APOD: Gravity's Grin (2017 Aug 05)

Comments and questions about the APOD on the main view screen.
User avatar
APOD Robot
Otto Posterman
Posts: 2908
Joined: Fri Dec 04, 2009 3:27 am

APOD: Gravity's Grin (2017 Aug 05)

Postby APOD Robot » Sat Aug 05, 2017 4:05 am

Image Gravity's Grin

Explanation: Albert Einstein's general theory of relativity, published over 100 years ago, predicted the phenomenon of gravitational lensing. And that's what gives these distant galaxies such a whimsical appearance, seen through the looking glass of X-ray and optical image data from the Chandra and Hubble space telescopes. Nicknamed the Cheshire Cat galaxy group, the group's two large elliptical galaxies are suggestively framed by arcs. The arcs are optical images of distant background galaxies lensed by the foreground group's total distribution of gravitational mass. Of course, that gravitational mass is dominated by dark matter. The two large elliptical "eye" galaxies represent the brightest members of their own galaxy groups which are merging. Their relative collisional speed of nearly 1,350 kilometers/second heats gas to millions of degrees producing the X-ray glow shown in purple hues. Curiouser about galaxy group mergers? The Cheshire Cat group grins in the constellation Ursa Major, some 4.6 billion light-years away.

<< Previous APOD This Day in APOD Next APOD >>

User avatar
Ann
4725 Å
Posts: 8308
Joined: Sat May 29, 2010 5:33 am

Re: APOD: Gravity's Grin (2017 Aug 05)

Postby Ann » Sat Aug 05, 2017 6:44 am


I knew it! Just a few days ago, I googled "gravity smiley" and found... :arrow:

Of course, the picture I found has no X-ray data.

The Curiouser links takes us to an arXiv paper from May 2015 by Jimmy A. Irwin, Renato Dupke, Eleazar R. Carrasco, W. Peter Maksym, Lucas Johnson and Raymond E. White III, which contains some interesting info:

The Cheshire Cat is a relatively poor group of galaxies dominated by two luminous elliptical galaxies surrounded by at least four arcs from gravitationally lensed background galaxies that give the system a humorous appearance.

I'll say! 8-)

Our combined optical/X-ray study of this system reveals that it is experiencing a line of sight merger between two groups with a roughly equal mass ratio with a relative velocity of ∼1350 km s−1.

That's fast, I suppose.

The collision manifests itself in a bimodal galaxy velocity distribution, an elevated central X-ray temperature...

Right.

The fossil Ida. Photo: Jørn Hurum.
Source: http://sciencenordic.com/fossil-ida-–-five-years
One group was most likely a low-mass fossil group, while the other group would have almost fit the classical definition of a fossil group.


So what's a fossil galaxy group?

Fossil groups are classically defined as systems dominated by a single giant elliptical galaxy for which there is at least a two magnitude difference between that galaxy and the second rank galaxy (in r-band) within 0.5 r200 (where r200 approximates the virial radius where the average mass density inside this radius is 200 times the critical density of the Universe), and are bright sources of extended X-ray emission (LX,bol > 1042h−250 erg s−1; Jones et al. 2003).


Read the small print if you are interested. But yes, the Cheshire Cat group is indeed dominated by two bright elliptical galaxies, and there are relatively few and faint galaxies surrounding them. And there is a lot of extended X-ray emission around them.

And in a cosmic blink of an eye, in only a billion years, the two "eyes" of the gravity smiley will merge. Will that make the Cheshire Cat grin disappear, I wonder?

Ann

Cheshire cat.png
You do not have the required permissions to view the files attached to this post.
Color Commentator

User avatar
orin stepanek
Plutopian
Posts: 4454
Joined: Wed Jul 27, 2005 3:41 pm
Location: Nebraska

Re: APOD: Gravity's Grin (2017 Aug 05)

Postby orin stepanek » Sat Aug 05, 2017 11:03 am

Wow; Gravity is just an emoji! :lol2: 8-) ; :wink:
Orin

Smile today; tomorrow's another day!

NCTom

Re: APOD: Gravity's Grin (2017 Aug 05)

Postby NCTom » Sat Aug 05, 2017 12:26 pm

Being neither a mathematician nor an astronomical physicist, I can only sit back and wonder at some of these "things" out there in the universe. One of those "things" is dark matter. The link "dark matter" goes to the LSST web site with additional connections to definitions of dark matter. Is dark matter (and dark energy) still a purely mathematical entity? Do we have such a clear understanding of gravity that we must postulate the existence of undetectable matter and energy to make it fit the rules of universal gravity? Is it possible there is still much we don't understand about gravity like why gravity at all? We know it is , but why is it. From a non scientific point of view dark matter sounds a lot like the theologian's "god of the gaps" theory.

User avatar
Chris Peterson
Abominable Snowman
Posts: 13044
Joined: Wed Jan 31, 2007 11:13 pm
Location: Guffey, Colorado, USA

Re: APOD: Gravity's Grin (2017 Aug 05)

Postby Chris Peterson » Sat Aug 05, 2017 1:27 pm

NCTom wrote:Being neither a mathematician nor an astronomical physicist, I can only sit back and wonder at some of these "things" out there in the universe. One of those "things" is dark matter. The link "dark matter" goes to the LSST web site with additional connections to definitions of dark matter. Is dark matter (and dark energy) still a purely mathematical entity? Do we have such a clear understanding of gravity that we must postulate the existence of undetectable matter and energy to make it fit the rules of universal gravity? Is it possible there is still much we don't understand about gravity like why gravity at all? We know it is , but why is it. From a non scientific point of view dark matter sounds a lot like the theologian's "god of the gaps" theory.

Dark energy is not well understood, and may fall to better explanations. Dark matter, however, is a different matter. It makes its presence known in many different ways, all consistent, and also helps explain the nature of the very early Universe. It behaves in a way that is consistent with normal matter in most respects, and as a particle isn't much different from other particles that we have observed, which only weakly interact with the electromagnetic force.

Is it possible that a changed understanding of gravity will replace dark matter? Certainly. Is it likely? No.
Chris

*****************************************
Chris L Peterson
Cloudbait Observatory
http://www.cloudbait.com

ta152h0
Schooled
Posts: 1219
Joined: Mon Aug 29, 2005 12:46 am
Location: Auburn, Washington, USA

Re: APOD: Gravity's Grin (2017 Aug 05)

Postby ta152h0 » Sat Aug 05, 2017 3:55 pm

does the light of each Eistein ring arrive here at the same time ? Or is it thinking too far out of the box ?
Wolf Kotenberg

User avatar
Chris Peterson
Abominable Snowman
Posts: 13044
Joined: Wed Jan 31, 2007 11:13 pm
Location: Guffey, Colorado, USA

Re: APOD: Gravity's Grin (2017 Aug 05)

Postby Chris Peterson » Sat Aug 05, 2017 4:10 pm

ta152h0 wrote:does the light of each Eistein ring arrive here at the same time ?

No. The path lengths from the source to the Earth are different, and therefore the arrival times are different. That's how we've observed single supernovas at different times along different lensed paths.
Chris

*****************************************
Chris L Peterson
Cloudbait Observatory
http://www.cloudbait.com

FLPhotoCatcher
Science Officer
Posts: 127
Joined: Wed Jul 18, 2012 6:51 am

Re: APOD: Gravity's Grin (2017 Aug 05)

Postby FLPhotoCatcher » Sat Aug 05, 2017 5:17 pm

I have wondered about gravity and dark matter and dark energy for some time now, and have (I think) come up with a somewhat crazy explanation. Actually, I think I heard a similar explanation on a science program.
Could gravity be from the strong nuclear forces acting on 'our' universe from an infinite number of slightly different alternate universes? The difference in the strength of gravity the farther you get from a mass (and thus strong nuclear forces) would be due to said mass in alternate universes (AUs) being diffused out in physical location from where it is in 'our' universe. Smaller masses would be more easily diffused in AUs than larger ones, thus creating weaker gravity.
Dark matter seen around galaxies would then be the diffused matter from those galaxies in countless AUs. The diffused matter would, naturally extend past the edges of visible galaxies, but be weakly attracted to itself, keeping it from flying away too far. This would explain the location of Dark matter.
Dark energy could also be explained - since distant galaxies do not diffuse extremely far from 'themselves' in AUs, they make, effectively, a limit to the reach of gravity created by ordinary atoms. If the universe is accelerating, it is due to the weak overall binding gravity of the universe, in addition to the repelling force of ordinary EM radiation.
Sound plausible?

User avatar
Chris Peterson
Abominable Snowman
Posts: 13044
Joined: Wed Jan 31, 2007 11:13 pm
Location: Guffey, Colorado, USA

Re: APOD: Gravity's Grin (2017 Aug 05)

Postby Chris Peterson » Sat Aug 05, 2017 5:22 pm

FLPhotoCatcher wrote:Sound plausible?

It would not qualify as "plausible" until someone could propose a way the idea could be tested. It would not offer a better explanation of current theory until some of those tests were performed and failed to disprove the idea.
Chris

*****************************************
Chris L Peterson
Cloudbait Observatory
http://www.cloudbait.com

Tszabeau

Re: APOD: Gravity's Grin (2017 Aug 05)

Postby Tszabeau » Sat Aug 05, 2017 5:56 pm

What's causing the object at the right of the frame to have X-ray glow?

NCTom

Re: APOD: Gravity's Grin (2017 Aug 05)

Postby NCTom » Sat Aug 05, 2017 9:35 pm

Thanks, Chris. I must admit I was hoping you would show up. If we already see dark matter acting and reacting in a manner consistent with many of the known attributes of our kind of matter, then there is hope we can some day give it a name besides "dark".

ta152h0
Schooled
Posts: 1219
Joined: Mon Aug 29, 2005 12:46 am
Location: Auburn, Washington, USA

Re: APOD: Gravity's Grin (2017 Aug 05)

Postby ta152h0 » Sat Aug 05, 2017 10:15 pm

does light have viscosity component to it ? I watched " how the universe works " all morning and prof Kaku, Krauss and Thaler were saying the universe is still accelerating outward and were discussing the cause.This is fascinating considering light permeates everything, at the speed of light.
Wolf Kotenberg

emailcrash@me.com

Re: APOD: Gravity's Grin (2017 Aug 05)

Postby emailcrash@me.com » Sat Aug 05, 2017 11:48 pm

WHERE'S HIS CAP?
WE ALL KNOW THAT THIS IS JUST A BIG JACK-IN-THE BOX AD!
Crash

User avatar
Chris Peterson
Abominable Snowman
Posts: 13044
Joined: Wed Jan 31, 2007 11:13 pm
Location: Guffey, Colorado, USA

Re: APOD: Gravity's Grin (2017 Aug 05)

Postby Chris Peterson » Sun Aug 06, 2017 12:31 am

NCTom wrote:Thanks, Chris. I must admit I was hoping you would show up. If we already see dark matter acting and reacting in a manner consistent with many of the known attributes of our kind of matter, then there is hope we can some day give it a name besides "dark".

Well "dark" is a pretty good name for it, since the main thing that seems to distinguish it from other matter is its lack of interaction with the electromagnetic force. It is, quite literally, dark.
Chris

*****************************************
Chris L Peterson
Cloudbait Observatory
http://www.cloudbait.com

FLPhotoCatcher
Science Officer
Posts: 127
Joined: Wed Jul 18, 2012 6:51 am

Re: APOD: Gravity's Grin (2017 Aug 05)

Postby FLPhotoCatcher » Sun Aug 06, 2017 1:05 am

Chris Peterson wrote:
FLPhotoCatcher wrote:Sound plausible?

It would not qualify as "plausible" until someone could propose a way the idea could be tested. It would not offer a better explanation of current theory until some of those tests were performed and failed to disprove the idea.


Well, it could be tested by making a random number generator that spits out a random number from 1 to 100. When the generator selects numbers 98 to 100 you would remove a heavy weight that was placed next to a very sensitive gravity sensor, and compare the gravity field to the gravity field measured before the weight was moved next to the sensor. Repeat several times, moving the whole test to random locations.
Don't a lot of scientists firmly believe in a multiverse? From people having a "6th sense" to other strange atomic behavior, the evidence does support the idea. If other universes somehow interact with our minds, why not the strong force with all matter?

User avatar
Chris Peterson
Abominable Snowman
Posts: 13044
Joined: Wed Jan 31, 2007 11:13 pm
Location: Guffey, Colorado, USA

Re: APOD: Gravity's Grin (2017 Aug 05)

Postby Chris Peterson » Sun Aug 06, 2017 4:18 am

FLPhotoCatcher wrote:
Chris Peterson wrote:
FLPhotoCatcher wrote:Sound plausible?

It would not qualify as "plausible" until someone could propose a way the idea could be tested. It would not offer a better explanation of current theory until some of those tests were performed and failed to disprove the idea.

Well, it could be tested by making a random number generator that spits out a random number from 1 to 100. When the generator selects numbers 98 to 100 you would remove a heavy weight that was placed next to a very sensitive gravity sensor, and compare the gravity field to the gravity field measured before the weight was moved next to the sensor. Repeat several times, moving the whole test to random locations.

I don't understand the test. We have made measurements of the gravitational constant to as fine a degree as our instrumentation currently makes possible (which is not very good compared with most other measurements of universal constants), and it has shown no variation with position, mass, or distance.

Don't a lot of scientists firmly believe in a multiverse?

I would say that very few scientists believe in such a thing. Because there is no evidence. It is highly speculative and nobody has a way to even test the idea. It's a mathematical abstraction that many find interesting, but not enough to rise to "belief".

From people having a "6th sense" to other strange atomic behavior, the evidence does support the idea. If other universes somehow interact with our minds, why not the strong force with all matter?

There is absolutely zero evidence supporting any "6th sense" (and it has been aggressively sought). And there is no "strange atomic behavior" that isn't better explained by other theories (not that the multiverse idea really rises to the level of scientific theory).
Chris

*****************************************
Chris L Peterson
Cloudbait Observatory
http://www.cloudbait.com

FLPhotoCatcher
Science Officer
Posts: 127
Joined: Wed Jul 18, 2012 6:51 am

Re: APOD: Gravity's Grin (2017 Aug 05)

Postby FLPhotoCatcher » Sun Aug 06, 2017 9:41 pm

Chris Peterson wrote:I don't understand the test. We have made measurements of the gravitational constant to as fine a degree as our instrumentation currently makes possible (which is not very good compared with most other measurements of universal constants), and it has shown no variation with position, mass, or distance.

The explanation of the test is this: If the heavy weight is removed due to a truly random number on the random number generator, it is likely to not have been removed in most AUs, meaning it's gravity may still be detectable with a sensitive detector. The weight may need to be in place for at least a month or so, and be removed very quickly, with the detector measuring constantly to detect any variation of what would normally be expected. I propose that gravity is the strong force "leaking through" from countless AUs where the masses are shifting (diffusing) in physical location due to differing laws of physics. The Earth may even be disintegrating into separate atoms in these AUs. This gradient of mass/strong force would then pull atoms toward this higher concentration that exists in the multiverse.

Chris Peterson wrote:I would say that very few scientists believe in such a thing. Because there is no evidence. It is highly speculative and nobody has a way to even test the idea. It's a mathematical abstraction that many find interesting, but not enough to rise to "belief". There is absolutely zero evidence supporting any "6th sense" (and it has been aggressively sought). And there is no "strange atomic behavior" that isn't better explained by other theories (not that the multiverse idea really rises to the level of scientific theory).

Scientists who support the idea include: Michio Kaku, Neil deGrasse Tyson, Leonard Susskind, and Stephen Hawking, to name just a few. In the traditional Copenhagen interpretation of quantum mechanics, the wave function is said to “collapse” when the measurement is taken, but it isn’t clear how this happens. In the multiverse, the wave function never collapses: rather, it describes the property across multiple universes. In this universe, the atom’s spin is up; in another universe, it’s down. Schrödinger posited that until you look, his famous cat exists simultaneously in two quantum states, one living and one dead. Hugh Everett posited that when we open the box and look, all that really happens is we learn which of the two living/dead cat universes we happen to be in.
It was Hugh Everett who devised the many-worlds interpretation of quantum mechanics. The theory sounds like a bizarre hypothesis, but in fact Everett derived it from the fundamental mathematics of quantum mechanics. The "Many Interacting Worlds interpretation" is a recent similar theory. This theory (or hypothesis) explains why, in the classic two-slit experiment, light (and even atoms) exhibit self interference, and why particles can occasionally “tunnel” through insurmountable barriers as though they weren’t there at all. The two-slit experiment is one piece of evidence for AUs.

And there is some evidence of "precognition". http://hplusmagazine.com/2010/11/04/pre ... -mind-can/
Yes, evidence for it has been "aggressively sought" (by a relative few), but the very idea of it has most certainly been aggressively, and most unscientifically, mocked and buried. We all have probably been directly or indirectly influenced by people like Lee Nisbet, former Executive Director of CSICOP. He said, “[Belief in psi is] a very dangerous phenomenon. Dangerous to science, dangerous to the basic fabric of our society… We feel it is the duty of the scientific community to show that these beliefs are utterly screwball.” But that kind of thinking is dogma, not a trait a fair-minded scientist should have.

The Many Interacting Worlds theory is not just something to seriously consider for the sake of truth, but, "if, for instance, the interaction of different universes could influence the speed of a chemical reaction, then knowing the mechanics of how those universes interact could help with virtually any area of modern science. A more precise and far-seeing way to predict how quantum phenomena will proceed could impact everything from industrial processes to quantum cryptography." Quantum computing would be another use of the effects of Many Interacting Worlds.
Scientists, and thinkers in general, seem to want to desperately quash the idea of "many worlds", probably because it seems almost like a religion, but also because it could have serious social consequences. Some may fear that if it was accepted by the public, people would jump off buildings and do other crazy things, knowing they were basically immortal. But while they may survive (from their perspective), their quality of life may best be described as 'hell on earth'. This could be grasped by all - surviving as a quadriplegic or a head in a jar would not be fun or painless.

User avatar
Chris Peterson
Abominable Snowman
Posts: 13044
Joined: Wed Jan 31, 2007 11:13 pm
Location: Guffey, Colorado, USA

Re: APOD: Gravity's Grin (2017 Aug 05)

Postby Chris Peterson » Sun Aug 06, 2017 10:17 pm

FLPhotoCatcher wrote:Scientists who support the idea include: Michio Kaku, Neil deGrasse Tyson, Leonard Susskind, and Stephen Hawking, to name just a few.

There is a massive difference between supporting an idea and believing it to represent reality.

It's pretty simple. If a person says they believe in mulitverses, I would argue they are not a competent scientist. That does not mean that exploring the concept isn't a legitimate scientific avenue.

In the traditional Copenhagen interpretation of quantum mechanics, the wave function is said to “collapse” when the measurement is taken, but it isn’t clear how this happens.

It is a fallacy to believe that "how" (in the sense you use it here) is necessarily a valid question in many cases.

And there is some evidence of "precognition". http://hplusmagazine.com/2010/11/04/pre ... -mind-can/

Extremely unconvincing. I note that it's unreplicated after seven years, and the authors later papers are largely unpublished. I would argue that this is actually evidence that the effect doesn't exist.
Chris

*****************************************
Chris L Peterson
Cloudbait Observatory
http://www.cloudbait.com

K1NS

Re: APOD: Gravity's Grin (2017 Aug 05)

Postby K1NS » Fri Aug 11, 2017 12:17 am

I have a picture of a gravitational lensing as the wallpaper on my smartphone, so I have a lot of chances to study the image. As in the "grin" posted today, you can see a lot of detail in the arc images of the distant galaxies.

Has anyone tried applying an algorithm to the images to convert it back to its original form? Think of the compensating lens they put on the Hubble telescope years ago. You could apply a compensating algorithm and get an correctly proportioned image of the distant galaxy, as if the "lensing matter" were not in between.

What do you think? Could this be done?

User avatar
Chris Peterson
Abominable Snowman
Posts: 13044
Joined: Wed Jan 31, 2007 11:13 pm
Location: Guffey, Colorado, USA

Re: APOD: Gravity's Grin (2017 Aug 05)

Postby Chris Peterson » Fri Aug 11, 2017 12:28 am

K1NS wrote:I have a picture of a gravitational lensing as the wallpaper on my smartphone, so I have a lot of chances to study the image. As in the "grin" posted today, you can see a lot of detail in the arc images of the distant galaxies.

Has anyone tried applying an algorithm to the images to convert it back to its original form? Think of the compensating lens they put on the Hubble telescope years ago. You could apply a compensating algorithm and get an correctly proportioned image of the distant galaxy, as if the "lensing matter" were not in between.

What do you think? Could this be done?

http://hubblesite.org/news_release/news/2012-08

However, it requires just the right conditions, and knowledge of the distribution of the lensing dark matter (since the lens is "lumpy", and they're all different).
Chris

*****************************************
Chris L Peterson
Cloudbait Observatory
http://www.cloudbait.com


Return to “The Bridge: Discuss an Astronomy Picture of the Day”

Who is online

Users browsing this forum: Ahrefs [Bot], CommonCrawl [Bot], neufer and 2 guests