Hubble constant

[Catastrophe]

Thank you. That is very interesting. Looks like we will progress to two curves (or parts) - one 'at the bottom' left) where gravity dominates, and one 'higher up' where the 'straight line' becomes another curve.

Cat

 

[Unclear Engineer]

Cat, here is the link that I did not find last night.
https://hubblesite.org/contents/new... years of meticulous,size in 10 billion years
It contains a lot of other links that provide more info.
But, I don't think it really changes anything with respect to my current understanding of the differing values for expansion rates at different distances (assumed to be different times before present).

 

[Catastrophe]

Unclear Engineer, in your link:
"The measurement is about eight times more precise than Hubble's expected capability. But it's become more than just refining a number to cosmologists. In the interim the mystery of dark energy pushing the universe apart was discovered. To compound things even further, the present expansion rate is different than it is expected to be as the universe appeared shortly after the big bang." Vide #51.

Surely this supports the idea that the expansion is/was not linear? Why should it be?
And why should the line pass through the origin, when we know that at that (imaginary) point the galaxies would be glued together by gravity and the situation very close to t = 0 very uncertain?
I vote for a curve.

Cat

P.S. I also vote for recognition of the fact that the area around the "origin" is governed by gravity and not expansion, and there is no reason on Earth (or beyond) why the line should pass through it. The line should not even be dotted, as has been suggested elsewhere. We just have to accept a discontinuity where gravity takes over (coming backwards/leftwards/downwards. We also have to acknowledge negative velocities, i.e., approaches as in Andromeda Galaxy. And, if the "explosion" causing expansion was so strong, how come nearby galaxies like Andromeda are coming back towards us again?

 

[Unclear Engineer]

I do wonder how people are calculating the "times" that things happened, based on a t=0 assumed to be when all the universe was at a single, dimensionless point.

I think they are looking at red shifts and assuming that those red shifts occurred at a time in the past that they can compute by current apparent distance and the time it takes for light to travel that distance. To me, that is an assumption. And, they can't see anything "earlier" than when the cosmic microwave background radiation was produced, so how exactly do they extrapolate from there back to when the whole universe is theorized to be 10^-x cm in diameter?

What if light we see left its object of origin and traveled through static (not expanding or contracting) space for a while, then encountered a region of space that was expanding during its passage? Wouldn't that violate the assumptions used to estimate the distance to the object and thus the time when the light left the object?

The proponents of the Big Bang Theory seems to want everything to be constant unless it is observed to be otherwise, and even observations get pursued to the nth degree if they violate that assumption. But that assumption its self does not seem to be getting the same level of critical thinking, even though extrapolating everything to infinity or infinitesimal violates the models when it gets close to those limits.

My mind is open to hypotheses that involve not just non-constant expansion with time, but also non-uniform expansion in different regions of space. I am also willing to entertain contractions of space, to go along with expansions.

As I have posted before, the BBT has "solved" its problems of not fitting the observable data by adding so many "fudge" parameters that it now requires us to imagine about 95% of what it takes to fit the data, because we are not detecting what we postulate in that 95%, and only explain it as matter that we cannot detect or explain, accompanied by force that we cannot detect or explain.

Yes, I do believe we should keep looking for dark matter and dark energy. But, even if we find both, I am not convinced that will prove that the whole universe started at a single point. I actually expect that finding those 2 things would point to something other than a singularity, once we actually understand how they work.

 

[Catastrophe]

"
I do wonder how people are calculating the "times" that things happened, based on a t=0 assumed to be when all the universe was at a single, dimensionless point."

This is exactly what II want to know. How can you measure with any certainty 10^-30 when you are talking about a universe? I am thinking seriously about some sort of attenuation. That what they call a tiny fraction of a second might be a thousand years in our money!

Cat

 

[Catastrophe]

"
As I have posted before, the BBT has "solved" its problems of not fitting the observable data by adding so many "fudge" parameters that it now requires us to imagine about 95% of what it takes to fit the data, . . . . . .

. . . . . . I am not convinced that will prove that the whole universe started at a single point. I actually expect that finding those 2 things would point to something other than a singularity, once we actually understand how they work."

I totally agree. The idea of trying to extend a 'fitted' straight line back to a presumed origin does not fit well with me. This 'straight line' has to include a rather sharp inflation.

As many of you will know, I totally reject the t = 0 scenario, including division by zero resulting in this that and the other. I have not rejected a 'nexus' in a cyclic scenario.

Cat

 

[Helio]

"
I do wonder how people are calculating the "times" that things happened, based on a t=0 assumed to be when all the universe was at a single, dimensionless point."

This is exactly what II want to know. How can you measure with any certainty 10^-30 when you are talking about a universe? I am thinking seriously about some sort of attenuation. That what they call a tiny fraction of a second might be a thousand years in our money!

The claims of physics suggesting they have a reasonably secure handle of the conditions just after one Planck second says something incredible about our level of physics, assuming they are correct.

We are limited to direct observations to the time of the CMBR event, but this was 13.8 Gyrs ago, ~ 380k years after day one. But this limitation doesn't stop the physics to extrapolate those 3000K conditions to much high temperatures where a smaller Universe will have a higher temperature that is predictable. Those predictions, now observable, gave us the elemental constraints, for instance, on the ratios of the elements, namely H and He. Almost no other nuclei were allowed to form due mainly to time constraints during the fast expansion (long after Inflation).

Unclear Engr., "As I have posted before, the BBT has "solved" its problems of not fitting the observable data by adding so many "fudge" parameters that it now requires us to imagine about 95% of what it takes to fit the data, because we are not detecting what we postulate in that 95%, and only explain it as matter that we cannot detect or explain, accompanied by force that we cannot detect or explain. "

Given the many, many lines of objective evidence that create a confluence that makes the theory quite strong, as listed in this thread, Big Bang Bullets 2, why do you think so much is imaginary?

 

[Catastrophe]

"why do you think so much is imaginary?"

Are the cooling rates based on in vacuo conditions?

What Earthly cooling rates are they based on?

I cannot believe splits down to 10^-30 et cetera. Such miniscule divisions.
"On what assumptions are these based?"
The map is not the territory.

Cat