Physics Discussion Thread

sanjaykumar · Post by **sanjaykumar** » 16 Feb 2016 02:49

Poul Anderson wrote a story/novella posited on transistor (silicon circuits) life forms with descriptions of ecosystems.

What you describe TSJ is convergent evolution-it is reasonable to expect life forms on Earth-like planets to show bifold symmetry and be bipedal and have digits at the end of limbs (and answer to the name of Bob).

member_29325 · Post by **member_29325** » 16 Feb 2016 03:16

UBsaar, first let us see how they come up with gaand unified theory in EM....I am sure many billions of $s worth of research grants will be handed out for all that now. A lot easier and more lucrative than doing a heist on the corner store potti-kadai for cash. If you really want to get a lot of free money, write a research grant proposal in the hottest buzz-word laden field in any given area, they said.

Hitesh · Post by **Hitesh** » 16 Feb 2016 03:32

UlanBatori wrote:
If this humongous event occurred, and as I hear it, "emitted more energy in a minute than there is light in all the Universe" , AND this wave travelled towards the LIGO Lab at the speed of light, why has **NOTHING** of it being observed in any other part of the spectrum? No supernova flash, no spinning, flashing quasar/pulsar/Stellar MASER/cosmic flash, no radio waves. They should have reached at the SAME TIME!!

Something smell fishy?

Sounds like more "Martian Meterorites" and "Water on The Moon" and "Life on Mars" budget-time hallucinations.

Don't forget the effect of gravitational lensing. The light has to travel through matter or around matter and may be disturbed by the gravitational forces. However, the gravitational waves travel unperturbed (so as they claim). Hence we may be able to see the gravitational waves first then the light and EM spectrum that comes with it. That is why gravitational waves are now being hailed as a great precursor to finding and localizing where we can expect to witness supernovas and other big bang item events in advance.

*Added later- from Wiki: https://en.wikipedia.org/wiki/First_obs ... in_the_sky

Location in the sky

Gravitational wave instruments are whole-sky monitors with little ability to spatially resolve signals. A network of instruments is needed to locate the source on the sky through triangulation. With only the two LIGO instruments in observational mode, GW150914's source location could only be confined to an arc on the sky. This was done via analysis of the 6.9+0.5
−0.4 ms time-delay, along with amplitude and phase consistency across both detectors. This analysis produced a credible region of 140 deg2 (50% probability) or 590 deg2 (90% probability) located mainly in the Southern Celestial Hemisphere.[29]

The third LIGO was down and undergoing upgrade and maintenance so it was not possible to triangulate the source.

UlanBatori · Post by **UlanBatori** » 16 Feb 2016 04:08

The third LIGO was down and undergoing upgrade and maintenance so it was not possible to triangulate the source.

Ooooo!!!! Sure sign of hanky-panky. Sounds like Nawaz Sharif's excuse for not arresting Haffez Saeed.
Southern Celestial whatzit - or an iceberg butting into the shoreline in Antarctica. Or an earthquake in Tasmania.

TSJones · Post by **TSJones** » 16 Feb 2016 05:05

as your loyal and humble, ill informed church (temple) mouse, I would timidly point out to this august assemblage that objects in the universe that are very far away from us can have their EM spectrum blocked or absorbed by clouds of dust, and other astronomical events and structures, etc.

and sometimes our present day telescopes regardless of spectrum, just flat ain't got the horses to get 'er done.....

just sayin.......

Amber G. · Post by **Amber G.** » 16 Feb 2016 06:01

ThiruV wrote:... first let us see how they come up with grand unified theory in EM....I am sure many billions of $s worth of research grants will be handed out for all that now.

I don't know who are your "they" but this experiment does not have much to with grand unified theory or other such things...

1. The theory is 1916 - Einstein theory which NO ONE, except Jinn thermodynamics types, doubts now or doubted for decades. It is not a new fancy theory but just use of extremely sensitive piece of equipment which observed the gravitational waves directly..It is silly, IMO, to go off topic here, and talk about things like: .

A lot easier and more lucrative than doing a heist on the corner store potti-kadai for cash. If you really want to get a lot of free money, write a research grant proposal in the hottest buzz-word laden field in any given area, they said.

Excuse me, but won't it be more practical if you try to take advantage of this lucrative stuff it if you think this is lot easier than doing a heist...

Just saying ...
****
Just a request - can we move obvious off-topic chit chat and usual rona - dhona in some other dhaga please.

member_29325 · Post by **member_29325** » 16 Feb 2016 06:06

AmberG wrote: Excuse me, but won't it be more practical if you try to take advantage of this lucrative stuff it if you think this is lot easier than doing a heist...

That's called humour, you may have heard of it. No need get all sensitive. Yeah, just pointing there will a thundering herd of research grants because of this discovery. that is all. But Indian physics needs to be more practical and useful given the limited budget for science R&D -- so I am not sure spending tons of money on cutting-edge fields is the need of the hour, more than creating an army of science professionals who create things...but all OT and hence EOD.

Amber G. · Post by **Amber G.** » 16 Feb 2016 06:25

^^^ My comment about OT and sentence after "***" was not directed towards you. .. and BTW you may like to take your own advice about "No need to get all sensitive"..Humor can cut both ways (if you think you were just joking, my quote which you quoted could have been made in jest too .

)

member_29325 · Post by **member_29325** » 16 Feb 2016 06:45

Ok, so looking at all the nice videos of two stars circling each other and emitting gravity waves, it seems odd that they got this one odd blip, and attributed it to a cataclysmic two-star event. If these waves are continuously generated when two stars spiral into each other, shouldn't the LIGO people be able to detect pulses from the stars, rather than one short blip that everyone is celebrating? Does this mean LIGO is going to periodically announce results, or is the circus over for now? Can't they detect some other binary system that will be giving out similar gravity waves?

UlanBatori · Post by **UlanBatori** » 16 Feb 2016 07:36

is the circus over for now? Can't they detect some other binary system that will be giving out similar gravity waves?

NSF funding cycle deadlines are Feb 1 and ~ July something. So next major "discovery" will be around June-July onlee.

member_29325 · Post by **member_29325** » 16 Feb 2016 07:59

UlanBatori wrote: NSF funding cycle deadlines are Feb 1 and ~ July something. So next major "discovery" will be around June-July onlee.

Don't we all love science.

TSJones · Post by **TSJones** » 16 Feb 2016 08:42

first, if I am able to understand it correctly, they must create a model of what they are looking for and it must must be agreed to by the various represented entities. the model must conform to the theory of relativity(of course) and be of special scientific interest that astrophysicists and astronomers are dying to know about. Again, it too will be an interesting calculation

once they have established what they are looking for then they must make sure their instruments can sense it so they will create false positive events to test their instruments. once they are satisfied their LIGO equipment are working correctly, the search is on....

just my opinion and I can be very wrong about it..........

Hitesh · Post by **Hitesh** » 16 Feb 2016 11:23

UlanBatori wrote:
The third LIGO was down and undergoing upgrade and maintenance so it was not possible to triangulate the source.
Ooooo!!!! Sure sign of hanky-panky. Sounds like Nawaz Sharif's excuse for not arresting Haffez Saeed.
Southern Celestial whatzit - or an iceberg butting into the shoreline in Antarctica. Or an earthquake in Tasmania.

It was pure luck that they got it so soon and they were not expecting to get any signal of the sort when they underwent the planned downtime and maintenance. Anyway, given your flippant remarks and condescending attitude, I think I will refrain from responding to any of your posts.

member_29325 · Post by **member_29325** » 16 Feb 2016 20:10

If all of this drama is with 2 LIGO detectors online, then I am sure there will another event with all 3 ligo detectors online to triagulate the source of the noise. UB's point still remains that all this excitement of a detected gravity wave that may or may not have originated from the cosmic event that was advertised is still a question mark. Scienctific inquiry requires that the next experiment not only detect the wave but also triangulate it to the origin, multiple times....until then the jury is out.

UlanBatori · Post by **UlanBatori** » 16 Feb 2016 21:37

The Cold Fusion discovery was also announced with great certainty. And once announced, many around the world jumped on that bandwagon saying "ME TOO!!". DAWN OF A NEW AGE: Cold Fusion power plants would come up all over. No more energy crisis, no nuclear plants putting out radioactive garbage, no nuclear weapons. No poverty, limitless riches.... $80M in lab funding IMMEDIATELY put into U. Utah.

Then it went cold and the 'researchers' disappeared. The "ME TOO" jerks are still around, hardly learned anything from the experience. Last heard, about 15 saal pehle, they had "discovered" hydrogen-powered buses (like they have in Iceland).

Checking into the NSF deadlines, NASA budget hearing dates etc is just part of "doo dill-e-jantz" learned the hard way - by staying awake. It may appear middle-finger-flippant but it's a good reliable predictor of 99% of these overhyped announcements.

So - let's see. Say I wanted to play a practical joke on these ppl. I know 1 of their 3 sensors is kaput. So I just send someone to do a WHUMP-THUMP on the roof of both labs at a highly synchronized instant - 0.4ms apart. And turn on the TV in a few hours with popcorn all ready and floor cleaned for

Maybe whatzername is coming up for tenure or promotion to full prof or NAS membership. Oh, when is the No-Bill Pissiks Prize nomination deadline?

member_29325 · Post by **member_29325** » 16 Feb 2016 22:05

Apparently, they tested fake signals in a double-blinded manner to ensure that the LIGO could not be manipulated, so it may not be a total fraud like cold fusion, which was completely unrepeatable anywhere in any lab other than the guys who proclaimed they had it done. There has to be that kind of backup verification here too, in order to for skeptics to consider this is all real, but building these LIGOs are enormously expensive it appears. Who's going to be building a second LIGO (x3) to double-check results from this LIGO triad?

member_27581 · Post by **member_27581** » 16 Feb 2016 22:29

UlanBatori wrote:If this humongous event occurred, and as I hear it, "emitted more energy in a minute than there is light in all the Universe" , AND this wave travelled towards the LIGO Lab at the speed of light, why has **NOTHING** of it being observed in any other part of the spectrum? No supernova flash, no spinning, flashing quasar/pulsar/Stellar MASER/cosmic flash, no radio waves. They should have reached at the SAME TIME!!

I was wondering where is Genghis khan for long.

That's a very profound question. One possible explanation i can think of that they didnt emit energy in other spectrum was that this was a stellar mass BBH pair. These pairs are not expected to have matter around them. Read that there could be a GRB coinciding with the event which was detected very close to this discovery although the location is not precise (as is the case with GRB generally). BTW that GRB was in Hard XRay spectrum.
Ducking for cover...

member_27581 · Post by **member_27581** » 16 Feb 2016 22:44

ramana wrote:AmberG, Can you elaborate on how it could start a new era?

I think Amber G has provided a great explanation. So I will use a simple analogy and am taking a slightly different line with a bit of speculation.

1. Analogy: I would think of it as being able to "see" in infrared. We may be able to see rare pheonomena e.g. black hole mergers/collisions, where most of energy is expected in Gravitational wavs.
2. Apart from the ability to observe in a different "spectrum" (yes it is wrong because it's a different wave altogether), what gravitational waves offer us is the potential ability to "see" dark matter which is a very pressing matter as we know that the known matter/energy constitutes only 5% of observable universe, with dark matter comprising ~38%. Dark matter interacts with other matter only gravitationally, forming the "scaffolding" of around which galactic super clusters are formed.
3. Added later, Using EM waves we will be able to look closer to big bang, before first light came

member_27581 · Post by **member_27581** » 16 Feb 2016 22:49

Amber G, one question that I have is that are these waves also going to have impact on time part. So far I see only space part being talked about.

UlanBatori · Post by **UlanBatori** » 16 Feb 2016 23:41

Who's going to be building a second LIGO (x3) to double-check results from this LIGO triad?

NaMO, of course! In one of those 400,000 villages that don't have any extraneous lighting to disturb the sky because they don't have no electricity.

In fact, more LIGO labs ARE needed. They should outsource the detector technology to Beijing, so that 10,000 such detectors can be placed all over the Earth and some in Space. BECAUSE, unlike telescopes, this thing can sense the same regardless of which side of the Earth it is, hain? So like tomography, more sensors, more certainty and accuracy.

Getting back to the question of other parts of the spectrum, thanks ranjanji. If there was any matter in the vicinity, it would have been tandoor because of this burst, and so would have emitted. This means dust clouds, stars, stray planets, maybe even Dark Matter. So now we face a prospect that there are these complete Black Holes that have totally eaten up **ALL** mass in the vicinity, and are zooming around near speed of light, **COMPLETELY** undetectable except by gravitation, and that not too well because they move as fast as their own gravitational waves?

Think of the movie rights to THAT scenario! Only detectable if and only if they encounter other matter, in which case there will be a swift and one-sided blaze. So!!! All that Dark Matter may in fact be inside these things, and be completely gone from detection??? They may be all around us, silent muggers?

Perhaps coming to a solar system near u!! At the speed of light!!

Amber G. · Post by **Amber G.** » 17 Feb 2016 00:00

UlanBatori wrote: blaha blaha ..The Cold Fusion blah ..blah ..Hafeez saeed ..blah blah 2002 Guj(a)rat .. blah blah ..."doo dill-e-jantz" jerks" blah..blah .."when is the No-Bill Pissiks Prize nomination deadline?"...RAW/CIA/MIT/CALTECH conspiracy ... blah blah..

Few of the principals in LIGO already have a Noble ..some are indeed great like Einstein (theory) and a few are quite famous even without a Noble.. But..

UB, PLEASE cut it out, and stop embarrassing your self. As you know I have respect for you and your initiative to counter those "scholars" arguments when NaMo was visiting SV, but sadly now, to me your arguments sound more like those scholar's posts -- (although your pinglish is more fun

) -- with your ridiculous innuendo's and endless off-topic, irrelevant associations.

I mean there ARE a few things like moon landing which may NOT be a conspiracy even if one keeps repeating "cold fusion".. (No serious scientist fell for that BTW, more of this later). 26/11 did happen no matter how suspicious some say it is. Telescopes did discover other satellites.. ityadi ityadi..

For crying out loud, did you even read the post(s) I posted, or read the paper I posted as pdf? Of course there are many other sources which could answer all the points you seem to have raised here.. and more. More importantly please do THINK because some of the answers are quite easy if you use math or logic, and you do have a background to understand that.

All - Let me state a few obvious points. I will respond if there are genuine physics related followup but , obviously, I will ignore silly off-topic posts.

-- Actually the discovery of gravitational waves is icing on the cake, the amazing part is LIGO engineering. IOW Even without the discovery of gravitational waves, the LIGO is amazing and a BIG DEAL. It is the most precise device. EVER.. 1 part is 10^21 is something like million (or billion) times better than anything in the past. Remember those Michelson Interferometers -- one of the most amazing experiments I fondly remember. LIGO is several order of magnitudes more sensitive. The design principles can be understood (and checked) by ordinary Graduate students and the calibration has been checked. (This is 40 years in making ..People like Weiss, Thorne and Drever (profs with high respect and credibility) and not to mention THOUSANDS others have taken part -- the paper has 1004 co-authors!!)..

-- Another notable part is software/routines used to analyze / band-pass filtering of big data, so one can statistically detect even a small signal among large noise.

So - let's see. Say I wanted to play a practical joke on these ppl. I know 1 of their 3 sensors is kaput. So I just send someone to do a WHUMP-THUMP on the roof of both labs at a highly synchronized instant - 0.4ms apart. And turn on the TV in a few hours with popcorn all ready and floor cleaned for

Do you even realize how Zaid Hamidish you (UBji) sound when you post type of questions you posted above

). .. but this below takes the cake.. no exaggeration even ZH will not be that creative in ignoring facts and repeating "WHY WHY WHY.."

why has **NOTHING** of it being observed in any other part of the spectrum? No supernova flash, no spinning, flashing quasar/pulsar/Stellar MASER/cosmic flash, no radio waves. They should have reached at the SAME TIME!!

"NOTHING".. Can you list A SINGLE event which ought to be there and was NOT observed by other independent sources. (Of course one would NOT observe any supernova flash, or flashing pulsar if the event considered was two black-holes). What exactly you are talking about when you say "They should have reached at the SAME TIME!!"
Please be specific.

Dear UB, just read the paper, or do your own checking.. Every SMALL detail has been checked, re-checked and re-rechecked. .. The experiment data is consistent, to the best of their efforts, with EVERY other expected measurement done for this event by other means.

I hope this helps.

Vayutuvan · Post by **Vayutuvan** » 17 Feb 2016 00:07

sanjaykumar wrote:Poul Anderson wrote a story/novella posited on transistor (silicon circuits) life forms with descriptions of ecosystems.

Do you remember the name, by any chance?

By the way a small tidbit re. Robert Forward from Wikipedia page on LIGO

Robert Forward operated an interferometric detector at Hughes in the early 1970s.[17]

Amber G. · Post by **Amber G.** » 17 Feb 2016 00:08

Space part (eLISA), from what i know is still far away. Some thing like 2030. I may be wrong though as it may come sooner (or later). Lisa path finder part (preliminary part) was launched into space about a month or so ago.

Vayutuvan · Post by **Vayutuvan** » 17 Feb 2016 00:11

Amber G. wrote:Interesting tidbit - when EM waves were directly discovered by Hertz (in late 19th century)
...
Asked about the ramifications of his discoveries, Hertz replied,
"Nothing, I guess."

AmberG: Will the human race survive or it will end after fossil fuels are exhausted and/or Global warming takes its toll? 100 years is a very long time what with the efficiency with which we are able to exploit the resources (mostly non-renewables - He, Al, Li in coming years and of course fossil fuels).

Amber G. · Post by **Amber G.** » 17 Feb 2016 01:00

UlanBatori wrote:The Cold Fusion discovery was also announced with great certainty. And once announced, many around the world jumped on that bandwagon saying "ME TOO!!".

I remember the event very well so let me tell a personal story which may give some perspective..
When the discovery was "announced", not through a paper, but via a press conference by university's (Utah U) big shots, I tired to read the original paper, but it was not out.

My neighbor, a chemistry professor, sort of teased me, because the discovery was made by a Chemist. There was lot of hulla-gulla but little scientific detail came out. There was little e-mailing in those days and I can not get my hand on any pre-print etc. Within day or so, somebody who knew somebody, got a copy of the paper from somebody (Utah U, and the by now famous professor were very secretive) faxed the paper to my office.

Even thoughI was not in the field, my immediate reaction was, -- "this looks very sloppy". Same or similar reaction by others who had better background. I remember telling at that time to a local ddm-reporter, specifying 98% probability

) that this does not look right and will be proven so when checked.

Not everyone was jumping in to wagon, many simply could not reproduce the result but as we both know Georgia Tech (or one group from here) was one of the "ME TOO" who made a fool of themselves by saying the "we too see the cold fusion". IIRC this group retracted the paper with in one or two days, after others pointed out the error. So in truth, not everyone went "ME TOO" but just one group from Georgia Tech, and that too for only 2 days before they changed their mind.

But I am sure, you know that very well. (If not just check out the newspapers around April (?) 1989

Added later:

... $80M in lab funding IMMEDIATELY put into U. Utah.

Then it went cold and the 'researchers' disappeared. The "ME TOO" jerks are still around, hardly learned anything from the experience. Last heard, about 15 saal pehle, they had "discovered" hydrogen-powered buses (like they have in Iceland).

I believe Utah professors were thoroughly discredited, their career ruined, Georgia tech group was humiliated (they withdrew the paper with in days etc). This "hardly learned anything" kind of narrative is simply false, if not dishonest.

Amber G. · Post by **Amber G.** » 17 Feb 2016 04:02

Looks like I am not the only one who thinks that ..
Hawking: Gravitational Waves Could Revolutionize Astronomy

You may see the whole BBC interview etc..
https://www.youtube.com/watch?v=PlNghMbHVUE

Amber G. · Post by **Amber G.** » 17 Feb 2016 04:49

Amber G. wrote:Space part (eLISA), from what i know is still far away. Some thing like 2030. I may be wrong though as it may come sooner (or later). Lisa path finder part (preliminary part) was launched into space about a month or so ago.

More here: The Next Big Gravitational Waves Experiment Is Now Getting Started in Space

sanjaykumar · Post by **sanjaykumar** » 17 Feb 2016 05:03

^^ Sorry I can't recall the name of the Poul Anderson story.

With respect to the comments about the perennial question of why the night sky is not as bright as day, a corollary could be why does LIGO detect any discrete signal? In an infinite uiverse following the Cosmological Principle, there are an infinite number of cataclysmic events occcurring. So we arbitrarily postulate an isotropy in an artibrary locality to get around this.

But there must be bigger cataclysmic events in the volume of space further out. Or perhaps the Universe is not old enough to see a cosmic gravitational wave background as with the thermodymanics of the primordial fireball. Which brings us to the question, is there a bigbang remant of gravitational waves?

member_29325 · Post by **member_29325** » 17 Feb 2016 05:18

Must be a bear to build a LIGO like device in space like eLISA. But technology has advanced enough that maybe it will be easier to do remote repairs on eLISA using miniscule robots that can do little odd jobs on their own. should be interesting. Can easily imagine some part getting misaligned due to some space debris whack it or some such mishap.

UlanBatori · Post by **UlanBatori** » 17 Feb 2016 06:18

I can well believe that the instrument is hyper-sensitive, after all it was designed by physicists.

Imagine what poor Galileo must have gone through, going to Physics meetings where the Flat Earth Revolutionaries (oops! oxymoron!) met, and asking the odd question like "what is beyond ur horizon?" Immediate personal attacks, tar, feathers, lynchmobs...

All I can say is this: I remember presenting some paper on the Nonintrusive Measurement of Rate of Cooling of Yak Dung, and saying:" I am not sure why this result came out this way...".
The Head of the DungMechanics Division of the Khan's Fauj was sitting in the front row with a grin from ear to ear:

UB, Could it be Cold Fusion, perhaps?

But then he was not a pissikist, nor was I, so it was all in good jest. No problem at all, he just signed off on my next proposal for 300,000 yak-dung chips.

UlanBatori · Post by **UlanBatori** » 17 Feb 2016 07:06

This is scary. Sounds like two Black Holes hiccupping after a few Rooh Afzas too many

Ultimately named Gee-Dubya 150914

Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.

Amber G. · Post by **Amber G.** » 17 Feb 2016 07:06

UlanBatori wrote: ...
All I can say is this: I remember presenting some paper on the Nonintrusive Measurement of Rate of Cooling of Yak Dung, and saying:" I am not sure why this result came out this way...".
The Head of the DungMechanics Division of the Khan's Fauj was sitting in the front row with a grin from ear to ear:
UB, Could it be Cold Fusion, perhaps?
But then he was not a pissikist, nor was I, so it was all in good jest. No problem at all, he just signed off on my next proposal for 300,000 yak-dung chips.

Good for you sir! A convivial person like me would have said something like..

यत्र दादुर वक्ता, तत्र मौनं हि शोभनम्

UlanBatori · Post by **UlanBatori** » 17 Feb 2016 07:20

They must have paid big $$ to generate a sound track so purely evil that I cannot go to sleep after listening to it.

So this is the thing I cannot comprehend, among many other things. Even at speed of light, are the Black Holes so small in extent that an "interaction" is over inside a "blip"? Should it not have taken a lot longer for each interaction? OK, half a second is 90,000 miles...
How big is the diameter of the event horizon of a Black Hole?

sanjaykumar · Post by **sanjaykumar** » 17 Feb 2016 07:58

Oh yes Fred Hoyle wrote The Black Cloud, haven't read it but he argued for panspermia with Wickersinghe.

TSJones · Post by **TSJones** » 17 Feb 2016 09:43

depending on the mass, a black hole event horizon can be the size of a solar system or maybe even larger.

but what is an event horizon? it is a point where nothing can escape a black hole's gravity.

so my question is at what point is the ripple that was observed generated?

when the event horizons clashed or when the singularities became one? how romantic!

TSJones · Post by **TSJones** » 17 Feb 2016 10:09

ranjan.rao wrote:Amber G, one question that I have is that are these waves also going to have impact on time part. So far I see only space part being talked about.

not sure I understand your question.

can space and time be separated?

Please allow me to disassemble for a bit:

my poor understanding of relativity is that space time depends upon the speed and/or gravity that the observer is subject to.

to wit, the faster the observer is going the more time slows down

the general theory states that gravity functions in the same manner. the greater the gravity the more time slows down.

but please note that space is also affected.

the faster the observer travels, the shorter the physical distance.

same with gravity, the more gravity, the shorter the physical distance.

that is to say, an observer at a black hole, the physical distance to a nearby galaxy is not near as far as to observer on a rocky planet orbiting a medium size star.

so space time is a variable depending on the conditions the observer is being subjected to.

that is , the universe physically changes depending on the observer's speed and/or gravity. you can't separate space time.

therefore, we here on earth are observing the ripple at our speed and gravity, which prolly makes the ripple seem to us as really, really quick.

I am prolly wrong about all this, oh well......just thought I would take a stab at it......

Amber G. · Post by **Amber G.** » 17 Feb 2016 11:33

TSJones wrote:depending on the mass, a black hole event horizon can be the size of a solar system or maybe even larger.

The black holes varies in size - from micro (less than a mm) to super (billions of Km).. and the mass depends on the size.
Please see this post from 2009 in this dhaga: viewtopic.php?p=594446#p594446

"Bol bol bol... ..
Mister Gol Matol
Just how massive is a big black hole?

Half the radius
Divide by G
and Multiply by the
square of C ...."

BTW, don't get distracted too much by the "black hole" part, any solar type system (even earth-sun system) will produce the gravitational waves. The even noted was measurable because the bodies were massive (30x solar mass) and moving rapidly (half the speed of light)... so to answer your question (please see the PRL paper for details):

so my question is at what point is the ripple that was observed generated?

When the two black holes were orbiting each other - spiraling down to merge, each with the velocity of about 0.6 c..

Amber G. · Post by **Amber G.** » 17 Feb 2016 11:49

Speaking of black holes, lost in other exciting news this part of LIGO is also a very exciting.

LIGO’s discovery is also the only direct evidence we have for the existence of any black holes.

(Astronomers had previously obtained only indirect evidence in the form of X-rays from matter falling into other black holes and the distortion of the orbits of stars at galactic centers that host supermassive black holes)

Moreover latest papers are also discussing and noting that the stellar-mass black holes that merged in this observed event are themselves surprising. Astronomers previously thought that such stellar-mass binaries would either not form at all or, if they did, they would be too far apart to merge within the age of the universe. LIGO’s detection has showed that this is untrue, prompting what many think another major new understanding in astronomy.

Amber G. · Post by **Amber G.** » 17 Feb 2016 12:29

Responding to Ulanbatori's post Hitesh wrote: It was pure luck that they got it so soon and they were not expecting to get any signal of the sort when they underwent the planned downtime and maintenance. Anyway, given your flippant remarks and condescending attitude, I think I will refrain from responding to any of your posts.

Refraining from responding to flippant remarks and condescending attitude is a good idea.

Yes. In fact, they say that when the event was observed the system was in "test" mode, and yet to be switched to full production mode. The event was observed last September. There were quite some rumors (even brf had posts about that) but they waited to check everything before announcing.

Also, there were more events, which they are looking, some may be noise, but one in particular (LVT151012) is an interesting candidate event, the data for it less statistically significant (about 2σ). Per published reports they are going to analyze it further but the signal, which was detected last October, was similar to this even and was “clean and clear”.

UlanBatori · Post by **UlanBatori** » 17 Feb 2016 17:19

When the two black holes were orbiting each other - spiraling down to merge, each with the velocity of about 0.6 c..

Which raises the obvious question (surely answered in those 1004-author papers, but I have no intention of trying to read it, way over my head!):

Why not before and why not after? Was it all over in a second after that? Surely someone has thought about it. I mean, this should have got worse and worse until kaboom! the big gravitational shock wave was generated at trans-optic Drag Divergence Lorentz Number or whatever? It's been over a year and that hasn't yet wiped us out, so what happened? They broke up and flew apart?