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  #1  
Old 11-04-2017, 09:08 AM
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Dark energy... illusion or not?

Interesting read:
http://www.sciencemag.org/news/2017/...illusion-12136

Last edited by bojan; 11-04-2017 at 09:09 AM. Reason: more info
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  #2  
Old 12-04-2017, 11:13 AM
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Fascinating! It would be nice to be able to explain away dark energy in terms of inhomogeneities within the universe and known physics.

I wonder to what scale we really have to go to assume the universe is homogeneous. With known galactic filaments and huge structures such as the Sloan Great Wall, our observable universe isn't all that homogeneous.

Thanks for the post, Rob
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  #3  
Old 13-04-2017, 08:16 AM
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Hm, I fundamentally agree dark energy doesnt exist but for differing reasons. This acceleration of the universe has never sat well with me with how its "proven" with recent observations of ever older galaxies, which to me they are just seeing back in the past when accelaration from the "big bang event" would have been greater than now as I'd expect.

A lot of all this relies on measurements and constants that I feel are not accurate enough yet either, just too much guesswork going on it seems. Admitedly my maths isnt up to the task of even attempting to understand, let alone work through any of these papers.

I have encountered the assumption that figure rounding has no bearing on a simulation, it still gets you in the ballpark. In a venus transit project I contributed data on I was able to show that the simulation software was rounding a value from two to one decimal places and instead of projecting a straight path for venus across the sun it was an obvious banana curve which was clearly wrong and using actual observation data showed the rounding had to be present in their equation values even though it shouldn't have had any appreciable difference.

So I expect someone will take the time to review from scratch how to calculate the expansion rate accurately, then take precise data from observations to as good a precision as possible, and likewise to constants (which arent) and run the equations with full values until the very final result. Is there even s single source of truth data set in existance? I know things like the number of stars in a galaxy is an ever shifting estimate so if someone needs that value for a paper what would they use? We need a dataset that people can work through and add to that produces a final "cuurently accurate as of today" value instead of different groups having to redo the entire estimate in isolation every time.
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  #4  
Old 13-04-2017, 03:43 PM
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Quote:
Originally Posted by sil View Post
Hm, I fundamentally agree dark energy doesnt exist but for differing reasons. This acceleration of the universe has never sat well with me with how its "proven" with recent observations of ever older galaxies, which to me they are just seeing back in the past when accelaration from the "big bang event" would have been greater than now as I'd expect.
I tend to lean this way. I like it because it is simple and has more common sense than the introduction of an imaginary friend. Having a simple function of c and G as a function of t seems an elegant solution.


Recent article -> https://www.theguardian.com/science/...soon-be-tested
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  #5  
Old 13-04-2017, 10:45 PM
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Seen this yet?
Quote:
Researchers at the University of Waterloo have been able to capture the first composite image of a dark matter bridge that connects galaxies together. The scientists publish their work in a new paper in Monthly Notices of the Royal Astronomical Society.
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  #6  
Old 14-04-2017, 02:15 PM
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We can only go with any postulate on real evidence.

Telescopes are being planned to survey thousands of type 1A supernovae to pin down an expansion curve for our Universe.

The real problem is if you calculate the so called Dark Energy from Quantum Mechanics you end up being out by a factor of 10 to the power of 120!

This is the biggest error in the history of Physics. There has only been 10 to 27 seconds since the big bang.

There will be wild postulations to do with Dark Energy and Dark Matter. Most from uninformed sources.

All that matters is data from measurements or just more experiments.

Dark Energy and Dark Matter in Our Universe seems to be at just the correct level for all of us to even exist.

To me this is self evident! We are here because we are here!

Bert
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  #7  
Old 08-06-2017, 08:46 AM
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Here is a very good talk by Sean Carroll on Dark Matter and or modifying Einstein's General Relativity.

https://www.youtube.com/watch?v=4uogQiH5Yx4

This is a very good talk as well on Quantum Field Theory.

https://www.youtube.com/watch?v=gEKSpZPByD0

The Universe consists of Quantum Fields rather than particles.

Bert
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  #8  
Old 10-06-2017, 07:09 AM
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This post reports on a recent paper that offers some verification of the emergent gravity hypothesis.

https://darkmatterdarkenergy.com/201...ndes-proposal/

Margaret Brouwer's check of galaxies is not the final word in the saga, but it does provide some evidence that the dark matter solution to galactic rotation velocity curves might not be the right answer.

Regards,
Tony Barry
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  #9  
Old 19-06-2017, 01:48 PM
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Quote:
Originally Posted by tonybarry View Post
This post reports on a recent paper that offers some verification of the emergent gravity hypothesis.

https://darkmatterdarkenergy.com/201...ndes-proposal/

Margaret Brouwer's check of galaxies is not the final word in the saga, but it does provide some evidence that the dark matter solution to galactic rotation velocity curves might not be the right answer.

Regards,
Tony Barry
WSAAG
Arxiv paper is here.

However... there are other opinions:
https://www.technologyreview.com/s/4...nt-phenomenon/
http://physicsfromtheedge.blogspot.c...gravity-1.html

Last edited by bojan; 19-06-2017 at 02:11 PM.
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  #10  
Old 19-06-2017, 08:17 PM
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Thank you Bojan for the links. I read Mike McCulloch's brief posts and was intrigued. As he says,

Quote:
The variant of inertial-MoND was an inspiration to me, but MoND and MiHsC differ in their predictions and also in that MoND is only an empirical 'fit': it has to be fitted to the data by hand with a constant a0, and there is no physical reason given for it, whereas MiHsC is based on logic, has a good physical reason and predicts well without any arbitrary fitting. This is a profound advantage.
It's a good time to be alive, these problems are being looked at harder and harder than ever before. Something's gotta give.

Regards,
Tony Barry
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  #11  
Old 04-07-2017, 03:33 PM
sil
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Originally Posted by tonybarry View Post
It's a good time to be alive, these problems are being looked at harder and harder than ever before. Something's gotta give.

... but maybe not provably in our lifetimes. Some observation I read about dont take into account their observed events in time only in distance, which to me takes me to different conclusions than they come to. I think we're in a transition period and some people need to relax and be patient (ie media) for results to be examined and peer reviewed before making press announcements and hyped promises on the return/meaning. I dont think we yet have the precision in many tools to make the correct measurements. Instead we are building tools that can find "something" then the next project comes along with an alternate tool/method and finds the same something. They can then start to calibrate and refine off each other to get a tool that can take confident measurements with certainty about what the "something" actually is. Then another project will see how to build on that to find/measure another something. All the way the tools are refining so are the theoretical models to build the full picture to explain it all. Its a little uncomfortable our current best model is one that is aesthetically pleasing and we are working to explore the gaps that have yet to be observed, we haven't yet got all the pieces of the jigsaw, just the picture on the box and hunting for the pieces to fit. Somewhat sloppy I guess but the bottom line we are making observations and collecting data which is key. Eventually we'll have an understanding that allows us to look back on our old data and understand the hidden signal better. We've seen it already after LIGO published, people were able to use that to examine their old data and recognise the signal that was there all along.

Good to see progress in science at least even if the Australian Government isnt too keen on fostering it. Will we survive as a species though to understand enough science for technology to save us.
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  #12  
Old 09-08-2017, 10:32 PM
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Is the evidence for dark energy flimsy?

Many seem to think so, but one notes the absence of any supporting in-depth studies to back up the doubts.

If one is to doubt dark energy, the science support has to be at least on the level of this presentation, which is the state of our knowledge on the matter today.

=Dana in S Africa
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  #13  
Old 10-08-2017, 06:12 PM
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Gravity does not Suck

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Not that my opinion counts for zip but I believe they are going down the wrong street.
GR rules and its hard to throw but observations are bent to fit in my view.
We are convinced the universe is expanding but is it really? Personally I think steady state makes more sence but I have no qualification so my view is only crack pot and I have no problem with being crack pot but I await a better model than GR even if that is worse than saying I don't believe in God.
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  #14  
Old Today, 09:48 AM
sil
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Quote:
Originally Posted by luka View Post
image of a dark matter
Contradiction in terms. Its a worrying trend that there is a lot of pictures of new things being released to "prove" something new and exotic just because they can make a plausible story to explain or they ignore the papers before hand. Just like the value of the Higg's "absolutely HAD to be only one of two energy values to prove it exists, but the lhc found something at a third value instead not the two precise ones it had to be and still declared it the higgs anyway.
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  #15  
Old Today, 09:54 AM
sil
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Originally Posted by xelasnave View Post
Not that my opinion counts for zip but I believe they are going down the wrong street.
GR rules and its hard to throw but observations are bent to fit in my view.
We are convinced the universe is expanding but is it really? Personally I think steady state makes more sence but I have no qualification so my view is only crack pot and I have no problem with being crack pot but I await a better model than GR even if that is worse than saying I don't believe in God.
I'm radical and think its neither, that it is slowing down as it should. But I also have an idea how it could expand faster (though I believe thats a misinterpretation of the observations). Maybe one day I'll have my skills up to scratch to try exploring the data and equations for myself which I'm not qualified to do. On the other hand I also have a good case for time travel being possible into the past and how the existence of the bible itself is proof it has happened. and people wonder why scientists are presented as crackpots in movies.
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  #16  
Old Today, 10:22 AM
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Gravity does not Suck

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I have no skill and less education but I know I am right

That's a good start to be a crack pot.

It is unfortunate how scientists are represented in my view they don't deserve such.

Although TV shows like CSI have done wonders for presenting a better image.

Alex
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