Scientific 'things you've always wanted to know' thread
Discussion
BarnatosGhost said:
Fascinating. What kind of experiment was constructed to measure the speed of gravity?
They're too complex for me but from memory involve measuring the orbital decay of various bodies and measuring the decrease in energy due to gravitational pull. I'm sure they had some tricky method of finding the speed from this - I think the most accurate measurement was C+/- 1% (edit, that's the wrong notation as it can't be +, but within 1% of C anyway)From Wikipedia, observations strongly suggest general relativity is correct;
[i]
As it turned out, the Jovian weather cooperated, and everything did go well, until the big day itself. On September 8, the telescope at Saint Croix malfunctioned because of serious tape recording problems. Fortunately, it turned out that the data from other telescopes could compensate for the loss. Although Kopeikin and Fomalont also had to discard about 15 percent of their data because of bad weather on Earth, this still left enough data to carry out the analysis. They compared the position of J0842+1835 on September 8, 2002, with its average position on the off-Jupiter days. Plugging this into Kopeikin's formula for the gravitational field of the moving Jupiter gave them the answer they were looking for. Kopeikin and Fomalont became the first two people to quantitatively measure the speed of gravity, one of the fundamental constants of nature. They found that gravity does move at the same speed as light. Their actual figure was 1.06 times the speed of light, but there was an error of plus or minus 0.21. The results were then announced at the 2002 American Astronomical Society annual meeting in Seattle, Washington.[/i]
[i]
As it turned out, the Jovian weather cooperated, and everything did go well, until the big day itself. On September 8, the telescope at Saint Croix malfunctioned because of serious tape recording problems. Fortunately, it turned out that the data from other telescopes could compensate for the loss. Although Kopeikin and Fomalont also had to discard about 15 percent of their data because of bad weather on Earth, this still left enough data to carry out the analysis. They compared the position of J0842+1835 on September 8, 2002, with its average position on the off-Jupiter days. Plugging this into Kopeikin's formula for the gravitational field of the moving Jupiter gave them the answer they were looking for. Kopeikin and Fomalont became the first two people to quantitatively measure the speed of gravity, one of the fundamental constants of nature. They found that gravity does move at the same speed as light. Their actual figure was 1.06 times the speed of light, but there was an error of plus or minus 0.21. The results were then announced at the 2002 American Astronomical Society annual meeting in Seattle, Washington.[/i]
carmonk said:
Zad said:
To be totally out of the earth's gravity is impossible.
[pedantic mode on]Actually most things are completely outside of the earth's gravity. Only that stuff that's in a 4.5bn light year radius of earth is affected by Earth's gravity[/pedantic mode off]R300will said:
carmonk said:
Zad said:
To be totally out of the earth's gravity is impossible.
[pedantic mode on]Actually most things are completely outside of the earth's gravity. Only that stuff that's in a 4.5bn light year radius of earth is affected by Earth's gravity[/pedantic mode off]Why are the four inner planets of the Solar System made of Rocky/Silicate/metallic material.
And the outer 4 giants made mostly of gas?
I don't understand why this is. The solar system was created from the same dusty/gas nebula.
Proximity to the sun? Or relating to the sun's gravity in any way?
And the outer 4 giants made mostly of gas?
I don't understand why this is. The solar system was created from the same dusty/gas nebula.
Proximity to the sun? Or relating to the sun's gravity in any way?
carmonk said:
That's absolutely not true. It sounds like you're talking about entanglement which is nothing to do with gravity and transmits no information. Gravity, to the best of our knowledge, cannot propogate faster than light.
No my point is that given that all of the atoms in the universe were made around the same time then they all share a gravitational attraction to each other no matter how far they have spread apart since then. R300will said:
carmonk said:
That's absolutely not true. It sounds like you're talking about entanglement which is nothing to do with gravity and transmits no information. Gravity, to the best of our knowledge, cannot propogate faster than light.
No my point is that given that all of the atoms in the universe were made around the same time then they all share a gravitational attraction to each other no matter how far they have spread apart since then. carmonk said:
R300will said:
carmonk said:
That's absolutely not true. It sounds like you're talking about entanglement which is nothing to do with gravity and transmits no information. Gravity, to the best of our knowledge, cannot propogate faster than light.
No my point is that given that all of the atoms in the universe were made around the same time then they all share a gravitational attraction to each other no matter how far they have spread apart since then. Also as you said particles cannot travel faster than light so they will not be able to 'outrun' the gravitational forces between them regardless of the expansion between them.
If you anihalated one particle with its anti partner you would have to bring them close together so that they could interract. They would both experience corresponding gravitational forces.
R300will said:
carmonk said:
R300will said:
carmonk said:
That's absolutely not true. It sounds like you're talking about entanglement which is nothing to do with gravity and transmits no information. Gravity, to the best of our knowledge, cannot propogate faster than light.
No my point is that given that all of the atoms in the universe were made around the same time then they all share a gravitational attraction to each other no matter how far they have spread apart since then. Also as you said particles cannot travel faster than light so they will not be able to 'outrun' the gravitational forces between them regardless of the expansion between them.
If you anihalated one particle with its anti partner you would have to bring them close together so that they could interract. They would both experience corresponding gravitational forces.
My point about the connection is that it needs to be just that, 'a connection', and not just 'once connected'. So if I do something to particle A it must reflect in particle B. Otherwise they can't be said to be connected, at least not in the way we mean it. And yes, it might (might) be possible to argue that two particles were once connected and therefore can be said, theoretically, to be still connected, but if you can't verify that connection experimentally then science says no.
Regarding the annihilation I was thinking about annihilating a particle with a particle of anti-matter, not necessarily its own anti-particle. Or just removing it from the universe (not easy, but it's the concept we're bothered about).
carmonk said:
Well it was space that was (and is) expanding FTL, not the things in it. Gravity helps things clump together so that objects don't just get bigger but less dense but there's no limit on the speed the actual fabric of spacetime can expand, or so I gather.
My point about the connection is that it needs to be just that, 'a connection', and not just 'once connected'. So if I do something to particle A it must reflect in particle B. Otherwise they can't be said to be connected, at least not in the way we mean it. And yes, it might (might) be possible to argue that two particles were once connected and therefore can be said, theoretically, to be still connected, but if you can't verify that connection experimentally then science says no.
Regarding the annihilation I was thinking about annihilating a particle with a particle of anti-matter, not necessarily its own anti-particle. Or just removing it from the universe (not easy, but it's the concept we're bothered about).
However you cannot annihilate any particle with any other particle of anti matter. It has to be proton vs anti-proton etc.My point about the connection is that it needs to be just that, 'a connection', and not just 'once connected'. So if I do something to particle A it must reflect in particle B. Otherwise they can't be said to be connected, at least not in the way we mean it. And yes, it might (might) be possible to argue that two particles were once connected and therefore can be said, theoretically, to be still connected, but if you can't verify that connection experimentally then science says no.
Regarding the annihilation I was thinking about annihilating a particle with a particle of anti-matter, not necessarily its own anti-particle. Or just removing it from the universe (not easy, but it's the concept we're bothered about).
Also given that they were all created around the same time i think it is easy to assume that gravity was felt between all of them. My question would be that even though space time may be expanding between these particles then unless they move with it (i.e FTL which wouldn't be possible) then how can they outrun the force of gravity between them?
R300will said:
carmonk said:
Well it was space that was (and is) expanding FTL, not the things in it. Gravity helps things clump together so that objects don't just get bigger but less dense but there's no limit on the speed the actual fabric of spacetime can expand, or so I gather.
My point about the connection is that it needs to be just that, 'a connection', and not just 'once connected'. So if I do something to particle A it must reflect in particle B. Otherwise they can't be said to be connected, at least not in the way we mean it. And yes, it might (might) be possible to argue that two particles were once connected and therefore can be said, theoretically, to be still connected, but if you can't verify that connection experimentally then science says no.
Regarding the annihilation I was thinking about annihilating a particle with a particle of anti-matter, not necessarily its own anti-particle. Or just removing it from the universe (not easy, but it's the concept we're bothered about).
However you cannot annihilate any particle with any other particle of anti matter. It has to be proton vs anti-proton etc.My point about the connection is that it needs to be just that, 'a connection', and not just 'once connected'. So if I do something to particle A it must reflect in particle B. Otherwise they can't be said to be connected, at least not in the way we mean it. And yes, it might (might) be possible to argue that two particles were once connected and therefore can be said, theoretically, to be still connected, but if you can't verify that connection experimentally then science says no.
Regarding the annihilation I was thinking about annihilating a particle with a particle of anti-matter, not necessarily its own anti-particle. Or just removing it from the universe (not easy, but it's the concept we're bothered about).
Also given that they were all created around the same time i think it is easy to assume that gravity was felt between all of them. My question would be that even though space time may be expanding between these particles then unless they move with it (i.e FTL which wouldn't be possible) then how can they outrun the force of gravity between them?
Consider this question: Work = Force X Distance, thus, an object weighing 10 lbs. raised vertically a distance of 1 foot, requires 10 Ft.Lbs. of work to accomplish.
Similarly, a person attempting, unsuccessfully, to raise an extremely heavy object off it's resting place and up in the air, experiences in due time, muscle fatigue, perhaps pain, and will definitely attest to having performed "Work", even though the "Distance" moved in the equation is "Zero". Can a person, then, perform "Work" involving no motion? impish
Similarly, a person attempting, unsuccessfully, to raise an extremely heavy object off it's resting place and up in the air, experiences in due time, muscle fatigue, perhaps pain, and will definitely attest to having performed "Work", even though the "Distance" moved in the equation is "Zero". Can a person, then, perform "Work" involving no motion? impish
impish said:
Consider this question: Work = Force X Distance, thus, an object weighing 10 lbs. raised vertically a distance of 1 foot, requires 10 Ft.Lbs. of work to accomplish.
Similarly, a person attempting, unsuccessfully, to raise an extremely heavy object off it's resting place and up in the air, experiences in due time, muscle fatigue, perhaps pain, and will definitely attest to having performed "Work", even though the "Distance" moved in the equation is "Zero". Can a person, then, perform "Work" involving no motion? impish
That's because you are ignoring all the other 'work' that is going on.Similarly, a person attempting, unsuccessfully, to raise an extremely heavy object off it's resting place and up in the air, experiences in due time, muscle fatigue, perhaps pain, and will definitely attest to having performed "Work", even though the "Distance" moved in the equation is "Zero". Can a person, then, perform "Work" involving no motion? impish
So, if Gravity travels at C'ish. The guys at CERN think they have a particle that travels faster than C.
Could this be the begginings of an Anti-Gravity system? And if an Anti Grqavity System were created would it therefore enable travel across vast distances (eg - 1000LY) in a more acceptable time frame (1 month). Considering that it is negating the effect of the force which actually holds the entire Universe together?
Could this be the begginings of an Anti-Gravity system? And if an Anti Grqavity System were created would it therefore enable travel across vast distances (eg - 1000LY) in a more acceptable time frame (1 month). Considering that it is negating the effect of the force which actually holds the entire Universe together?
AshVX220 said:
So, if Gravity travels at C'ish. The guys at CERN think they have a particle that travels faster than C.
Could this be the begginings of an Anti-Gravity system? And if an Anti Grqavity System were created would it therefore enable travel across vast distances (eg - 1000LY) in a more acceptable time frame (1 month). Considering that it is negating the effect of the force which actually holds the entire Universe together?
They would need to discover a particle with negative mass for true anti gravity. It's something that has been treated quite seriously as a future potential propulsion system by NASA and is called a Diametric drive.Could this be the begginings of an Anti-Gravity system? And if an Anti Grqavity System were created would it therefore enable travel across vast distances (eg - 1000LY) in a more acceptable time frame (1 month). Considering that it is negating the effect of the force which actually holds the entire Universe together?
plasticpig said:
AshVX220 said:
So, if Gravity travels at C'ish. The guys at CERN think they have a particle that travels faster than C.
Could this be the begginings of an Anti-Gravity system? And if an Anti Grqavity System were created would it therefore enable travel across vast distances (eg - 1000LY) in a more acceptable time frame (1 month). Considering that it is negating the effect of the force which actually holds the entire Universe together?
They would need to discover a particle with negative mass for true anti gravity. It's something that has been treated quite seriously as a future potential propulsion system by NASA and is called a Diametric drive.Could this be the begginings of an Anti-Gravity system? And if an Anti Grqavity System were created would it therefore enable travel across vast distances (eg - 1000LY) in a more acceptable time frame (1 month). Considering that it is negating the effect of the force which actually holds the entire Universe together?
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