Dark energy: Einstein may have been right (again)

Reading the entire article indicates that the expansion of the universe is accelerating. Does anyone in this group know the change in the Hubble constant, if any, since Hubble defined it? Its likely to be very small.

BernieK

Hi berniek, you asked: "Does anyone in this group know the change in the Hubble constant..."

The Hubble constant has a very "non-constant" history. Hubble originally determined it to be Ho = 50+-15 km/s/Mpc, based on a 'distance ladder' that was not very accurate (distances very consistently overstated). The cosmological redshifts can be measured very accurately, but without accurate distance, the value of Ho is inaccurate.

Later observational techniques with Cepheid variable stars and supernovae steadily improved the 'distance ladder' and the value of Ho has been revised upwards, until today, where Ho is taken to be around 72 km/s/Mpc (I'm not sure of the error band, probably +- 5 units).

This has however nothing to do with the presumed accelerating expansion of the universe, because on a human timescale, Ho cannot change measurably, as you suspected. On cosmological timescales, Ho must have been much higher in the distant past and it will become higher again in the far future, due to the accelerating expansion that apparently only started "recently", at about the time of our solar system's formation.

Jorrie

Albert Einstein................................................

'What a guy!'

(Copyright Red Dwarf)

You actually mean Ace Rimmer!

Too funny!

Smoke that man a kipper!

Dear Jorrie

The dark energy is vacuum and space is filled with non-interactive matter was realized long ago. People now only repeating what others have written in their books many years ago. Idea of anything pushing anything else is also very subjective. There may be a slow standing wave formation in the universe, which one may observe in one way now and other way some time later on very long time scale. Perhaps the communication is very slow and we are observing one phase of it now. If this phase is to be seen correctly in time then it also requires information arrival time correction. One needs to reconstruct the entire information for any given time and then look at that. Looking into different times slots from different places and calling it of one time information is very much wrong projection of raw data. There are only few who project such data and others find it only amusing.

Jorrie I'm the old guy that is fascinated by cosmology like you. I think of galaxies as islands in a giant "vacuum" ocean. I believe we have the gravity model correct that exists inside galaxies. But the gravity model is probably different between galaxies in the outer universal vacuum.

Inside the galaxies there's still plenty of phenomenon for which we need answers. A big one is the black hole. If the expansion of space was caused by the big bang and the inflation energy from the annilhation of anti-matter, then as the baryons and dark matter get dispersed further apart by the outward thrust you can see how a hockey stick expansion may come somewhere down the road. It could even cause the space vacuum to be ripped into pieces.

Everything in what we call "the universe" is increasing in size because of this expansion right down to the smallest particle. Eventually a single atom may cover the space now used by the solar system. Is the universe a rubber mattress pad or a Roman candle?

All very fascinating!

Hi Guest, you wrote: "Everything in what we call "the universe" is increasing in size because of this expansion right down to the smallest particle. Eventually a single atom may cover the space now used by the solar system"

I sincerely hope that you are not a supporter of that crackpot idea "expansion theory", as portrayed in a book of which the ad says: "the book scientists hope you never read"... It may be an entertaining read, but it is not science!

Regards, Jorrie

Why are publishers convinced that people want to read something with the tag 'the book scientist's hope you never read.' I want to read the book that says 'the book politicians hope you never read.' I think that would be more informative.

My modest opinion is that light, since the instant when it is emitted at some initial wavelength, it starts increasing its wavelength in a fixed percent in function of the radius of the spherical wave front, and that while that radius remains below some million light years the wavelength percent increase is negligible in comparison to the initial wavelength, but on escalation above some thousand million light years, the percent increment begins to be noticeable in comparison to the initial wavelength, something like the following:

Relative Radius __Relative Wavelength

1 _____________1.000000000001

10 ____________1.00000000001

100 ___________1.0000000001

1000 __________1.000000001

10000 _________1.00000001

100000 ________1.0000001

1000000 _______1.000001

10000000 ______1.00001

100000000 _____1.0001

1000000000 ____1.001

10000000000 ___1.01

I believe this because if universe were expanding since the "big-bang", then the "attack front" should have reached the speed of light long ago, thus universe frontier should be in the infinite.

Jaime Soto Figueroa

http://www.matharts.cl/

If the universe keeps expanding at an accelerated rate we will eventually find "stretch marks" in it's fabric. Mr. Jenius

All those use bullet in a barrel model for acceleration for expanding universe, use wrong parameters in time, which gives different meaning to the same thing in one time location. The shift can come from spin itself. Galaxies away were spinning at different rate than those are at near point in different time. They are not moving away into anywhere. Spin under structure formations changes due to material movement under gravity and in new formed structures it acquires another status.