Physics Discussion Thread

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UlanBatori
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Re: Physics Thread.

Postby UlanBatori » 19 Feb 2016 06:41

The whole SOP of LIGO reminds me of the Don MacLean song: Prime Time

My supper's on the stove, the LIGO's is on the screen
Pass the bread and butter while I watch the Marine
The shot him in the chest--Pass the chicken breast!
The general is saying that he's still unimpressed.
"We had to burn the city 'cause they wouldn't agree
That things go better with democracy!"
The weather will be fair, forget the ozone layer,
But strontium showers and Black Holes will be here and there


Here's my Peace Offering to the LIGOtists: A really spectacular sketch of gamma rays shooting out.

But now a Gamma Ray Burst (GRB) originating from the same place, and that arrived at Earth 0.4 seconds after the GW, is making news. Isolated black holes aren’t supposed to create GRB’s; they need to be near a large amount of matter to do that.


This is what I was hoping to read: that someone saw something else in the same place where this humongous SpaceTime Quake occurred. But.. they are not sure.

NASA’s Fermi telescope detected the GRB, coming from the same point as the GW, a mere 0.4 seconds after the waves arrived. Though we can’t be absolutely certain that the two phenomena are from the same black hole merger, the Fermi team calculates the odds of that being a coincidence at only 0.0022%. That’s a pretty solid correlation.

So what’s going on here? To back up a little, let’s look at what we thought was happening when LIGO detected gravitational waves.

Our understanding was that the two black holes orbited each other for a long time. As they did so, their massive gravity would have cleared the area around them of matter. By they time they finished circling each other and merged, they would have been isolated in space. But now that a GRB has been detected, we need some way to account for it. We need more matter to be present.

According to Abraham Loeb, of Harvard University, the missing piece of this puzzle is a massive star—itself the result of a binary star system combining into one—a few hundred times larger than the Sun, that spawned two black holes. A star this size would form a black hole when it exhausted its fuel and collapsed. But why would there be two black holes?

Again, according to Loeb, if the star was rotating at a high enough rate—just below its break up frequency—the star could actually form two collapsing cores in a dumbbell configuration, and hence two black holes. But now these two black holes would not be isolated in space, they would actually be inside a massive star. Or what was left of one. The remnants of the massive star is the missing matter.

When the black holes joined together, an outflow would be generated, which would produce the GRB. Or else the GRB came “from a jet originating out of the accretion disk of residual debris around the BH remnant,” according to Loeb’s paper. So why the 0.4 s delay? This is the time it took the GRB to cross the star, relative to the gravitational waves.

It sounds like a nice tidy explanation. But, as Loeb notes, there are some problems with it. The main question is, why was the GRB so weak, or dim? Loeb’s paper says that “observed GRB may be just one spike in a longer and weaker transient below the GBM detection threshold.”

But was the GRB really weak? Or was it even real? The European Space Agency has their own gamma ray detecting spacecraft, called Integral. Integral was not able to confirm the GRB signal, and according to this paper, the gamma ray signal was not real after all.

As they say in show business, “Stay tuned.”

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Re: Physics Thread.

Postby UlanBatori » 19 Feb 2016 06:52

Related pooch that I have: This GW-quake must have ABSOLUTELY shattered things in its general vicinity. I mean, if you were 0.1 light year away, your world would have been torn apart by it. Like an earthquake of magnitude 270 on the Richter Scale. Or 2700. or 270000. Unimaginable.

Wouldn't THOSE have :(( , radiating all sorts of flashes and blinks?

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Re: Physics Thread.

Postby member_29325 » 19 Feb 2016 07:06

At 0.1 light years away, the earthquake would probably be accompanied by X-ray and gamma ray emissions of fatal proportions and wipe out all life as everything is ripped apart, just like how it was before baby superman was put into a spaceship and sent to Kansas by Richard burton.

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Re: Physics Thread.

Postby Amber G. » 19 Feb 2016 07:32

vayu tuvan wrote:I think the papers were already written and ready to go the moment they detect the signal. All they had to do was to plug in the signal strengths and other stats data and write up the conclusion(s) and off the papers go to Science/Nature/PRL etc.

Original signal was detected in September, and right away the preliminary calculations told them to take deeper look at data.... It took them months of checking and rechecking to reach the confidence level they reached. Meanwhile there were few more events detected .. good enough (less than 2-3% chance that it was false positive) but it was not broadcasted. ... but why let facts get in the way of conspiracy theories..

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Re: Physics Thread.

Postby Amber G. » 19 Feb 2016 07:56

Ok.. this will make all these Truthers, conspiracy theorists and madrasa math experts jumping with excitement ..
read all about it...
Truthers Think Gravity Waves Are a Hoax to Convince Us the World Is Round
Not one week after physicists confirmed the existence of gravitational waves, the conspiracy theorists are out in force, shouting to the heavens that the “breakthrough” was a lie invented by fame-hungry scientists, supported by money-hungry institutions, and regurgitated by the traffic-hungry news media. (Sounds familiar .. :-o )

:eek: All to keep you from seeing the bigger lie—gravity itself! :eek: The corporate physics elite, drunk on the power of being able to write the laws of nature as it sees fit, have built a prison for our minds, my friends.
Is Einstein turning over in his grave? Who cares, he’s probably one of Them. :rotfl:



Enjoy!

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Re: Physics Thread.

Postby Bade » 19 Feb 2016 08:57

WOW ! This thread is an indicator of what is wrong with the world...I thought indics were not part of this mania of CTs, but now I am 400% sure that pakis==indics. Barf generators in full flow here. I thought of summarizing what I heard but it is more fun to do CT and counter-CT....welcome to NaMo's world like Wayne's world. :rotfl: :rotfl: :rotfl:

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Re: Physics Thread.

Postby Bade » 19 Feb 2016 09:01

FERMI-LAT news has reached here too I see....wah wah ! It is hardly a 5sigma signal to go to town yet. There is talk, but that is like that the upcoming 750GeV bump to be confirmed....wait till the summer for real news than rumours.

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Re: Physics Thread.

Postby A_Gupta » 19 Feb 2016 09:25

vayu tuvan wrote:UB ji: What is infinite velocity? the limit is c (speed of light). Curvature is second derivative of velocity (or first derivative of acceleration).

Now I come to TSJ's assertion that the curvature is infinite at a BH. How is that possible? Is it because EM energy trapped in the black hole can never make it out of the BH? Words, words, words. How I hate descriptive physics!


1. Dunno where "infinite velocity" came from.
2. Curvature in the context of general relativity or blackholes refers to curvature of space-time.
3. Since 4-dimensional spacetime is an unfamiliar thing, think of the surface of a ball. It is curved.
4. The 2-dimensional surface of a ball is certainly curved with respect to the 3-dimensional space it is immersed in; but you would be able to figure out it was curved merely from measurements taken on its surface. (Hint available here: http://nrich.maths.org/5654 ) Spacetime is similarly curved without being immersed in anything.
5. What is a curvature singularity in 2-dimensions? Think of the surface of a cone. There is a some kind of a curvature singularity at the apex of the cone. The curvature is infinite at that point.
6. There is a curvature singularity at the center of the blackhole. However, the event horizon keeps us from being able to see it, because nothing from inside the event horizon gets outside.
7. There is a singularity at the beginning of the Big Bang, too. There is no event horizon shielding us from it.
8. As Wiki tells you: "The weak cosmic censorship hypothesis was conceived by Roger Penrose in 1969 and posits that no naked singularities, other than the Big Bang singularity, exist in the universe."
9. Classical physics contains other singularities as well, such as in the electric field of a point charge at the position of the charge is infinite.
10. Throw quantum physics into the mix, and the classical singularity of the electric charge goes away. Physicists expect that something like that will happen if we had a good theory of quantum gravity.
11. Other interesting things happen when you start throwing in quantum mechanics with general relativity. It turns out that a black hole behaves like the classical blackbody - it radiates with a blackbody spectrum. Blackholes have entropy too. There are still unsolved paradoxes around these.

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Re: Physics Thread.

Postby Vayutuvan » 19 Feb 2016 10:40

UlanBatori wrote:
Potential theory again predicts an infinite velocity and infinite velocity gradient (discontinuity) at the singularity where the vortex center is located. The finite-diameter core is a later refinement.

Infinite velocity came from this post. 4d space time is not unfamiliar it is unvisualuzable. So I stop visualizing it and simply think in terms of the equations and identities and functions. Very similar to looking at emission spectrum of an astronomical object. Why make the effort in visualizing at all?

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Re: Physics Thread.

Postby A_Gupta » 19 Feb 2016 16:21

vayu tuvan wrote:
UlanBatori wrote:
Potential theory again predicts an infinite velocity and infinite velocity gradient (discontinuity) at the singularity where the vortex center is located. The finite-diameter core is a later refinement.

Infinite velocity came from this post. 4d space time is not unfamiliar it is unvisualuzable. So I stop visualizing it and simply think in terms of the equations and identities and functions. Very similar to looking at emission spectrum of an astronomical object. Why make the effort in visualizing at all?


Arguably, physics advances with physical insight, not with mathematics.
http://arxiv.org/abs/1512.07551
"Lessons from Einstein's 1915 discovery of general relativity"

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Re: Physics Thread.

Postby UlanBatori » 19 Feb 2016 16:58

JFYI: [***sanity break**]
V do get copies of ScientificMongolian in my cave ... useful to keep warm in winter. IIRC there was an issue dealing with the famous scientist EkPatthar and his Relatives. One cousin far removed was this business of space-time, I think. However, one cannot just run away from one theory and say, aha! but you should be looking at this other theory! AFAIK, simpler linearized theories must hold right up close to the Event Horizon - as they do in any classical potential theory (and motion in a gravitational field is certainly/ potentially right up there in potential energy!) :P

Since I am firmly pawed in the Mongolian Frame of Reference, I have to express everything else from that pov. So the Lorentz Transform holds: For the uneducated/ pissikally conphyoojed mathematical genii: pls see Wikipedia, Authoritative Source on Jarnail Relative and even Brigadier-Jarnail Relatives. See "lowercase gamma", aka Lorentz Factor and all will become (relatively) clearer than looking through 1.5 billion light years of dust clouds and galaxies. To see a humongous compression-expansion (what else is a "gravitational wave"?) that apparently left all of them not even moving, let alone emitting :(( :((

For analogies to supersonic potential flow see here & use some imagination [\end***sanity break**]

OK! Back 2 our regular programming! :mrgreen:

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Re: Physics Thread.

Postby UlanBatori » 19 Feb 2016 17:11

Regular programming:
The hype says that this wonderful template signal came from the merger of two Black Holes. But then they claim that each Black Hole was a collapsed SINGLE STAR!!!!! That's an insignificant Black Hole, hain? If it burned out so fast and started gravitational collapse inside a mere <<< 14B years! Our Sun, no giant, has been around for at least 4B years, and no great change seen for the last couple of billion, AFAIK.

So to continue that line of thought: At the center of the Rasta-e-Doodh, is a giant BH. It has presumably eaten MANY stars. Shouldn't EACH of those stellar mergers have induced a much bigger GW than this? IOW, shouldn't GWs from closer places than 1.5B light years be coming around practically every day, if just the merger of TWO stellar masses induced such huge GW melas?

There are collisions between galaxies in progress as we speak(I mean in shifted time, but visible today) Shouldn't there be huge GWs accompanying every stellar collision there?

Perhaps that was at the time of a long-past budget renewal Event (BRE)?

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Re: Physics Thread.

Postby TSJones » 19 Feb 2016 18:47

...we have to be careful of our assumptions....

we don't know what was in the immediate neighborhood when these black holes were formed.

nor do we know how much material was already cleared when the two black holes formed.

we do know that any material sufficiently close to the event horizon gets gulped down. but what of the other material farther away?

we know that black hole gravity attraction works like any other gravitational body at a sufficient enough distance.

for instance we know that the planet Mercury is no danger of being gulped down by our sun and that our galaxy is no danger of being eaten by its black hole.

having said that, I understand there is a lot of difference in gravity pull of our sun vs. a black hole, but still, orbital decay math prolly works the same even though i am a dunce don't know how to use it.

could be wrong and probably am. JMT.

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Re: Physics Thread.

Postby UlanBatori » 19 Feb 2016 20:58

we don't know what was in the immediate neighborhood when these black holes were formed.

Fermilab/NASA number says Gamma Rays reached 0.4 second after Big Whoosh-Gurgle. That means that whatever became shaheed was located 0.2x300,000km = 60,000km to the other side of the BH-Merger. (0.2 second to go that way and 0.2 second for the GW to come back this way) That's extremely close! The Moon is, what - 320,000 km from Earth?
Once I was called into the Office to answer a question over the telephone (allegedly) from the Free Biscuits Institution:
Is it true that the Moon is 200 miles from Earth?
:eek:

So how can they claim that these BHs had nothing in the vicinity, hain? Fishee! Fishee!!

I think the whole notion of an Isolated Black Hole is fundamentally bogus. Vortices (that's plural of "vortex" for the physicists) become unstable the moment the pressure gradient stops being favorable. If they try to slow down the spin they "burst". The BH, being a vortex, will start slowing down as the matter all gets scrunched inside the SuperOptic Region (aka Core of the BH, inside the Event Horizon). It will also heat up. It must be the (infinite) gravity of the entering material at the Event Horizon that keeps the SuperOptic Region stable. Once the mass influx stops, Boom!
Wonder what EkPatthar Khan had to say about this.

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Re: Physics Thread.

Postby Vayutuvan » 19 Feb 2016 21:59

TSJ: the energy landscape of the universes is not smooth. As one goes further away from a massive body, scondary effects start dominating and change the local gravitational field. The field is different at every point in space or should it be called spacetime?

UB: I thought that there was no time nor matter when the BWG happened. What exactly is distance when there is no time unless we are talking about negative time or the complementary time cone to the one we are in.

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Re: Physics Thread.

Postby Vayutuvan » 19 Feb 2016 22:03

A_gupta: Lorenz contraction is easy to understand through the equations as well as the mass approaching infinity. Unless one understands the mathematical abstractions any amount of physical insight would be insufficient. Simple example is Bhaskara's wheel or other proposed perpetual motion machines.

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Re: Physics Thread.

Postby UlanBatori » 19 Feb 2016 22:19

UB: I thought that there was no time nor matter when the BWG happened. What exactly is distance when there is no time unless we are talking about negative time or the complementary time cone to the one we are in.


Noooooo! It's only 1.5B years ago - that's almost when Mohenjodaro had semi-annual naatch-geet/goat-halal festivals onlee! Life on Earth is ~ 1 B saal old, hain? (Oh, WAIT! 4.5B years old!) :shock: Our ol' Sun is >4B years old by Binaori Madarssa String and Goat Bifurcation Theory per the Abdul Bin Schrodinger ki Billi equation, I think.

Which of course brings up the possibility: Could the BWG have been ATM flushing the great pakistan in the aajman? :eek: :shock: They may not have had lotas in those days... These LEGO ppl just don't have a good enough library of Templates - give them another few $$B!

This is not as re-lie-able as Wikipedia but we yak-herds can't be choosers:
G.J. Wasserburg obtained a meteoritic age of (4.57 +/- 0.01) x 10^9 years and D.B. Guenther (1989, Astrophysical Journal 339, 1156) estimated that hydrogen burning started shortly thereafer (40 million (0.04 +/- .01) x 10^9 years later).

Additional evidence comes from the Earth. The oldest Earth rocks are also about 4.6 billion years old. The oldest fossils, found in Australia, are about 3.5 bilion years old. The presence of fossils in rocks indicates that the Earth was a suitable place for life when the fossils formed. This implies that the Sun was luminous at that time. [Of course we can't say exactly how long before the fossil formed the Sun was like it is today, but it does give us a lower bound.]

What is meant by "luminous?" We mean that the Sun was at or near the stable part of its lifetime called the "main sequence" more than 3.6 billion years ago.


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Re: Physics Thread.

Postby Amber G. » 20 Feb 2016 03:03

Bade wrote:WOW ! This thread is an indicator of what is wrong with the world...I thought indics were not part of this mania of CTs, but now I am 400% sure that pakis==indics. Barf generators in full flow here. I thought of summarizing what I heard but it is more fun to do CT and counter-CT....welcome to NaMo's world like Wayne's world. :rotfl: :rotfl: :rotfl:


WOW indeed! Sorry I started it by posting the news, and a link to PRL and my (as a physicist's) perspective. I though it will be appreciated, get some decent discussion going but the feedback I got is like all I did was blasphemy. :rotfl: I knew the general public and ddm's have little understanding but was still surprised at the sheer CT mania in brf and would agree that pakis=indics and more if one just looks at this brf dhaga. I am archiving the dhaga. This, no exaggeration, will beat the best madrasa math and jinn thermodynamics type posts I have seen - :rotfl: - and I have seen quite a bit lurking in unmentionable forums. :rotfl:.. Only difference I see is, ignorance here is coupled with pompous arrogance, and outright contempt for logic, in some of the posts and most aam junta, it seems, can not even differentiate between madarasa math and simple math. :!: With just a few exceptions like A Gupta - many/most are indeed impressed with even the most ridiculous CT claims... (Just to document I may post one or two gems for the record).

May be its time to be quiet among chatter of frogs and sit back and enjoy. :rotfl:

UBji and JohneeG .. Please carry on..

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Re: Physics Thread.

Postby member_29325 » 20 Feb 2016 03:12

A_Gupta wrote:Arguably, physics advances with physical insight, not with mathematics.


Pretty sure that is the case. Pure Mathematicians are sometimes not the right people to teach more advanced mathematics -- the ones I have encountered have no idea that most of the mathematics they are talking about is motivated from wanting to model some abstraction in physics. Various quarks were mathematically predicted long before they were encountered in cyclotrons, which took a lot longer to build, so this LIGO results are not the first where the results from theoretical physics were used to validate the success of the experiment.

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Re: Physics Thread.

Postby TSJones » 20 Feb 2016 05:05

the problem, err opportunity, is that black holes don't always work the way we want them to.

the ornery things sometimes just go to "sleep":

http://news.discovery.com/space/galaxie ... 130611.htm

there is a lot of 'splaining to do in the universe...........

and the moon is moving away from earth 1,5 inches per year. it means the moon was a lot closer sometimes in the past.

still trying to grok that......

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Re: Physics Thread.

Postby UlanBatori » 20 Feb 2016 05:39

Phew! I've been allowed to "go on". ATM be praised! Pompously arrogantly speaking, TSJi, per a famous (not in pissiks circles) Flight Controls person, the Moon used to spin in the distant past. But it has a highly asymmetric mass distribution; i.e., density asymmetry. So each time the denser side came to face the Earth, gravity was much stronger than when the other side faced. So eventually that resulted in the spin stopping, which is why we don't see the far side of the Moon unless we go there. That sounds pretty drastic. If this happens to Earth, the side of the Earth inhabited by the greater Authorities on Pissicks will grab the Sunny Side, like the Physicist side of Mercury. We with the low-density brains will be on the dark side, enjoying views of the night sky.

So based on the above, I would have expected the Moon to be gradually drawing closer until it was, say, 200 miles from Earth :eek: One could then float up towards the Moon on a broomstick like in the fairy tales. Of course, one of dem sleeping Isolated BHs might come zipping by and end all our troubles in a flash: absolutely no warning at all. What a way to go!

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Re: Physics Thread.

Postby UlanBatori » 20 Feb 2016 06:08

This smells more fishy than a celebration on the Hooghly river.

Call it a gut reaction. The revolutionary discovery of space-time ripples may have come from two black holes colliding while inside the belly of an enormous star, :rotfl: whose subsequent collapse launched powerful jets of gamma rays.

Scientists already knew that the gravitational waves detected by LIGO, the Laser Interferometer Gravitational-Wave Observatory, were generated when two black holes – each about 30 times as massive as the sun – spiralled around each other and merged.

But now it seems that collision may have been followed by a bright burst of gamma rays. NASA’s Fermi gamma-ray space telescope detected such an eruption just 0.4 seconds after LIGO’s gravitational waves arrived at Earth. It’s not clear whether the same event triggered both signals, but the Fermi team calculated that the probability of a coincidence was just 0.0022.

The problem is that no one expected such a bright gamma-ray burst to accompany a black-hole merger. Coalescing black holes orbit each other in a cosmic do-si-do, clearing out a region of empty space. According to models of gamma-ray bursts, isolated black holes can’t ignite them.
Strange signal

Everything smells {U can say that again} like a short gamma-ray burst in our signal,” says Valerie Connaughton of the Fermi team. “And that’s a real problem in a way – you don’t expect this signal from merging black holes.”

But when Avi Loeb of Harvard University saw the Fermi results, he realised he knew You could get a gamma-ray burst if the two black holes were enveloped inside a very massive star. “It’s sort of like a pregnant woman with twins in her belly,” he says. {Don't u love the mathematical precision of these pisskist's explanations?} Once the black holes merged, the star would collapse and trigger intense beams of gamma rays.

For that to happen, the two black holes would have to have formed inside an extremely massive star a few hundred times heftier than the sun. As the star exhausted its nuclear fuel, its core began to collapse. Normally that would form a single black hole.

But if the star were rotating very fast, centrifugal force would stretch the collapsing core, shaping it into a dumbbell. Eventually, the dumbbell would snap into two cores, each of which would continue to collapse into its own black hole.
New ideas needed

“The only way to explain the Fermi signal is to surround the black holes with a lot of dense material, and the obvious way to do that, as in Loeb’s idea, is to put them inside a star,” says Dan Maoz of Tel Aviv University in Israel. “Maybe there are other ideas, but we need to think them up.”

It’s too soon to know whether this idea is right. Even Fermi’s results are in doubt: researchers analysing data from the European gamma-ray spacecraft, INTEGRAL, couldn’t corroborate Fermi’s finding, and concluded that the gamma ray signal is not real.

But even if this gamma-ray signal proves to be non-existent, there could be real ones in the future that coincide with a LIGO event, Loeb says. “We shouldn’t have a prejudice that black hole binaries are always silent in terms of their electromagnetic signature.” Astronomers should be on the lookout.

Journal reference: arxiv.org/abs/1602.04735

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Re: Physics Thread.

Postby member_29325 » 20 Feb 2016 06:38

For that to happen, the two black holes would have to have formed inside an extremely massive star a few hundred times heftier than the sun. As the star exhausted its nuclear fuel, its core began to collapse. Normally that would form a single black hole.


It is not completely surprising (to me) that they do not know the origin of the detected wave (assuming that it detected right) since the signal could have been from anywhere. Seems to demand more such LIGOs in space so that we can associate astronomical events with such signals, which is probably decades away, assuming govts. that currently fund these projects are not run by anti-science people in the future, as that could very well happen, given that majority of the human populace is turning more and more religious these days.

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Re: Physics Thread.

Postby UlanBatori » 20 Feb 2016 07:12

Suppose a giant AG* ship came by close enough so that their hi-res binoculars saw Sarah Palin and Shrilleen and Hillary, and suddenly put their Twin-Engine Warp Drive on max afterburners to fly away. Couldn't that explain the BWG? :eek:

* anti-gravity

OK.. b4 the polis-e-dhaga lathi-charge, here is the actual abstract of THE paper Itself, posted in full (again?)

Observation of Gravitational Waves from a Binary Black Hole Merger
B. P. Abbott
etal.
*
(LIGO Scientific Collaboration and Virgo Collaboration)
(Received 21 January 2016; published 11 February 2016) On September 14, 2015 at 09:50:45 UTC the two detectors of the Laser Interferometer Gravitational-Wave Observatory simultaneously observed a transient gravitational-wave signal. The signal sweeps upwards in frequency from 35 to 250 Hz with a peak gravitational-wave strain of 1.0×10−21. It matches the waveform predicted by general relativity for the inspiral and merger of a pair of black holes and the ringdown of the resulting single black hole. The signal was observed with a matched-filter signal-to-noise ratio of 24 and a false alarm rate estimated to be less than 1 event per 203 000 years, equivalent to a significance greater than 5.1σ. The source lies at a luminosity distance of 410þ160−180Mpc corresponding to a redshift z¼ 0.09þ0.03−0.04. In the source frame, the initial black hole masses are 36þ5−4M⊙ and 29þ4−4M⊙, and the final black hole mass is 62þ4−4M⊙, with 3.0þ0.5−0.5M⊙c^2
radiated in gravitational waves. All uncertainties define 90% credible intervals. These observations demonstrate the existence of binary stellar-mass black hole systems. This is the first direct detection of gravitational waves and the first observation of a binary black hole merger


* You can't use "et al" in NSF proposals.

This bounds the sum of the Schwarzschild radii of the binary components to 2GM=c^2≳210km. :eek: To reach an orbital frequency of 75 Hz (half the gravitational-wave frequency) the objects must have been very close and very compact; equal Newtonian point masses orbiting at this frequency would be only ≃ 350 km apart. :eek: :eek: A pair of neutron stars, while compact, would not have the required mass, while a black hole neutron star binary with the deduced chirp mass would have a very large total mass, and would thus merge at much lower frequency. This leaves black holes {or a flushing pakistan} as the only known objects compact enough to reach an orbital frequency of 75 Hz without contact. Furthermore, the decay of the waveform after it peaks is consistent with the damped oscillations of a black hole relaxing to a final stationary Kerr configuration.


So basically all they know is that SOMETHING emitted a signal rising in frequency and amplitude for a short time, amidst a lot of noise. The something was powerful enough to shake the sensitive beams at the LIGO facilities.

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Re: Physics Thread.

Postby UlanBatori » 20 Feb 2016 07:35

The Agreeable 1004 list is at the back of the paper.

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Re: Physics Thread.

Postby TSJones » 20 Feb 2016 07:36

200 miles from Earth


viola! so they were right in their guesstimate...........some time ago..........

Flight Controls person, the Moon used to spin in the distant past. But it has a highly asymmetric mass distribution; i.e., density asymmetry. So each time the denser side came to face the Earth, gravity was much stronger than when the other side faced. So eventually that resulted in the spin stopping, which is why we don't see the far side of the Moon unless we go there.


wow, really? :eek:

I just knew there had to be a reason why we only saw one side of the moon! :twisted:
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Re: Physics Thread.

Postby UlanBatori » 20 Feb 2016 07:38

ACKNOWLEDGMENTS
The authors gratefully acknowledge the support of the United States National Science Foundation (NSF) for the construction and operation of the LIGO Laboratory and Advanced LIGO as well as the Science and Technology Facilities Council (STFC) of the United Kingdom, the Max-Planck Society (MPS), and the State of Niedersachsen, Germany, for support of the construction of Advanced LIGO and construction andoperation of the GEO600 detector. Additional support for Advanced LIGO was provided by the Australian Research Council. Theauthors gratefullyacknowledge the Italian Istituto Nazionale di Fisica Nucleare (INFN), the French Centre National de la Recherche Scientifique (CNRS), and the Foundation for Fundamental Research on Matter supported by the Netherlands Organisation for Scientific Research, for the construction and operation of the Virgo detector,and for the creation and support of the EGO consortium :rotfl: . The authors also gratefully acknowledge research support from these agencies as well as by the Council of Scientific and Industrial Research of India, Department of Science and Technology, India, Science & Engineering Research Board (SERB), India, Ministry of Human Resource Development, India, the Spanish Ministerio de Economía y Competitividad, the Conselleria d’Economia i Competitivitat and Conselleria d’Educació, Cultura i Universitats of the Govern de les Illes Balears, the National Science Centre of Poland, the European Commission, the Royal Society, the Scottish Funding Council, the Scottish Universities Physics Alliance, the Hungarian Scientific Research Fund (OTKA), the Lyon Institute of Origins (LIO), the National Research Foundation of Korea,
Industry Canada and the Province of Ontario through the Ministry of Economic Development and Innovation, the Natural Sciences and Engineering Research Council of Canada, Canadian Institute for Advanced Research, the Brazilian Ministry of Science, Technology, and Innovation, Russian Foundation for Basic Research, the Leverhulme Trust, the Research Corporation, Ministry of Science and Technology (MOST), Taiwan, and the Kavli Foundation. The authors gratefully acknowledge the support of the NSF, STFC, MPS, INFN, CNRS and the State of Niedersachsen, Germany, for provision of computational resources and to the Ulan Bator Conspiracies and News Inc for Expert Peer Review. This article has been assigned the document numbers LIGO- P150914 and VIR-0015A-16.
Last edited by UlanBatori on 20 Feb 2016 07:47, edited 1 time in total.

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Re: Physics Thread.

Postby UlanBatori » 20 Feb 2016 07:45

wow, really? :eek:
I just knew there had to be a reason why we only saw one side of the moon! :twisted:

Really. He chuckled, said that they had used all these sophisticated pissiks and math with astronomical observations and Control simulations and eventually come out with what should have been a "duh!" answer. (That's why he was telling me.. :mrgreen: )

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Re: Physics Thread.

Postby UlanBatori » 20 Feb 2016 07:52

Efforts are under way to enhance significantly the global gravitational-wave detector network [117]. These include further commissioning of the Advanced LIGO detectors to reach design sensitivity, which will allow detection of binaries like GW150914 with 3 times higher SNR. Additionally, Advanced Virgo, KAGRA, and a possible third LIGO detector in India *[118] will extend the network and significantly improve the position reconstruction and parameter estimation of sources.


{*It will be tested with such large-amplitude-limit signals as Jayalalithaa jumping up and down}

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Re: Physics Thread.

Postby UlanBatori » 20 Feb 2016 07:55

Finally, assuming a modified dispersion relation for gravitational waves [97], our observations constrain the Compton wavelength of the graviton to be λ g>10^13km, which could be interpreted as a bound on the graviton mass mg< 1.2×10^−22eV/c^2.


Hi aces, how much is that Graviton Mass in kilograms, pls?

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Re: Physics Thread.

Postby member_29325 » 20 Feb 2016 08:00

UlanBatori wrote:So basically all they know is that SOMETHING emitted a signal rising in frequency and amplitude for a short time, amidst a lot of noise. The something was powerful enough to shake the sensitive beams at the LIGO facilities.


The paper claims they know a whole lot more, including where and what happened...don't get it, how did even know which direction the waves came from with just 2 LIGO detectors and what exactly happened? Brain too small to understand this magic obviously. if the gravitational waves are inert for the most part, the source could have been on the other side of the planet and done the job just as well.

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Re: Physics Thread.

Postby UlanBatori » 20 Feb 2016 08:21

Well... they seem to be saying that what appears to be background noise in the LIGO signal, may be due to all the BHs and neutron stars doing hootchie-kootchie out there - that some day they can make sense of all of that, pls send $$$B.

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Re: Physics Thread.

Postby A_Gupta » 20 Feb 2016 08:55

UlanBatori wrote:But it has a highly asymmetric mass distribution; i.e., density asymmetry. So each time the denser side came to face the Earth, gravity was much stronger than when the other side faced. So eventually that resulted in the spin stopping, which is why we don't see the far side of the Moon unless we go there.


Nothing to do with mass distribution.
https://en.wikipedia.org/wiki/Tidal_locking

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Re: Physics Thread.

Postby Raja Bose » 20 Feb 2016 09:01

Ah the hand waving (did I say wave? :eek: ) is in phultu flow....narayan narayan.....

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Re: Physics Thread.

Postby A_Gupta » 20 Feb 2016 09:24

ThiruV wrote:
UlanBatori wrote:So basically all they know is that SOMETHING emitted a signal rising in frequency and amplitude for a short time, amidst a lot of noise. The something was powerful enough to shake the sensitive beams at the LIGO facilities.


The paper claims they know a whole lot more, including where and what happened...don't get it, how did even know which direction the waves came from with just 2 LIGO detectors and what exactly happened? Brain too small to understand this magic obviously. if the gravitational waves are inert for the most part, the source could have been on the other side of the planet and done the job just as well.


1. Like with your two ears, you can somewhat localize where a sound came from, and likewise 2 LIGO detectors can.

2. There was a 7 millisecond interval between the two detectors - the wave traveled at the speed of light, ruling out any acoustic source. The amplitudes detected at the detectors were the same. A nearby source with a 1/r fall-off in wave amplitude and obviously at different distances (0.007 light seconds worth of distance) would not produce equal amplitudes.

Suppose the amplitudes at the two detectors differ by exactly 1% with no noise; the 1/r fall-off then implies that the distance of the source has to be a 100 times the distance between the two detectors; 0.7 light seconds is approximately halfway to the moon.

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Re: Physics Thread.

Postby member_29325 » 20 Feb 2016 10:29

A_Gupta wrote:1. Like with your two ears, you can somewhat localize where a sound came from, and likewise 2 LIGO detectors can.


2. There was a 7 millisecond interval between the two detectors - the wave traveled at the speed of light, ruling out any acoustic source. The amplitudes detected at the detectors were the same. A nearby source with a 1/r fall-off in wave amplitude and obviously at different distances (0.007 light seconds worth of distance) would not produce equal amplitudes.

Suppose the amplitudes at the two detectors differ by exactly 1% with no noise; the 1/r fall-off then implies that the distance of the source has to be a 100 times the distance between the two detectors; 0.7 light seconds is approximately halfway to the moon.


The two detectors are on a curve (earth surface), and they will encounter the max amplitude of the wave some delta(t) apart, but in 3D space, solving the equations for the source of the disturbance should yield best case, a closed curve in 3D-space that contains the source of the disturbance. So how did they know which point on that curve was the actual solution, to make the claims? I can accept that the math works out for such and such configuration of black hole masses, which would result in the gravitational wave that was seen, and so they believe that to be source of this wave. The 0.4 sec delay between this event and the gamma ray seems to be unexplainable by any known theory, so there seems to be new information that does not fit existing theories. This one point makes me wonder how much of existing theories actually fit in with these recent observations. Lots of sleepless nights for physicists no doubt...

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Re: Physics Thread.

Postby member_22733 » 20 Feb 2016 12:36

Amber G, thx for the info. It was enlightening.

UBji,

A vortex in a pressure field is not the same as a vortex in space time. A vortex in a pressure field does not change the co-ordinate system, i.e. it does not need the coordinate system itself to vary in response to changes in the pressure distribution.

A spacetime vortex instead warps the co-ordinate system around it. There is no way you can describe the phenomena independent of the coordinate system and you need a metric along with a bunch of mathematical objects (such as christofel symbols and the covariant contravariant co-ordinate independent tensor representation to describe what is actually happening). Which is why its so difficult (for me) to understand and EkPhathar was a genius to have figured it out all by himself.

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Re: Physics Thread.

Postby Amber G. » 20 Feb 2016 13:38

ThiruV wrote:
A_Gupta wrote:1. Like with your two ears, you can somewhat localize where a sound came from, and likewise 2 LIGO detectors can.


2. There was a 7 millisecond interval between the two detectors - the wave traveled at the speed of light, ruling out any acoustic source. The amplitudes detected at the detectors were the same. A nearby source with a 1/r fall-off in wave amplitude and obviously at different distances (0.007 light seconds worth of distance) would not produce equal amplitudes.

Suppose the amplitudes at the two detectors differ by exactly 1% with no noise; the 1/r fall-off then implies that the distance of the source has to be a 100 times the distance between the two detectors; 0.7 light seconds is approximately halfway to the moon.


The two detectors are on a curve (earth surface), and they will encounter the max amplitude of the wave some delta(t) apart, but in 3D space, solving the equations for the source of the disturbance should yield best case, a closed curve in 3D-space that contains the source of the disturbance. So how did they know which point on that curve was the actual solution, to make the claims? I can accept that the math works out for such and such configuration of black hole masses, which would result in the gravitational wave that was seen, and so they believe that to be source of this wave. The 0.4 sec delay between this event and the gamma ray seems to be unexplainable by any known theory, so there seems to be new information that does not fit existing theories. This one point makes me wonder how much of existing theories actually fit in with these recent observations. Lots of sleepless nights for physicists no doubt...


A_Gupta has explained pretty well, let me quickly add:
So how did they know which point on that curve was the actual solution, to make the claims?

- Read the paper, it is explained extremely well. (If you do not have good background in math, (as it seems to me that you do not ( no disrespect , see note #1 below), just use some one who has good math background (say a Math/physics college professor) to go over the basic part).

It is not some "guess" or "likely candidate" but they are virtually sure (sigma > 5). Trust me, there are perhaps millions of people here with good back ground in math who have seen and checked these mathematical steps, and if even a SLIGHT error or unclarity noticed they would have retracted the paper by now.

The 0.4 sec delay between this event and the gamma ray seems to be unexplainable by any known theory,


Again even a slightest discrepancy here --- if the data is not explainable or fit with the known theory -- will kill the paper. (Hint: There is ALWAYS some delay between gamma ray or any EM radiations . this is why one sees rainbows.... EM waves (as opposed to gravitational waves) gets delayed if it passes through earth's atmosphere, or water (slower still), or glass (even slower), burqua (stopped for ever)..
The delays due to neutron stars etc are pretty well calculable.

Let me just add a trivia here. Which will send madarasa mathwala in a tizzy but ask any physics professor or do your own calculations . . Do you know how long does it take for a photon from the center of our own sun to reach us on the earth..?

The answer is about 4000 years!

(it takes about 4000 years for it to reach from the center to the surface of the sun, and about 8 minutes afterwards. Graviton (irrespective of where it started) will reach in about 8 minutes.

(So time delay between gamma ray burst and gravitational delay is normal - it depends where the photon started and medium it went through. BTW this is one of the reason the we are more excited that we will get new insight about pulsars, supernova etc..)

Point is one has to know some basic physics before one can understand the basic part and then ask the questions.

Hope it helps.

Note1 - No disrespect but the reason I doubt you do not have necessary background even in the most basic aspect is, just to show one example, your this post. (https://forums.bharat-rakshak.com/viewtopic.php?p=1981860#p1981860 Do you now see why?

If not, see my next post for details -- if interested.

I do hope, at least for some this has been helpful.

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Re: Physics Thread.

Postby UlanBatori » 20 Feb 2016 16:39

A_Gupta wrote:
UlanBatori wrote:But it has a highly asymmetric mass distribution; i.e., density asymmetry. So each time the denser side came to face the Earth, gravity was much stronger than when the other side faced. So eventually that resulted in the spin stopping, which is why we don't see the far side of the Moon unless we go there.


Nothing to do with mass distribution.
https://en.wikipedia.org/wiki/Tidal_locking

Ah! A classic case of dismissive non-pompously-arrogant Physics paper-parroting with technobabble in lieu of the sane, E-Z-2-samajh explanations that are a trademark of UBCN: If you read under your link, you might have found this:
Q and k_2 are generally very poorly known except for the Moon, which has k_2/Q=0.0011.
Reading on, we see that it is "tidal distortion", IOW, the tide pulls the surface of the Moon down towards it. Works for rubber balls, but the Moon is a bit rigid. Or something else that causes a slowdown in every rotation.

What the Authority I mentioned, mentioned, was that they used all these sophisticated pissikobabble in lengthy Simulations lasting many years, and found that eventually it locked the Moon with the denser side (call it the Physicist Side because of the sheer Weightiness of it) facing the Earth. Have you found some evidence that it is the non-dense aka YakDung-head side that faces the Earth?
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