I hadn't considered thermodynamics, so unless the energy from beyond the observable horizon balanced the amount being lost..., oh I am going to have fun thinking about this. Though I still don't think causality would be violated if no information about the gravity wave could be determined beyond that it happened. You still wouldn't know where or what, maybe its intensity at best, and if all the waves from everywhere were being detected at once it most individual waves would be lost in the noise.
Yep, lots to think about.
Pity we have to wait till 2014, hopefully something big enough to detect, but not big enough to kill us, will happen nearby, or someone figures out how to improve the current hardware.
Yours is the clearest answer that actually applies to my question, thank you.
That said there are still a few things bugging me, if gravity waves affected all points within our space-time simultaneously, as they would if they had a c+ velocity, then they couldn't be used as a reference within that framework. No information about the source, direction or strength of a gravity wave could be detected by any instrument that was bound by a c constrained space-time framework, the energy would just be seen to "be everywhere at once", sort of like the Cosmic Background Radiation. Causality is preserved. All elements of the detector would be "hit" by the wave at the same time so how could you get any info about the wave?
The existence of gravity wave has been substantiated by observation, the energy loss in the orbits of two co-orbiting pulsars matches expected loss from gravity wave generation (sorry can't find a link just now), but nothing has ever been detected by any of interferometry based instruments. The math says the instruments should have detected something, it also says gravity waves exist. If the wave can move FTL they would exist and be undetectable by anything we can come up with using current tech.
Of course if one of the detectors every finds anything I'll rethink the whole thing again and may start another discussion on/. about something else.
Obvious doesn't always mean correct. Remember that it used to be "obvious" that the Sun went around the Earth.
Inflation may be "tenuous" but it has a fairly solid grounding in GR, as does the "warp drive" I mentioned, and both say that space-time can alter (stretch/deform) at FTL. Since a gravity wave is only a distortion of space-time why can't they move FTL?
There have been observations of a pair of co-orbiting pulsars that shows the energy loss of their orbits matches what is expected if gravity waves are being emitted. So I feel safe saying that they exist, but why haven't we detected any? All the math says we should have found something with the instruments we have, but those instruments are based on the assumption the GWs propagate at c. I have yet to hear anyone explain why they have to. Its just been assumed that since "matter and energy(*) can not move faster than light" gravity, which is a deformation of space, shares the c limit.
If gravity waves can propagate at c+ then it would explain why nothing has been detected, the entire interferometer based GW detector is affected simultaneously, the interference patterns wouldn't form.
(*)So far the only energy we have any experience with is electromagnetic energy, light itself, but gravity isn't EM.
I realize you put a bit of effort into that reply and I do appreciate it but you seem to have totally missed my question.
If space can deform/stretch FTL and gravity is a stretching/deformation of space why can't gravity waves propagate FTL?
I never said a mass could really appear out of nowhere, I asked what if it did? What would happen? Just a thought experiment, sort of like thinking about how to build a Ring World, it works on paper but no known material has the tensile strength to really build one.
Yes, Inflation is one of those "special" cases, but so are "black holes", and both have a fair amount of general acceptance. If you can discount one by saying its a "corner case" you can discount the other just as easily. I know of two other theorems that explain the super massive objects, currently called "black holes", to a precision that matches observation, without resorting to "special case" math.
"There's nothing instantaneous about gravity fluctuations.. they happen at the same speed as c."
could you link to something that proves that? That is what has me asking this, everyone is just assuming/stating that the deformation of space-time propagates at c but no one cites any proof. GR says gravity moves at c, it also says that space can deform at greater than c and that gravity waves are a deformation of space-time.
Kind of like saying a car has can only legally go 70mph on the freeway, but technically the car itself can go faster than 70mph on the test track, what part of GR keeps it from going 71mph on the freeway?
Why can't a gravity wave propagate faster than c? This is what I'm trying to understand.
Aside; the math of the "warp drive" works, even if the technology cant do it. Sort of like a Ring World, mathematically is a suspension bridge with no end points but no known material has the physical tensile strength to build it. It may never be possible in real life but on paper it works, and it says a point/volume of space can alter its position relative to other points FTL by deforming space-time, so why cant a gravity wave do the same thing? It could explain why no gravity waves have been detected, if the wave propagates FTL then there wouldn't be time for the interference patterns to alter in the interferometer.
But what part of GR says that the ripples in space-time have to move at the speed of light? That is what I don't get, if space-time can deform/stretch at FTL why can't the ripples propagate through the fabric of space-time FTL? What part of GR or even M says it can't happen?
This raises a question that has been on my mind for awhile. I hope I can explain this but I'm not an expert in physics so bear with me.
Also, please do not just say "Your wrong, GTR says that can't happen", you would be "citing authority" and it really kills the validity of your rebuttal. Sort of like saying "God exists because the Bible says so". Please explain WHY its wrong, as in cite what portion of GTR says it can't happen so I can read it and see where how I went wrong.
According to General Theory or Relativity, as defined in the link you posted, if a mass were to suddenly appear at a location in space-time, say in the forward Lagrange point of Jupiter's orbit, it would take X amount of time before the gravity from that mass would affect the orbits of the other planets in the Solar system. X being equal to time it would take for light to travel from the location of the mass to the rest of the planets in the Solar system.
Have I got it right so far?
But my understanding is that, according to GTR, gravity is caused by the deformation of space-time by a mass. So the mass that suddenly appeared would deform space-time around it, thus imposing a gravitational influence on all objects in range.
Here is what has me going "wait, what?"
Also according to GTR space-time can expand/contract at speeds greater than that of c in a vacuum, as described in the "inflation" theory of the early universe and Alcubierre's "warp drive" theory. Since the mass deforms space by "stretching" it wouldn't that mean that the influence of a mass could affect an object at a distance in less time than it would take light to travel that same distance? Since the "fabric" of space-time could alter faster than light can travel across it.
I'm hoping to get some insight into how I could be wrong, because based on what I know I can't see any reason why it can't happen. It could explain why we haven't detected gravity waves using interferometry, if the gravity wave, a distortion of space-time was moving faster than light it wouldn't be able to affect the phase of the light beams.
Thank you in advance to those who actually provide some useful info to help me improve my understanding.
While I understand the sentiments I would recommend that you watch "Witch Hunt" before fully supporting such a step.
36 convictions for child molestation, all overturned.
Opps, sorry, only 34 where overturned. The other 2 died in prison awaiting their retrial. The last guy was released after spending 20 years in jail for something he didn't do.
I understand what your saying, and I am trying to carry out the actions you suggest.
I'm just glad that a group of North American colonists back in the 1770's felt that sometimes a person had to risk self/family/friend for a greater whole.
Your response is what I expected. You gave an extreme example (bankruptcy/starvation) as justification of your position.
You are part of the problem and, as you say, there is no argument I can put forth to change your outlook.
If that is what you think then so be it. But you lose your right to bitch about the jury system when one of your relatives or friends gets shafted by a jury of idiots.
I agree that your job or business can get screwed up if the case your hearing drags on. But what is more important, your job or business, or an innocent persons Freedom?
What would also help would be if people who had actual intelligence didn't try so hard to get out of jury duty.
The reason we end up with juries composed of idiots, bigots and other people of questionable mental ability is they are the only ones who are "to dumb" to get out of jury duty.
If you want a fair system then be prepared to serve on a jury and not complain about it. The Constitution isn't a passive document, we all have to participate for it to work.
I never said Apple and Google weren't engaging in anti competitive activities, just pointing out to JoshuaZ that MS didn't didn't grow to where it is because of "outright success", according to the findings of a court of law they cheated.
How history will regard Google has yet to be written. As to Apple, well, I have a choice to not by a Mac. Do I have a choice to buy a netbook from HP without paying for a MS Windows license that I don't want? No, and I have tried.
True, but for that to work you have to log in first.
That makes it a special case solution, not a general one.
Over the years about the only thing that has been added to slashdot that made me go "Oh, that's kinda cool" was the +/- buttons to mess with the summary, which I ignore now since they don't do anything I care about. Other than that I have noticed that/. loads slower than it did 4 years ago on the same computer, and its not because of my OS being bogged down. Its not. When I first started reading/. I used dial up and it loaded almost as fast then than it does now with a DSL.
Ah, but my sig is a paraphrase, not a direct quote. Through maybe I should drop the quotation marks.
I could always go back to my sig about the affairs of dragons and ketchup but that just doesn't seem as social relevant to whats going on in the world today.
Another thought. Even a sonic round might OK with this system. If it tracks the report of the weapon then a suppressor could prove effective against this system since the sonic "crack" would be ignored/lost in the background noise at any significant distance.
The more of these that get deployed the more we are going to be hearing about suppressors being used. Criminals adapt to new tech, sometimes even faster than law enforcement does.
That is exactly what I was talking about with the gun/suppressor combo. The ones I've encountered that are manual action, often single shot, shooting custom sub-sonic loads, make less noise than a car driving past. Perfect for targeted hits where you only need the one shot.
The bling factor is indeed something to keep in mind. Your right about how most common street thugs are going to go with something that looks cool and is going to be relatively common, and it doesn't hurt if its been in the latest action movie either.
As to the acoustic signature that will set these things off I have to wonder, is the detector actually doing any signal processing to differentiate between a firecracker/back fire and an actual gunshot? If they have to pack that kind of DSP hardware into each unit that would explain the cost. If they don't you could potentially cover a shooting with a pack of firecrackers.
Slashdot Mirror
I hadn't considered thermodynamics, so unless the energy from beyond the observable horizon balanced the amount being lost ..., oh I am going to have fun thinking about this. Though I still don't think causality would be violated if no information about the gravity wave could be determined beyond that it happened. You still wouldn't know where or what, maybe its intensity at best, and if all the waves from everywhere were being detected at once it most individual waves would be lost in the noise.
Yep, lots to think about.
Pity we have to wait till 2014, hopefully something big enough to detect, but not big enough to kill us, will happen nearby, or someone figures out how to improve the current hardware.
Thanks again, have a good one.
Yours is the clearest answer that actually applies to my question, thank you.
/. about something else.
That said there are still a few things bugging me, if gravity waves affected all points within our space-time simultaneously, as they would if they had a c+ velocity, then they couldn't be used as a reference within that framework. No information about the source, direction or strength of a gravity wave could be detected by any instrument that was bound by a c constrained space-time framework, the energy would just be seen to "be everywhere at once", sort of like the Cosmic Background Radiation. Causality is preserved. All elements of the detector would be "hit" by the wave at the same time so how could you get any info about the wave?
The existence of gravity wave has been substantiated by observation, the energy loss in the orbits of two co-orbiting pulsars matches expected loss from gravity wave generation (sorry can't find a link just now), but nothing has ever been detected by any of interferometry based instruments. The math says the instruments should have detected something, it also says gravity waves exist. If the wave can move FTL they would exist and be undetectable by anything we can come up with using current tech.
Of course if one of the detectors every finds anything I'll rethink the whole thing again and may start another discussion on
Have a good one.
Obvious doesn't always mean correct. Remember that it used to be "obvious" that the Sun went around the Earth.
Inflation may be "tenuous" but it has a fairly solid grounding in GR, as does the "warp drive" I mentioned, and both say that space-time can alter (stretch/deform) at FTL. Since a gravity wave is only a distortion of space-time why can't they move FTL?
There have been observations of a pair of co-orbiting pulsars that shows the energy loss of their orbits matches what is expected if gravity waves are being emitted. So I feel safe saying that they exist, but why haven't we detected any? All the math says we should have found something with the instruments we have, but those instruments are based on the assumption the GWs propagate at c. I have yet to hear anyone explain why they have to. Its just been assumed that since "matter and energy(*) can not move faster than light" gravity, which is a deformation of space, shares the c limit.
If gravity waves can propagate at c+ then it would explain why nothing has been detected, the entire interferometer based GW detector is affected simultaneously, the interference patterns wouldn't form.
(*)So far the only energy we have any experience with is electromagnetic energy, light itself, but gravity isn't EM.
I realize you put a bit of effort into that reply and I do appreciate it but you seem to have totally missed my question.
If space can deform/stretch FTL and gravity is a stretching/deformation of space why can't gravity waves propagate FTL?
I never said a mass could really appear out of nowhere, I asked what if it did? What would happen? Just a thought experiment, sort of like thinking about how to build a Ring World, it works on paper but no known material has the tensile strength to really build one.
Yes, Inflation is one of those "special" cases, but so are "black holes", and both have a fair amount of general acceptance. If you can discount one by saying its a "corner case" you can discount the other just as easily. I know of two other theorems that explain the super massive objects, currently called "black holes", to a precision that matches observation, without resorting to "special case" math.
As you say, we have work to do. A lot of it.
"There's nothing instantaneous about gravity fluctuations.. they happen at the same speed as c."
could you link to something that proves that? That is what has me asking this, everyone is just assuming/stating that the deformation of space-time propagates at c but no one cites any proof. GR says gravity moves at c, it also says that space can deform at greater than c and that gravity waves are a deformation of space-time.
Kind of like saying a car has can only legally go 70mph on the freeway, but technically the car itself can go faster than 70mph on the test track, what part of GR keeps it from going 71mph on the freeway?
Why can't a gravity wave propagate faster than c? This is what I'm trying to understand.
Aside; the math of the "warp drive" works, even if the technology cant do it. Sort of like a Ring World, mathematically is a suspension bridge with no end points but no known material has the physical tensile strength to build it. It may never be possible in real life but on paper it works, and it says a point/volume of space can alter its position relative to other points FTL by deforming space-time, so why cant a gravity wave do the same thing? It could explain why no gravity waves have been detected, if the wave propagates FTL then there wouldn't be time for the interference patterns to alter in the interferometer.
That is just it, I don't think gravity waves are restricted propagate at c, what I asked was what part of GR explains why they can't?
Also, my current understanding is that energy will still deform space-time just as mass does so your right about that.
But what part of GR says that the ripples in space-time have to move at the speed of light? That is what I don't get, if space-time can deform/stretch at FTL why can't the ripples propagate through the fabric of space-time FTL? What part of GR or even M says it can't happen?
This raises a question that has been on my mind for awhile. I hope I can explain this but I'm not an expert in physics so bear with me.
Also, please do not just say "Your wrong, GTR says that can't happen", you would be "citing authority" and it really kills the validity of your rebuttal. Sort of like saying "God exists because the Bible says so". Please explain WHY its wrong, as in cite what portion of GTR says it can't happen so I can read it and see where how I went wrong.
According to General Theory or Relativity, as defined in the link you posted, if a mass were to suddenly appear at a location in space-time, say in the forward Lagrange point of Jupiter's orbit, it would take X amount of time before the gravity from that mass would affect the orbits of the other planets in the Solar system. X being equal to time it would take for light to travel from the location of the mass to the rest of the planets in the Solar system.
Have I got it right so far?
But my understanding is that, according to GTR, gravity is caused by the deformation of space-time by a mass. So the mass that suddenly appeared would deform space-time around it, thus imposing a gravitational influence on all objects in range.
Here is what has me going "wait, what?"
Also according to GTR space-time can expand/contract at speeds greater than that of c in a vacuum, as described in the "inflation" theory of the early universe and Alcubierre's "warp drive" theory. Since the mass deforms space by "stretching" it wouldn't that mean that the influence of a mass could affect an object at a distance in less time than it would take light to travel that same distance? Since the "fabric" of space-time could alter faster than light can travel across it.
I'm hoping to get some insight into how I could be wrong, because based on what I know I can't see any reason why it can't happen. It could explain why we haven't detected gravity waves using interferometry, if the gravity wave, a distortion of space-time was moving faster than light it wouldn't be able to affect the phase of the light beams.
Thank you in advance to those who actually provide some useful info to help me improve my understanding.
While I understand the sentiments I would recommend that you watch "Witch Hunt" before fully supporting such a step.
36 convictions for child molestation, all overturned.
Opps, sorry, only 34 where overturned. The other 2 died in prison awaiting their retrial. The last guy was released after spending 20 years in jail for something he didn't do.
I understand what your saying, and I am trying to carry out the actions you suggest.
I'm just glad that a group of North American colonists back in the 1770's felt that sometimes a person had to risk self/family/friend for a greater whole.
Your response is what I expected. You gave an extreme example (bankruptcy/starvation) as justification of your position.
You are part of the problem and, as you say, there is no argument I can put forth to change your outlook.
Good luck.
According to the Register he has been getting flak for it since training on the scanners last year.
Think you could shrug off that kind of teasing, true or not, for a year without wanting to bust some heads?
So, you want the benefits and Freedoms but not the responsibilities.
Why am I not surprised?
Will you feel the same when its one of your family or close friends who gets railroaded because of an idiot jury?
Yeah.
but then it would get you, and everyone else, off jury duty very quickly. Which seems to be what everyone wants.
Both.
Just think of the number of cannabis users who might be acquitted if the Jury knew of, and exercised, their right of Nullification?
If that is what you think then so be it.
But you lose your right to bitch about the jury system when one of your relatives or friends gets shafted by a jury of idiots.
I agree that your job or business can get screwed up if the case your hearing drags on. But what is more important, your job or business, or an innocent persons Freedom?
What would also help would be if people who had actual intelligence didn't try so hard to get out of jury duty.
The reason we end up with juries composed of idiots, bigots and other people of questionable mental ability is they are the only ones who are "to dumb" to get out of jury duty.
If you want a fair system then be prepared to serve on a jury and not complain about it. The Constitution isn't a passive document, we all have to participate for it to work.
I never said Apple and Google weren't engaging in anti competitive activities, just pointing out to JoshuaZ that MS didn't didn't grow to where it is because of "outright success", according to the findings of a court of law they cheated.
How history will regard Google has yet to be written. As to Apple, well, I have a choice to not by a Mac. Do I have a choice to buy a netbook from HP without paying for a MS Windows license that I don't want? No, and I have tried.
Breaking up companies always bugs me when the companies has grown primarily based on outright success.
How about a company that used its monopoly in a market to lock out and hurt competitors?
That is the big difference between Microsoft, Apple and Google. MS was convicted of monopoly abuse, the others have not.
Unfortunately in some places drawings can get you 20 years, no tentacles involved.
as seen here
True, but for that to work you have to log in first.
/. loads slower than it did 4 years ago on the same computer, and its not because of my OS being bogged down. Its not. When I first started reading /. I used dial up and it loaded almost as fast then than it does now with a DSL.
That makes it a special case solution, not a general one.
Over the years about the only thing that has been added to slashdot that made me go "Oh, that's kinda cool" was the +/- buttons to mess with the summary, which I ignore now since they don't do anything I care about. Other than that I have noticed that
Ah, but my sig is a paraphrase, not a direct quote. Through maybe I should drop the quotation marks.
I could always go back to my sig about the affairs of dragons and ketchup but that just doesn't seem as social relevant to whats going on in the world today.
Another thought. Even a sonic round might OK with this system. If it tracks the report of the weapon then a suppressor could prove effective against this system since the sonic "crack" would be ignored/lost in the background noise at any significant distance.
The more of these that get deployed the more we are going to be hearing about suppressors being used. Criminals adapt to new tech, sometimes even faster than law enforcement does.
That is exactly what I was talking about with the gun/suppressor combo. The ones I've encountered that are manual action, often single shot, shooting custom sub-sonic loads, make less noise than a car driving past. Perfect for targeted hits where you only need the one shot.
The bling factor is indeed something to keep in mind. Your right about how most common street thugs are going to go with something that looks cool and is going to be relatively common, and it doesn't hurt if its been in the latest action movie either.
As to the acoustic signature that will set these things off I have to wonder, is the detector actually doing any signal processing to differentiate between a firecracker/back fire and an actual gunshot? If they have to pack that kind of DSP hardware into each unit that would explain the cost. If they don't you could potentially cover a shooting with a pack of firecrackers.
Clean shot! From the middle of the ring and past the goalie for the winning point!!
Hey! we have almost the same sig! Way to go!