What is Mainstream views on...

[Farsight]

Forgetting the pedant...

It's important to get this stuff right. There's a lot of popscience misinformation out there.

 

[hansda]

Space isn't curved in a a gravitational field.

We know that space is expanding because universe is expanding. That means space has some elasticity, which can be stretched. So, if space can be stretched, it can also bend or curve.

Instead it's inhomogeneous.

What do you mean by inhomogeneous? Its density is changing?

Light curves in a similar fashion to the way sound waves curve underwater, see this sonar article:

The water isn't curved, instead it's inhomogeneous. The temperature and/or salinity and/or density varies with depth, and so does the speed of sound.

So you mean light bends due refraction(due density change)?

 

[hansda]

In Newtonian model of gravity, is there any concept of curvature?

Not really. But Newton did say this in Opticks query 20:

"Doth not this aethereal medium in passing out of water, glass, crystal, and other compact and dense bodies in empty spaces, grow denser and denser by degrees, and by that means refract the rays of light not in a point, but by bending them gradually in curve lines?"

I think this is fairly close to what Einstein said about space being neither homogeneous nor isotropic.

Read your quote of Newton. Here Newton considered bending of light as an effect of refraction rather than an effect of gravity.

 

[paddoboy]

It's important to get this stuff right. There's a lot of popscience misinformation out there.

Certainly is important to get things right and mostly they do in time.

 

[The God]

The named user has put you, according to recent posts, deservedly on ignore. In every case, you would have been better served writing a simple essay stating in positive terms what you believe and why you believe it rather than trying to tear down the position of another which you may not be fully equipped to understand.[/COLOR]]

Why are you adjudicating on his putting me on ignore or not ? You are placing yourself where you are not required.

I had requested Mods to clear the air, even Schneibster urged Rpenner to put forth his views on one of the points, but he is yet to make any comments.

[Moderator: You don't have the right to demand an answer.]

asking Mods to clear the air, does not fall in right or no right to demand an answer ? Its sad that you took action without understanding the intent of the post properly.

Moderator: Observationally, cosmological redshift is indistinguishable from Doppler shift or gravitational redshift.

So ? the same effect does not make the causal processes same.
I had very clearly stated that from the resultant redshift, doppler shift due to peculiar velocities cannot be separated out easily.

2. Spacetime is a thing (in Physical sense), otherwise how will it have curvature etc. [Moderator: What is treated like a real thing in physics is the geometry and curvature of space-time just like the electromagnetic field was treated like a real thing in Maxwellian electrodynamics. But relativity shows what was important in old EM theory was not the description of the E field and M field in any one set of coordinates but the geometric description of the EM field in general coordinates. So provisionally (until a better theory of space, time and electromagnetism comes along) the geometry of space-time is treated like a real thing. Colloquially, this means space-time is real thing. Arguing about if that's true is specious, unimportant and the promotion of form over substance. Creating a new thread to argue about that without citing the original claim in context is a breach of civility and best practices.]

Irrelevant lecture......I cited Prof Geraint f Lewis paper and his statement that spacetime is not a thing, it is a mathematical tool. And your last line shows, you did not see the thread, where this issue was taken up and your attention was drawn. You should have asked me where the original claim was made, I have hinted that I asked you for clarification, you took hasty and improper action.

3. Big Bang happened after Inflation. [Moderator: Big Bang cosmology is the observation that the earlier universe was hotter and denser and more uniform without empirical limits. All times when the universe was too hot and uniform to allow stars to form are part of Big Bang cosmology, because such conditions were terribly at odds with the old competitor called Steady State. Inflation is a mechanism proposed to allow the early universe to be super-uniform. To rigorously address any hypothetical first event in Big Bang cosmology one needs a theory of physics which correctly describes such events, which has never been part of the conversation. But many aspects of Big Bang cosmology must have happened long after the period when any hypothetical inflation mechanism was important and therefore after the hypothetical first event. Therefore this sentence makes no sense bereft of original context. Inflation, if it happened, was important during part of the Big Bang early universe. So creating a new thread to argue about it as if it was another's simple claim is a disservice to the forum community and betrays either a misunderstanding of cosmology or a willingness to write nonsense.]

Again hasty and incorrect response....you should have asked me that where Schneibster has claimed that BB came after inflation ? He has categorically stated that, few members objected to that. You are the only person seeking original reference.

Shocking, Rpenner, that you have not categorically responded on these three points. As a member you have right to remain silent, but not as Moderator. I am on this board, from day one I am of the opinion that nothing incorrect should remain on board, wherever possible. You are letting 2-3 crucial mainstream points hanging in air for want of taking on your invited pal schneibster.

 

[Xelasnave.1947]

TG please think about airing your complaints here.

It is wrong in so many ways.

You seem to have ignored all that has been said in the other thread.

Your concerns have been dealt with but if you have issues take the trouble to do a PM to the moderator.

You are digging a hole which looks more like a grave each time you post.

I can not imagine you not being banned in most other forums.

I beg you give it a rest for your sake.

I do not know what else to say to you.

Alex

 

[paddoboy]

So ? the same effect does not make the causal processes same.
I had very clearly stated that from the resultant redshift, doppler shift due to peculiar velocities cannot be separated out easily.

Well what are you claiming? The effects of doppler and cosmological redshift are observationally indistinguishable. But cosmological redshift is only viewed with distant galaxies: Doppler is a much smaller effect, due to peculiar velocities.Cosmological experience and known data, are tools cosmologists use to weed one out from the other.
So are you now claiming that there is for some unknown reason, some sort of fraudulent behaviour going on with mainstream that you have already claimed happened with GP-B and LIGO, solely to support an expanding universe?
I mean at this stage, I do not know where you are coming from, nor where you are going to.
This may help in deciphering what I'm trying to tell you....
https://einstein.stanford.edu/content/relativity/a11859.html
Cosmological redshifts are only seen unambiguously at distances of 100s of megaparsecs. At nearer distances, ordinary Doppler shifts from galaxian motion with respect to a local center of mass ( galaxy cluster) is comparable to the cosmological effect and you have to disentangle the two contributions very carefully. Typical galaxy speeds in a cluster are 300 km/sec, and this equals the cosmological recession at a distance of only 5 megaparsecs or so!
more at link.

Irrelevant lecture......I cited Prof Geraint f Lewis paper and his statement that spacetime is not a thing, it is a mathematical tool. And your last line shows, you did not see the thread, where this issue was taken up and your attention was drawn. You should have asked me where the original claim was made, I have hinted that I asked you for clarification, you took hasty and improper action.

Yet it is rare for you to take notice of any mainstream opinion and/or link: We have had many professional replies and you deride most.
The reality or otherwise of spacetime is simply a semantical argument based on what an individual sees as the meaning of "real". Some see time as real, others do not.
I have the utmost respect for Professor Lewis and have personally met him.
In this instant, I'm sure he could enlighten you further if he were a part of this forum and could see where you are trying to take this.
Plus I have given link supporting my stance that spacetime is real.
https://www.quora.com/Is-spacetime-a-real-thing-or-just-a-mere-concept
https://einstein.stanford.edu/content/relativity/q411.html

Again hasty and incorrect response....you should have asked me that where Schneibster has claimed that BB came after inflation ? He has categorically stated that, few members objected to that. You are the only person seeking original reference.

I raised that with Schneibs and suggested "Eternal Inflation" an aspect brucep was keen on.

I am of the opinion that nothing incorrect should remain on board, wherever possible. You are letting 2-3 crucial mainstream points hanging in air for want of taking on your invited pal schneibster.

I agree with regard to incorrect info.
But there are some aspects of cosmology, [as in the stretching of light and frames of references] and light bending or saying spacetime is simply curved with light following geodesics that are simply varying interpretations and neither are wrong.
And who is to decide what is wrong and what is right...you?
You seem to be suggesting somewhat with your statement "for want of taking on your invited pal schneibster" that he is a plant.
You seem to want to stoop to many suggestions when people are refuting your take on cosmology.
You have also derided me for "liking" Schneibs.
Please, with all due respect, take a step back, and ask yourself honestly where you are coming from.
I see nothing wrong in questioning certain aspects of cosmology......I have done it and continue to do it as I have today with Schneibs.
But when a poster continues to posts threads that just happen to question every aspect of mainstream accepted cosmology that he is able to think of, then alarm bells start ringing.

 

[Bells]

Mod Note

Thread closed since this is not the place for this thread, not to mention this thread is not exactly appropriate and this issue is being discussed here and elsewhere.