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RECENT POSTS IN THIS TOPIC

Jonathan Dickau: on 5/20/20 at 13:20pm UTC, wrote Thank you Peter... For the kind words of explanation. It is looking like...

Zeeya Merali: on 5/20/20 at 10:40am UTC, wrote Hi Jonathan, Well, I am sure Niayesh Afshordi will be pleased to see that...

Peter Jackson: on 5/20/20 at 9:47am UTC, wrote Jonathan, 'Dark Flow', it's axis and helicity are what WMAP...

Jonathan Dickau: on 5/19/20 at 16:45pm UTC, wrote Well now that's a lot of egg on my face... This is 12 year old news. ...

Jonathan Dickau: on 5/19/20 at 14:33pm UTC, wrote As it turns out... The appearance of a dark flow, as described by...

Jonathan Dickau: on 5/19/20 at 11:24am UTC, wrote Greetings Professor Afshordi, In your work with Pourhasan and Mann a few...

Plato: on 10/3/08 at 12:16pm UTC, wrote Oops Picture one should be two, and vice versa.

Plato: on 10/3/08 at 12:14pm UTC, wrote One would have to understand the full scope of the geometrical propensity...


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FQXi BLOGS
December 2, 2020

CATEGORY: Blog [back]
TOPIC: From Cosmic Lighthouses to Dark Flow, by Niayesh Afshordi [refresh]
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FQXi Administrator Zeeya Merali wrote on Sep. 30, 2008 @ 19:33 GMT
Everybody’s been talking about the new and mysterious “dark flow” that’s supposedly tugging on galaxies from beyond the edge of the observable universe. Cosmologist Niayesh Afshordi wonders if it really deserves the hype.

From Niayesh Afshordi:

It is no secret that modern cosmologists have developed an obsession with the dark sciences; or at least, that’s what you may think...

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v wrote on Oct. 1, 2008 @ 13:13 GMT
Niayesh,

Not being a physicist, could you explain in simple terms what the "beta model" is? what other models are there? and which model do you think might have been more representative? how dramatically would the use of a particular model affect the results?

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Niayesh wrote on Oct. 1, 2008 @ 20:41 GMT
In the beta model, the gas density is assumed to be spherically symmetric and falling off as (1+(r/r_c)^2)^(-1.5*beta), where r is the distance from the cluster center and r_c and beta are constants. The gas temperature is also assumed to be constant. There is no physical reason for any of these assumptions and some of them may be very badly broken. In particular, if you use X-ray data to fit for the best beta-model, it tends to underpredict the gas density on small scales and overpredict it on large scales. The latter could be particularly problematic for interpreting Sunyaev-Zeldovich observations.

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Plato wrote on Oct. 3, 2008 @ 12:14 GMT
One would have to understand the full scope of the geometrical propensity of that event. Whether one might call it the "spherical cow" or not, it follows that this effect blinds, while considered quite a natural function in our everyday world. The light has often caught most of us off guard.

Of course thanks to one of the blog post contributors here should be mentioned to help in this understanding. As well that one would like to help explain PI's understanding and idea of the "mathematical construct" presented by Tegmark

It would be of some help if some more html choices to italicizing quotes might be allowed here and links.

First picture

"We see a pulsar, then, when one of its beams of radiation crosses our line-of-sight. In this way, a pulsar is like a lighthouse. The light from a lighthouse appears to be "pulsing" because it only crosses our line-of-sight once each time it spins. Similarly, a pulsar "pulses" because we see bright flashes every time the star spins."

Second Picture

"When scientists refer to a spherical cow, we are poking fun at ourselves. We are admitting that some of our models or descriptions of things are far more simple than the actual object, like to say that a cow has a spherical shape. The phenomena we study are often complex, and including too many details can hinder, rather than help our understanding. Often it is useful to study a simplified model which contains only the most important general characteristics. Such a model can be more easily studied using numerical or analytical methods and then compared to observations."

It would help to read a bit on spherical cow to get the jest of the understanding what an event can reveal in the Lighthouse.

"Generally the SNR looks different "in each of these different wavelengths", just like you and I look different to another human being (who looks at the visible light) then we do to a bee or a snake (who are able to detect ultraviolet and infrared light, respectively)."

Our measures(In gamma) help us to see in other ways. Consider high energy particle release? Glast. Calorimetric information.

Best,

attachments: lighthouse_pulsar.gif, SNRcartoon_small.gif

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Plato wrote on Oct. 3, 2008 @ 12:16 GMT
Oops

Picture one should be two, and vice versa.

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Jonathan J. Dickau wrote on May. 19, 2020 @ 11:24 GMT
Greetings Professor Afshordi,

In your work with Pourhasan and Mann a few years back; you proposed a scenario where a black hole in a 5-d universe created a white hole in 4-d spacetime, whose emanations shoud appear to come from everywhere like the CMB. My research predicts a similar transition for the early universe, and suggests it may be part of an even larger trend.

At the ultra mega large scale; the cosmos would be asymmetric (a global asymmetry), even while local symmetries hold to millions of light years out, and this means we are headed toward another black hole at the cold dark end of our universe. If this is true; could we be feeling the pull of that black hole already? Could distant clusters be feeling its effect?

All the Best,

Jonathan

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Jonathan J. Dickau wrote on May. 19, 2020 @ 14:33 GMT
As it turns out...

The appearance of a dark flow, as described by Professor Afshordi, is predicted by my research (or at least this is confirmatory). And these results were presented at a breakout session on Quantum and Analog Gravity Models at GR22 in Valencia last year, hosted by him. So he is somewhat familiar with my work.

I was very fortunate to have my posters presented even though I was forced to be absent due to my father's illness and hospitalization. I have to thank Jorge Pullin, Ivan Agullo, and Niayesh Afshordi for assisting to make that possible. My Dad had several months of relative health and well-being before getting hit with Covid-19 and perishing a day before his 88th birthday.

But at this time; I want to share the same material more broadly, and to encourage discussion, as it appears to directly relate to this forum article.

My poster is downloadable here:

Theories of Quantum and Analog Gravity Represented in the Mandelbrot Set (Poster)

The published paper is available here:

Theories of Quantum & Analog Gravity Represented in the Mandelbrot Set

And my submission for the Gravity Research Foundation 2020 awards, a very brief paper summarizing this work, is attached.

Warm Regards,

Jonathan

attachments: Confluence.pdf

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Jonathan J. Dickau wrote on May. 19, 2020 @ 16:45 GMT
Well now that's a lot of egg on my face...

This is 12 year old news. Probably long disproved. The fact it appeared on the front page was triggered by someone posting spam. I even marked their comment for deletion, but I never checked the date of the article. Boy oh boy....

Regards,

Jonathan

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Peter Jackson wrote on May. 20, 2020 @ 09:47 GMT
Jonathan,

'Dark Flow', it's axis and helicity are what WMAP and Planck have confirmed in increasing detail, proving the inconsistency of our (Big Bang/Black Hole) cosmological model which can't produce them. As officially announced (if ignored!). Was it the flow you referred to? They're the main elements of the set termed the CMB's 'peculiar anisotropies' which I referred to in my essay. Only ONE alternative model has so far reproduced them, the cyclic one I also referred to.

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FQXi Administrator Zeeya Merali wrote on May. 20, 2020 @ 10:40 GMT
Hi Jonathan,

Well, I am sure Niayesh Afshordi will be pleased to see that his work is still being discussed. :) Sorry, it looks like we're having a bit of difficulty with spam resurrecting old posts. We're trying to fix things now.

FWIW (according to Wikipedia at least!), Planck found no evidence for Dark Flow (https://arxiv.org/abs/1303.5090), back in 2013, but another team claimed to see some evidence in WMAP and Planck data in 2014: https://arxiv.org/abs/1411.4180. Make of that what you will...

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Jonathan J. Dickau wrote on May. 20, 2020 @ 13:20 GMT
Thank you Peter...

For the kind words of explanation. It is looking like my research predicts a bounce at the end of this major cycle, and that the current state of the universe is the rebound from an earlier bounce. So there is some agreement.

Thank you Zeeya...

Your thoughtful explanation makes me feel like less of a nitwit. And I'll be more well-informed on the current state of this debate from now on. I just have to look at the date of the initial post next time something pops up.

All the Best,

Jonathan

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