Thread: EXPANDING SPEED ?

Hi guys, I'm refering to one of my earlier questions in which the answer infered that the universe expansion rate was speeding up. I've been led to believe recently that the expansion rate was slowing down !

Which is correct, speeding up or slowing down ?

Wouldn't it depend on where in the universe the expansion was measured ? Forgive my naivity but, if there was a clear avenue from the big bang, void of any matter, wouldn't the expansion speed be faster than say, if the avenue was effected by the gravitational pulls of galaxies ? The gravitational pulls acting like the tugging on a bedsheet ?

Forgive me if none of this makes sense, but hopefully sense will come out of it from you guys !

BARCUD

Up until fairly recently, it was assumed that the expansion rate of the Universe was slowing due to the mutual gravitational attraction of its components. What wasn't known was the rate of that slowing. If it was too small, then the Universe would continue to expand forever (the expansion would continue to slow, but never quite stop). If it was large enough, then eventually the expansion would stop and the Universe would collapse into a "Big Crunch".

In 1998, some research was done to determine which was the case. It worked like this:

Type Ia supernovae can be used as a standard light measurement. By measuring how bright they appear you can tell how far away they are. You can then use the Doppler shift to determine how fast they are receding. Thus by measuring the relative brightness of these super novae in distant galaxies and the relative redshift of these galaxies you can plot distance versus recession speed.

Since the speed of light is finite and fixed, the light we receive from distant galaxies is light that left a long time ago, the further the galaxy the further back in time we are looking. So we are also plotting recession speed against time. IOW, it gives a map of how the Universe has expanded over time.

The surprising result was that the Universe, instead of slowing its expansion rate over time, Had been increasing its rate of expansion.

Since then this finding of an accelerating Universe has been independently confirmed by other observations.

It is an example in science where we went looking for one thing and found something completely different.

Ah there you are !? It took me a little while to find where my post had gone from the 'Physics' forum.

A nice and straight forward answer I can understand Janus, thanks very much

An increasingly expanding universe ! So the scenario of the universe reversing back to the site of the big bang isn't going to happen just yet ! Singularity ? Or the universe isn't going to act as if it is on an elastic band and 'boing' back and forth ?

So I assume then Janus that we actually know which direction the universe is travelling in ? Is it in fact travelling in a straight line as on a rail line OR is it travelling outwards as from an explosion ?

many thanks again,

BARCUD

Originally Posted by BARCUD

Hi guys, I'm refering to one of my earlier questions in which the answer infered that the universe expansion rate was speeding up. I've been led to believe recently that the expansion rate was slowing down !

Which is correct, speeding up or slowing down ?

Wouldn't it depend on where in the universe the expansion was measured ? Forgive my naivity but, if there was a clear avenue from the big bang, void of any matter, wouldn't the expansion speed be faster than say, if the avenue was effected by the gravitational pulls of galaxies ? The gravitational pulls acting like the tugging on a bedsheet ?

Forgive me if none of this makes sense, but hopefully sense will come out of it from you guys !

BARCUD

See my new article 'Mathematical Proof' that IMO, falsifies the BBT.
So there is no expansion of space.
My opinion is that we have a Flat Space universe where there is no expansion or contraction.

Cosmo

Type 1A supernovae were thought to be standard candles till one was found twicve as bright as normal because it had more mass than normal, simply because it was rotating faster so didn't collapse into a supernovae so quickly. Therre are other mechanisms that can cause different kinds of Type 1A explosions, so not really accurate after all.

The cosmological redshift is a measure of distance travelled but not because a vacuum can expand as cranks claim but because gravity redshifts photons which travel through it and the universe is full of gravitational sources, so photons redshift over cosmic distances.

Erm . . . I'm a little confused now ! The universe is expanding and accelerating as it does so, yes ? I certainly couldn't understand any mathematical theories so I'm not sure what is being said there !?

BARCUD

I've just joined this forum so forgive me if this topic has been exhausted.

How accurate are the measurements used to determine an expanding universe when all matter (and space & time) are also expanding? Surely this would skew the results one way or another. If so, then how can we be sure that expansion is actually happening?

Secondly, could not the perceived expansion actually be a contraction? Just because things seem to be moving away from the observer it doesn't mean that things are expanding. The same observatin could be made in a contracting universe where the observer is contracting faster and objects far away and long ago are contracting slower.

Thanks

The big bang idea requires that we have a singularity which inflates then expands. Singularities are ultimately stable. They have densities that make a standard black hole look like atmospheric pressure. Matter is created and despite such densities, the universe ignores gravity and continues expanding.

The balloon idea is used for how it works but it needs a four physical dimension hypersphere to work since it cannot work in three dimensions. Proof of a fourth dimension is....missing. Proof that hyperspheres can exist is....missing.

Several billion years ago according to BB dogma, the universe started expanding faster. Before that time, anti-gravity was said to be impossible. Suddenly we have the invention of dark energy, which is anti-gravity energy. It makes up 3/4 of the universe and there is not a shred of evidence that it exists.

As you can see, the big bang idea is one step short of creationism.

the BBT is one step short of creationism only in the minds of the stubborn really, the universe is expanding outwards, however you want to look at it, things are moving away from us, we can show this by redshift which has been proven to wrk on a smaller scale on earth, we know things are moving in a rough outward expansion, so the volume of space the universal matter occupies is increasing even if the universe technically is not
the expansion of the volume containing the matter proves there must be a start point if everything is going in a direction then sometime ago it will have been going slightly faster in a slightly different spot, if you follow this basis back far enough you end up with a point where all the matter starts at roughly the same point computer simulations have and can show this
the BBT is a theory but it is a theory about something which must have happened, same way the dinosaur killing comet is only a theory but we know something killed the dinosaurs and there is evidence for a collosal comet impact at roughly the same time,
the only way you can claim no BBT in any form has never happened is if you argue the theoretical thinking that if time and space were created moments after the BB then the BB can never have happened because there is no time during or before the BB so anything at that moment is infinite

The universe APPEARS to be expanding, the truth is we have NO external reference and therefore cannot be certain. Yep I know you are all going to shout but that is the way it is, we have NO external reference.

This is a great forum but unfortunately on reading more posts more questions are provoked! So in that vein, a quick one about the speed of the expansion of the universe and, subsequently, its age.

If the universe (space) is expanding, is time also expanding? The Big Bang Theory says that all matter, space and time were created at once. If time IS expanding then is the age of it as measured in earth years wrong? Did time pass quicker long ago and gradually be slowing down? If time is slowing down and space (distance) is increasing then how does this affect D=S/T if S is constant (speed of light)?

Thanks

I don't think matter is expanding. I think the forces that hold matter together, and probably solar systems and galaxies are stronger than expanding space.

So I think that galaxies are accelerating away from us in the outer reaches of the universe at speeds that may exceed light speed. However, I don't think this means that galaxies are getting "bigger".

I don't know if there is any evidence that space is getting more dilute as the universe expands. It may be impossible to measure this. I suppose that it could be diluting, or not, depending on whether more space is coming in from someplace we cannot see--such as another dimension??

Sorry but my previous post was wrong. I meant to say S=D/T.

Ta[/quote]

Booms. Gravity produces a redshift indistinguishable from recessional velocity. The universe is full of gravitational sources. Gravity is homogeneous over great distances.

What a neutron star can do within miles and inside a galaxy can do within hundreds of light years, the universe does within millions/billions of light years. A photon travelling billions of light years is subject to a non-directional continuous drag from every gravitational source in the universe, like it was travelling through a sea of gravity. The red shift is a measure of distance and not a mythical expansion which relies on so many impossibilities.

The BB idea relies on a four physical dimensional hypersphere. If the universe started off with a standard three dimensional expansion, then we would have a point of origin from where everything started.

A computer simulation can only work if you ignore gravity. Heard of black holes? Imagine one with such incredible density that it makes the standard black hole look like normal atmospheric pressure. Black holes don't expand so why would something trillions of times more dense expand? Making out it is some magical form of singularity is dishonest.

Infinite is a mathematical term. The BB idea does not explain how the imaginary singularity appeared or how it disobeyed gravity, how it expanded in four dimensions instead of three, etc. Anti gravity is said to be impossible. Dark energy is anti gravity energy. 3/4 of the universe is said to be made of dark energy. Evidence for dark energy is non-existent because it is imaginary.

Paul D. Spacetime is a nonsensical description. It was thought up by mathematicians like Hawkings who sometimes blur their work with the real world. It is space. We do not need a Dr Who style Tardis to get to the Moon. A standard rocket does the job since it merely travels through space.

Time is a man-made measure of change. It does not really exist except when working out calculations since we forever live in NOW.