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#4385148 - 10/15/17 11:31 PM Gravitational waves - who knows about these?  
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I was reading about the fellows who won the Nobel prize for there detection. Very cool. But it was mentioned in an article that these waves carry information about their origin.
I can't grok that and need someone to explain... The analogy I think of is a pond when it rains. Ripples comes from the rain drops. Standing at one point in the pond - how would you know which ripple is apart from what?

Great website from CalTech, but doesn't answer my question.
https://www.ligo.caltech.edu/page/what-are-gw

Anyone? I need to understand.

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#4385149 - 10/15/17 11:57 PM Re: Gravitational waves - who knows about these? [Re: piper]  
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gravity it seems travels much like waves across a body of water - idk if that's correct but that's what I heard - hope that answers your question

popcorn

here is a question for you - why do you need to understand it ? Are you taking a physics course or something maybe


"everything lives by a law, a central balance sustains all"
#4385150 - 10/16/17 12:01 AM Re: Gravitational waves - who knows about these? [Re: piper]  
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The Polynesians are said to be able to 'read' waves and can tell what direction land is.


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The Fw190A could not fly with the outer cannon removed.
There was no Fw190A-8s flying with the JGs in 1945.
#4385152 - 10/16/17 12:09 AM Re: Gravitational waves - who knows about these? [Re: piper]  
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Yes, a pond in a rain fall can have unlimited ripples but which gravity waves we're recording are from events we are witnessing. We can't recall the density, shape or chemistry of each raindrop but we can see, hear and witness a 1970's Buick splashing in the pond from a considerable height and record the wave data emanating from that.

#4385155 - 10/16/17 12:17 AM Re: Gravitational waves - who knows about these? [Re: piper]  
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what if more then 1 Buick hit the pond ?


"everything lives by a law, a central balance sustains all"
#4385159 - 10/16/17 01:41 AM Re: Gravitational waves - who knows about these? [Re: piper]  
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These are three-dimensional "ripples" in space-time itself and as I understand it are constantly being generated by imploding stars, quasars, colliding galaxies, supernovas etc.


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#4385161 - 10/16/17 01:46 AM Re: Gravitational waves - who knows about these? [Re: piper]  
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thank you now it all makes more sense


"everything lives by a law, a central balance sustains all"
#4385167 - 10/16/17 01:59 AM Re: Gravitational waves - who knows about these? [Re: Haggart]  
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Originally Posted by Haggart


here is a question for you - why do you need to understand it ? Are you taking a physics course or something maybe


I'm a very curious person and astrophysics interests me. I don't have the math background to analyze their findings so I ask.

#4385171 - 10/16/17 02:09 AM Re: Gravitational waves - who knows about these? [Re: piper]  
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don't know much more about this than what i've read on-line but i did get to see the supercomputer that does all of the LIGO calculations, it's in Milwaukee at UWM

in short LIGO used an interferometer to verify the existence of gravity waves, which I would assume would also mean that gravity has a "speed" as well


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#4385172 - 10/16/17 02:10 AM Re: Gravitational waves - who knows about these? [Re: piper]  
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To measure gravitational waves, you need an apparatus of such incredible sensitivity, it's almost impossible to measure any but the biggest waves. Using your pond analogy, we don't have any instruments that can measure the waves of raindrops, but we do have an instrument that can measure the wave created by a boulder dropped into the pond. Likewise with LIGO, it can measure the gravitational waves created by the collision of two black holes. The information carried by that wave would include the mass, velocity, and direction of the black holes (think of how ordinary sound waves give you information about a car, say, heading toward you: you could roughly tell its velocity and direction based on the frequency or pitch of the sound waves it emits as it approaches. And if two cars collided near you, you would probably have a good idea of their relative masses based on the sound from the crash.)


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#4385174 - 10/16/17 02:14 AM Re: Gravitational waves - who knows about these? [Re: Clydewinder]  
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Originally Posted by Clydewinder
...which I would assume would also mean that gravity has a "speed" as well



Yes, the speed of light.


War is the continuation of natural selection by other means.
#4385178 - 10/16/17 02:30 AM Re: Gravitational waves - who knows about these? [Re: WolfDancer]  
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Originally Posted by WolfDancer
Originally Posted by Clydewinder
...which I would assume would also mean that gravity has a "speed" as well



Yes, the speed of light.


So if the sun was to disappear, it’d take 8 minutes for the Earth to go shooting out of the solar system?


Phil

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#4385179 - 10/16/17 02:37 AM Re: Gravitational waves - who knows about these? [Re: NH2112]  
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Originally Posted by NH2112
Originally Posted by WolfDancer
Originally Posted by Clydewinder
...which I would assume would also mean that gravity has a "speed" as well



Yes, the speed of light.


So if the sun was to disappear, it’d take 8 minutes for the Earth to go shooting out of the solar system?


Yes.

#4385194 - 10/16/17 03:49 AM Re: Gravitational waves - who knows about these? [Re: piper]  
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"Isaac Newton thought the influence of gravity was instantaneous, but Einstein assumed it travelled at the speed of light and built this into his 1915 general theory of relativity."


"everything lives by a law, a central balance sustains all"
#4385202 - 10/16/17 07:30 AM Re: Gravitational waves - who knows about these? [Re: piper]  
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A much more sensitive gravitational wave observatory, if we want to call it like that, has been proposed by ESA. Place three interferometer satellites at various lagrange points, and we could jack up the sensitivity by several orders of magnitude. As there would be three detectors the spatial direction could be improved a lot. That way we could detect much weaker gravitational waves, and better pinpoint the directions from which they are coming. This will open a new field of astronomy. Think of the LIGO detector as the first telescope used by Galileo Galilei pointed at Jupiter to discover that it had moons. Picture the improvements that electromagnetic wave astronomy has made since (optical, radio, infrared, X-ray), and then think of what gravity wave astronomy might reveal to us four or five hundred years in the future.
Unlike electromagnetic waves, gravity waves are not being dampened/absorbed other than by the stiffness of spacetime itself. Someone gave the analogy of LIGO being able to measure the waves that a boulder creates when thrown into a pond. Except, when the water in the pond is how light travels in space, for gravity waves the pond is filled with massive, cold steel. And we can measure the tiny shudder that the boulder makes. And the first event that LIGO detected was the equivalent of two really enormous boulders, so big that they had almost excluded it from the signals for which the computer would generate an alert because they didn't really expect to get a signal like that.
(In that collision of two black holes, more than 36 sun masses were radiated away just as gravity waves...
Gravity waves are, by the way, the reason why two objects can never orbit each other for all eternity. Every moment they are in motion, their gravitational interaction generates gravity waves, slowly eating away from their kinetic energy, forcing an ever tighter orbit; for most bodies the effect is so small that for all practical matters you wouldn't notice a difference. But black holes and neutron stars generate a LOT of gravity waves, so the effect is more pronounced.)


Notice that in the Interstellar movie, they visualized the spiral distortion of spacetime around the black hole (you can see it by the spiral distortion of the accretion ring, and the starfield in the backdrop); this is probably not so surprising as the visualization was supervised by a team of physicists under Kip Thorne, one of this year's nobel laureates.

#4385205 - 10/16/17 08:11 AM Re: Gravitational waves - who knows about these? [Re: Ssnake]  
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Originally Posted by Ssnake

Gravity waves are, by the way, the reason why two objects can never orbit each other for all eternity. Every moment they are in motion, their gravitational interaction generates gravity waves, slowly eating away from their kinetic energy, forcing an ever tighter orbit; for most bodies the effect is so small that for all practical matters you wouldn't notice a difference. But black holes and neutron stars generate a LOT of gravity waves, so the effect is more pronounced.)


But black holes and neutron stars also have a LOT of inertia, so that'd cancel that out. The effect still is there of course, but it's no different than a couple of small rogue planets orbiting each other in terms of the ratio of orbital inertia vs orbital decay via the creation of the gravity waves.

There is also the fact that space isn't totally empty. You do have atoms floating around.

The effect of "slamming" into that is of course ridiculously miniscule (like the gravity waves), but when you're talking about eternity - this too is a reason there'd be no such thing as an eternal orbit.

#4385270 - 10/16/17 02:31 PM Re: Gravitational waves - who knows about these? [Re: piper]  
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neutron star collision

Oct 2017
"For the first time, two neutron stars in a nearby galaxy have been observed engaging in a spiral death dance around one another until they collided. What resulted from that collision is being called an "unprecedented" discovery that is ushering in a new era of astronomy, scientists announced Monday .......This discovery of two neutron stars colliding to create the same type of waves, in addition to light, allowed astronomers to study gravitational waves in a new way. The signal lasted for 100 seconds, providing them with even more data and insight. It revealed that light and gravitational waves travel at the same speed"

http://www.cnn.com/2017/10/16/world/neutron-star-collision-gravitational-waves-light/index.html


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#4385276 - 10/16/17 03:29 PM Re: Gravitational waves - who knows about these? [Re: piper]  
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#4385294 - 10/16/17 05:25 PM Re: Gravitational waves - who knows about these? [Re: piper]  
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With regard to smaller gravitational wave influences, check out the photos of the edges of Saturns rings and gaps, where the gravitational waves of moons and moonlets kick up wakes in the rings:

https://en.wikipedia.org/wiki/Rings_of_Saturn#Keeler_Gap


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#4385366 - 10/16/17 11:27 PM Re: Gravitational waves - who knows about these? [Re: Zamzow]  
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Originally Posted by Zamzow
But black holes and neutron stars also have a LOT of inertia, so that'd cancel that out.


If that were true, how comes that since LIGO was switched on a year ago, already three major events have been recorded. Per your argument, no orbital bodies would ever spiral-cirle each other in all eternity. No, the effect ir more pronounced the more each body actually distorts spacetime (=the more mass it has). That's why two black holes can't orbit each other for as long as a small planet can circle a small star (effectively, forever).


Newtonian physicists need not apply when it comes to discussing gravity waves.

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