Space Ends

[Bettina]

Well you know that galaxies are moving away from each other... but what are they moving into or towards? The next galaxy and so on.. in the end you reach a 'edge galaxy' which is expanding into 'new space'... this 'new space' is constantly being added to the universe' date=' hence the universe is expanding.

 

 

Dark matter is 'missing matter' from the universe... [i'](different conversation!)[/i]

Dark energy is what you are referring to and is a kind of hidden energy. Dark energy is hypothetical form of energy which has a negative pressure. The result of dark energy is like having a force acting in the opposite direction to gravity, ie. the energy that keeps the universe expanding.

And no, cosmologists do not fully understand dark matter/energy.

 

"New space" ? I don't think thats right. I thought it was the same space that is just expanding like a balloon. I read somewhere that it was the dark energy that was thought to be causing this expansion and no new space is being created.

 

Bettina

[Martin]

...if they were moving (thru a static nonexpanding space) then some would have to be moving faster than the speed of light to make all the observational data fit together. this would violate Special Relativity!

 

That's ok with me.

 

J5 I am not an arguer. We need to get someone with more moral authority to discuss Special Rel with you. For me it is like ApplePie, where it is applicable, I cannot imagine questioning it. it is like Coquina here at SFN, if you know her.

 

I actually can imagine very slight modifications, in the parts per zillion, of Special Rel

so I can imagine a very very high energy gammaray photon catching up with and passing a lower energy photon, but only over millions of years

 

But some of those galaxies are receding at 20 times the speed of light. I cannot imagine two things in relative motion where one is going past the other at 20 times the speed of light.

 

So if violating SR is OK with you I have no tools with which to carry on discussion. it is outside my ken.

 

for the world to make sense to me I have to distinguish between two kinds of speed. there is ordinary relative motion speed (one thing going past another at a certain speed < c)

and there is RECESSION speed which is a rate of increase in the distance to something far away. it is already far away and the distance to it is increasing at a certain rate and that is the recession speed. and it does not have to be <c and SR is only about local coordinates so it does not apply to that, so it is not violated

[Johnny5]

SR is only about local coordinates so it does not apply to that, so it is not violated

 

What does that mean exactly, that it applies only to local coordinates?

[zazzzoom]

space does not expand

 

space ends

that way space has a shape

and that shape moves from one shape to another shape

[Johnny5]

space does not expand

 

space ends

that way space has a shape

and that shape moves from one shape to another shape

 

Space can't end.

 

The simplest model of space is this.

 

Space is infinite in all directions.

Space is a true vacuum.

It has no inertia.

It has no electrical impedance.

It's temperature is absolute zero.

Somewhere in it, is the center of mass of the universe.

Space cannot stretch, it cannot bend, it cannot expand, it cannot have properties.

And lastly, it is three dimensional.

 

In over two thousand years there hasn't been a simpler model.

[Macroscopic]

Originally posted by zazzzoom

space does not expand

 

space ends

that way space has a shape

and that shape moves from one shape to another shape

If you had any idea what you were talking about, you would back it up with some reasoning. Before talking about the shape of the universe, explain my previous post:

Originally posted by Macroscopic

A shape is something that exists in space. Space can not have a shape because that would imply that something exists outside of it, and you have said you don't believe that. Your 'logic' contradicts itself, and doesn't make any sense.

[zazzzoom]

space ends and it has a shape

[Martin]

"New space" ? I don't think thats right. I thought it was the same space that is just expanding like a balloon.

 

I agree with Bettina's notion of it.

 

and maybe we can even abstractify and think of the AREA of the balloon that is expanding

(so that what we have in mind as space expanding has no hint of rubber in it, no material)

 

space expands like the surface area of a balloon (but, just to avoid confusing anybody) space is not like rubber balloon material, it is not any kind of material at all

 

maybe it is just a vast sum of geometric relationships---a plethora of angle and proximity relations----maybe someday that will be schematized as a network of somekind. but the important thing is not what mathematical entity one uses to represent space, the important thing is the dynamic GEOMETRY of it

 

it may not be of any substance, yet it has shape, lightrays travel along its geodesics, SO IT MUST HAVE GEODESICS. and they are curved by things. and the curving constantly changes as things move.

and the inner angles of each triangle are always adding up to something different, more or less than 180 degrees, and that is always changing.

 

so even though space is, as far as we know, perfectly abstract and insubstantial, yet it must be able to carry a dynamic changing geometry.

 

 

J5 and Bettina, this is a very funny conversation, how it is punctuated by a dull thud every now and then when a voice says space must end.

actually I agree with so and so that it has shape---that is very important---but Riemann showed how space can have shape without having any borders, it does not have to stop anywhere in order to have shape.

He gave us a gift that the Greeks didnt think of.

[Johnny5]

space ends and it has a shape

 

Even if what you say were true, you could not deduce it logically, nor is it inferrable emprically, so the fact would be forever unverifiable by you, or alternatively forever unknowable by you.

 

At any rate, what you said is not fact.

[zazzzoom]

space ends

that way space has a shape

 

think space without any matter or energy in it

 

you could find space has a shape and that shape moves from one shape to another shape

[Johnny5]

 

so even though space is' date=' as far as we know, perfectly abstract and insubstantial, yet it must be able to carry a dynamic changing geometry.[/quote']

 

Do you think there could be another explanation, which preserves the concept of vacuum, yet explains what we observe?

[Martin]

so even though space is' date=' as far as we know, perfectly abstract and insubstantial, yet it must be able to carry a dynamic changing geometry.[/quote']

Do you think there could be another explanation, which preserves the concept of vacuum, yet explains what we observe?

 

sure but in all modesty who is going to think of the mathematical model?

 

Gen Rel gets things right out to many decimal places accuracy

 

(the gravitational effect on atomic clocks, the slowing of binary pulsars observed over decades)

 

gen rel is uncanny

 

but if you only want a kind of general explanation, and dont care about accurate prediction, then you can go back to newton's absolute unbending space and time

 

and someday someone may invent a new theory that has the features you desire and also predicts observational numbers as well or better than Gen Rel. this is always possible.

 

however Gen Rel has beaten all its competition for 90 years of intense creative ferment in physics

 

so my intuitive suspicion is that when they get a new theory IT WILL HAVE A DYNAMICALLY CURVING GEOMETRY TOO

that is, we are probably never going back to a rigid foursquare geometry

 

and that is kind of Riemann's gift, from back in 1854 or so, when Gauss told him to give his talk on geometry instead of the one on electricity, and even though it seems as if we never progress beyond where the Greeks guessed, yet very gradually we do surpass them, brilliant though they were.

[Johnny5]

What about, a vacuum filled with a sea of particles something like this, some kind of particle web, like a spider web or something like that.

 

Then its not the sun curving the geometry of space, which makes the earth follow its path around the sun, instead the sun is compressing the particles, and the earth is moving through a stream, taking the path of least resistance. i am just trying to come up with some explanation other than a curved vacuum.

 

 

So that what Einstein viewed as a warping of space, was more like umm, our ocean, and solid objects creating currents, and density changes, something like a medium.

 

The universe cannot all be empty vacuum, and it cannot all be solid matter.

 

One problem which I have always had, is figuring out how two particles, separated by pure vacuum exert a force upon one another.

 

Action at a distance.

 

Yet it must be possible on some level.

 

I wish someone else had the answer, its easier to learn what someone else knows, than to figure things out for yourself.

 

The fundamental difference between being in the ocean, and being in outer space, is that i can swim under the water, but the same body movements in space, wouldnt get me anywhere.

 

Doesn't anyone have another alternative to GR, or at least an alternative to how GR is interpreted???

 

Even if I understood the math, I would still have conceptual problems with it.

 

There are two models, one of which is probably right.

 

In between planets and galaxies and such, is pure vacuum, and gravitational force is action at a distance.

 

The other is that the region of space in between two planets isn't really vacuum, instead its just matter as well, only extremely less dense matter.

 

And if you zoom in on it, at some level you will find regions of true pure vacuum.

[crzykllrghst]

I'd have to say that I believe that the universe is expanding

[crzykllrghst]

but just to get this out there I am a High School Student in my 3rd year. So my being here was suggested by my Chemistry(who is an astronomy buff and he runs astronomy club, which I belong to) teacher, he tells me I've a great scientific mind. I'm here to learn more then debate

[Bettina]

but just to get this out there I am a High School Student in my 3rd year. So my being here was suggested by my Chemistry(who is an astronomy buff and he runs astronomy club, which I belong to) teacher, he tells me I've a great scientific mind. I'm here to learn more then debate

 

There are good people here....just give it a little time....

Bettina

[Martin]

Here are two good online cosmology calculators I was going to post link to

 

Siobahn Morgan's

http://www.earth.uni.edu/~morgan/ajjar/Cosmology/cosmos.html

 

and Ned Wright's

http://www.astro.ucla.edu/~wright/CosmoCalc.html

 

homepages for Morgan

http://www.earth.uni.edu/smm.html

and Wright

http://www.astro.ucla.edu/~wright/intro.html

 

To use Siobahn's calculator put Lambda = 0.73

Omega = 0.27

H = 71 (or leave her default value of H = 70, nearly the same)

those are the dark energy and the matter densities as fractions of rho crit,

and H is the present value of the Hubble parameter

 

then put in any redshift z,

like z =1 or 3 or 10 and it will tell you how far away the thing

was when it emitted the light we are now getting from it

and how far away it is now

and how fast it was receding then

and how fast it is receding now, at the present moment.

 

Have to go! be back later and can explain if anyone is curious about the calculators.

[Macroscopic]

Originally posted by zazzzoom

space ends and it has a shape

Did you read my post? Are you capable of making a logical argument?Are you capable of addressing other people's arguments? Do you have any idea what you are talking about? If the answer to any of those is 'yes', then stop your preaching, adress people's arguments with your own LOGICAL arguments, and learn how to use some grammar. Seriously.

[mustang292]

use some grammar. Seriously.

use some grammar, seriously.

[Macroscopic]

Originally posted by mustang292

use some grammar, seriously.

I do use grammar; seriously. That might mean something if I didn't. You know it looks funny when you tell someone to use grammar and you don't capitalize the first letter of your sentence. You mess up at the first letter. I laughed when I read your post; it's meaningless and useless.

 

Why did you take offense at that anyway? It wasn't adressed to you. It was directed at zazzzoom.(I didn't capitalize it because that's not the way he has his name.)

[mustang292]

I do use grammar; seriously. That might mean something if I didn't. You know it looks funny when you tell someone to use grammar and you don't capitalize the first letter of your sentence. You mess up at the first letter. I laughed when I read your post; it's meaningless and useless.

 

Why did you take offense at that anyway? It wasn't adressed to you. It was directed at zazzzoom.(I didn't capitalize it because that's not the way he has his name.)

 

Chill monkey. It was a joke.

[Martin]

but just to get this out there I am a High School Student in my 3rd year. So my being here was suggested by my Chemistry(who is an astronomy buff and he runs astronomy club, which I belong to) teacher, he tells me I've a great scientific mind. I'm here to learn more then debate

 

welcome crazy killer ghost (or ckg for short)

I am glad your chem teacher who runs the astronomy club suggested you

post here, and that you took his suggestion and showed up

 

In my highschool we didnt have an astronomy club. what do your clubmembers do?

 

has anyone in the club ever talked about how astronomers have been able to determine the masses and distances of stars? there is a trick to it which involves (I think, if I am remembering this right) a small cluster of stars called the Hyades. Or maybe i am wrong and you know how the distance scale is really constructed.

 

I put those links for you, to the online redshift-distance calculators (about 5 posts back from here, post #42).

have a look and see if you can get them to calculate a distance

like: suppose some galaxy has redshift z = 2

then how far away is it?

[revprez]

I'd have to say that I believe that the universe is expanding

 

Do you know why?

 

Rev Prez

[zazzzoom]

hay show me your "LOGIC" that space goes on forever and how can it expand if it goes on forever

 

you people act like matter moves somewhere all of a sudden space is created so it can move there that way space is expanding no no no space has to be there for matter to move into

 

SPACE ENDS THAT WAY SPACE HAS A SHAPE

[zazzzoom]

space does not go on forever that way space has a shape