaningful than the pillars and theorems, explaining our 4 fundamental forces , that we are so rigorously trying to quantize...

 

I say there are lighter particles than photons , yet to be discovered , and the upper limits of velocity , will yet again be challenged , And when these velocities are realized , " eureuka" 14 billion light "years" will be meaningless , and the definition of an "expanding" universe with respect to our so called "empty space" will yet again change when time in its purest form is better understood.

 

This is inspiring, Johan, but difficult to answer constructively. I see no way to respond, in terms of current theory, that would do you any good.

 

In my post #13 I merely suggested a simple exercise. Instead of thinking of space as a substance or material, think of it as a list of spatial relationships---a table of distances.

 

That's all. You can try it or not as you choose.

Edited December 9, 2008 by Martin

[johan01]

hi martin

 

I admit , i find it hard to exercise your view on space geometry and relationships as only that. Mabey that is all that it is , after all that is said and done.

 

But I have thought about space, time and matter for far to long , for it only to be a geometric relationship for me. It is a quest for truth , and all the rest is "stamp collecting".

 

can i now entertain you with an exercise .

 

 

"Imagine" a volume of empty space ( pure vaccum) existing without , no form of energy occupying that " space" , i.e no photons , no exotice particles , "no dark energy" whatsoever and at what temprature? Well we must assume 0 kelvin not so?

 

This might sound like a contradiction.

Thats because it is !

 

But then let us assume it does occur in our universe ,and can be isolated by coordinates , whether in deep space or in a lab for that matter . Because that is our understanding of a vaccuum to date , and supposedly this volume of coordinates are " expanding" acoording to the CBR and redshift data accumalated .

 

this small vaccum would mean ther is absolutely no event ( time) occuring in this isolated volume . It is eventless , massless , heatless.

 

But heres the point , IT IS THERE, according to us . If I walk into this " geometry" of volume , IT EXISTS around me . And tomorrow there is a bigger space ," i can now go to two places where there was only one yesterday" , i can move to coordinates where i was not yesterday.

 

But wait , nothing has changed since yesterday! No event has occured since yesterday in my massless , heatless , energyless volume of "coordinates" NOTHING OCCURED.

 

This is the paradox to me! Something is wrong.

 

Our definition of vaccum is meaningless, just a relationship to "nothing".

Our assumption of " empty space" existing without some form heat, energy/ matter is implausable ,and time could not progress there without change there.

Hence we might as well say that volume of coordinates does not exist, since how can you box "nothing" into coordinates. if you cannot experience it.

 

Our definition of empty space is flawed.

just like the conservation of mass/energy . Space cannot exist alone, of coursre then it will rip you up , like our infamous big rip theory..

 

One cannot have space without a purpose.It is not the carrier of the particle (whether it be a photon, or Higgs boson) it is the creator of the particle.

 

It comes back to my assumption. Is there any volume in the universe where there is no

heat, photon, particle or information. If there is and there may be. But then it is not space at all , it does not have a coordinate. it is like a hole in our ozone.

 

Or for a better analogy a black hole. Where space has broken down beyond the plank relm . Whithin that event horizon there is no energy , matter or space.

 

My analogy of a black hole is my clue to space quantization and the destruction of space .

 

My initial post

 

" if space can be created , can it be destroyed" - i do believe so , and this is why i say so.

 

 

imagine all the universe is a sphere of solid concrete.Full of energy and matter that likes to attract eachother. But energy can only condense to a certian quantum space and then it must "leave" since the energy itself is changing the coarsness of this space quantization around itself and even within itself , the very coordinate in space that energy is occupying is quantized to a different energy level.

 

When this condensation of energy becomes large the space "tears". The result is Now within our concrete sphere we have an "air bubble" , just like the outside of the sphere - which relates to "no more space there" , in the bubble that is.

 

As energy approaches this bubble , it starts to condense due to the space quantization levels for energy occupying it , these quanta get smaller .Until the energy eventually has to leave in the form of Gamma /Xrays and other exotic particles, at very high energies, since it cannot exist in these space quantization levels.

Similair to the particle in a box analogy. So as energy approaches the event horizon at the black hole , space becomes less and less , so it has to leave.

Because at this horizon there is no more space at all , just a bubble in our concrete universe.

 

 

All this is in my imagination , and now you may ask why can i not sleep!

[Gilded]

There is no perfect vacuum. Space has a certain energy and properties associated with it, so it isn't nothing. Nothingness is an abstract philosophical concept.

[johan01]

absolutly ... it is an energy resevoir where all other energy/matter jumps in and out from when they are unstable and isolated.

[Gilded]

absolutly ... it is an energy resevoir where all other energy/matter jumps in and out from when they are unstable and isolated.

 

I have no idea what you're talking about but I was mostly referring to vacuum energy.

[Mr Skeptic]

It comes back to my assumption. Is there any volume in the universe where there is no heat, photon, particle or information.

 

There isn't. First there is background radiation -- the cosmic background radiation, or the radiation from any box that is placed around it (which there will be, unless you can get a box at 0 Kelvin which is impossible). Then there are virtual particles, though I don't know if those are related to the background radiation or intrinsic to space itself.

 

And even if there were totally empty space, you could observe things on either side of the empty space to tell if it is expanding.

[johan01]

"And even if there were totally empty space, you could observe things on either side of the empty space to tell if it is expanding. "

 

to observe on either side of empty space , would not tell you if its expanding , the energy you are observing on either side could be moving apart, ie different coordinates to where they origionally where, but the space could be exactly the same as it was before.

 

the point that i was trying to make is , that space , no matter how far or dark it looks. cannot be empty of energy, not even 1 cube of planck space. because it would not exist.

 

and at the event horizon of a black hole .. space has a boundry , like the edge of our universe, but only here it has been torn apart by high energy densities. where at the edge of our universe it is an inverse process.

[ajb]

Pls read that it's intersting

 

This link is not appropriate for this forum.

 

Moderators please...

[north]

Space expands on a large scale,

 

I disagree

 

space does not expand

 

just the space between objects expands

 

further;

 

space and the Universe will expand only if there is an increase in energy and/or matter in the Universe

[johan01]

"just the space between objects expands"

 

is there space between objects?

would it be true to say that at every point between two objects/ matter/ energy / photons. is another point with an "object/ matter/ energy / photon". and this is true for all the universe as we know , except mabey for the singularity at the black hole.

 

 

like between any 2 rational numbers that are different , there exists another rational number.

[north]

"just the space between objects expands"

 

is there space between objects?

 

why would you ask this question ?

 

what is your basis for this question ?

 

or why does this question of yours make sense to you ?