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Double Pulsar Discovered
jabberjaw writes "Nature is reporting that a set of two pulsars could be emitting gravitational waves. Einstein predicted the existence of gravitational waves in his general theory of relativity, but a gravitational wave has yet to be detected. Find out more about gravitational waves and pulsars at Eric Weisstein's World of Physics."
Gravitational waves have always been notoriously difficult to detect (infact near nigh impossible) because of their weak nature. This looks like a good opportunity to do that.
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Actually, Moore's Law originally refered to the number of transistors that could be packed onto an integrated circuit - it didn't directly refer to speed or size at all.
"Prefiero morir de pie que vivir siempre arrodillado!"
As an aside, with a system this unique, and not to sound too much like a loon, but perhaps we should look for an ET presence. Not as the creators, but there maybe unique physical process than can be exploited in such a system, and doing so may give off a detectable technological signature.
Letter To Iran
Here's a cool kid's site that has some animations
It's for the LISA (Laser Interferometer Space Antenna). Space.com did a story on it a little while back, and it was in a Scientific American, but I'm not sure which, I have too many lying around. Unfortunantly, it doesn't launch until 2009.
You can also download the entire thing if you like. I just spent 15 minutes digging all this up, figured I might save someone else that time.
1 afb6ae049ae214fc034aad839a91985ea187bea5786f362d84 1a61948bf2688f01f87fb6fdf0e7ceb61c22186fb/nova_eu_ 30[12-14]c[01-08]_mp4_300.mov" -o universe#1_#2.mov
Some previous Slashdotters showed us how (first link is to the highest quality download).
I got it to work fine with this (remove the spaces!):
curl "http://a768.g.akamai.net/5/768/142/3f9e9589/1a1a
When calculating the orbits of celestial bodies, it is necessary to assume that gravity is instantaneous. When an object moves, its gravity appears to move with it instantly. The earth appears to orbit the Sun's present position rather than where the sun appears to be due to speed-of-light delay.
As I understand it, though, there are two ways to look at it. The Earth is approximately 8 light-minutes from the Sun. The Earth is either orbiting the Sun's actual position, or it's orbiting a point that would be about eight minutes in front of the Sun's extrapolated path based on its position and momentum at that given instant.
It comes down to a question of whether or not gravity is a field or a particle. If it's a particle, then it must travel at some unimaginable speed. If it's a field then it would share some of the properties (like velocity and direction) of the object that generates it, and changes to the field would propagate outward from the object at the speed of light. These changes to an object's field of gravity are thought to produce "gravity waves" that have yet to be detected.
I could very well be muddled on this subject but I have done some reading on it. Please correct me if I'm wrong.
Fun with Anagarams! LADS HOST, SHALT DOS. HAS DOLTS. AD SLOTHS, HATS SOLD. ASS HO, LTD.
Let me ask you this, do you think you are lighter at noon and heavier at midnight because the Sun's gravity subtracts and adds to the Earth's? (It doesn't). You do not feel the affect of traveling along a curve, and wouldn't notice it was now a straight line, other than side effects that accumlate from lack of solar flux.
Letter To Iran
This is a myth.
Please learn some basic geology before making such claims.
What?
the same wave/particle duality will be observed as we see in photons
The "wave/particle duality" was resolved in the 50's with Quantum Electrodynamics. Photons are particles, and so (presumably) are gravitons. Yes, they sometimes behave in ways that are most conveniently described using concepts we're used to associating with waves (e.g., interference effects), but that doesn't mean that they are waves. To summarize - there is no wave/particle duality any more! Now, the problem is to define what is meant by "particle"...
Wrong. Hulse and Taylor's discovery was of a pulsar and companion neutron star. The companion was not a pulsar. This is the first known double pulsar system. One of the discoverers is a couple of doors down the corridor from me, so I can confirm this as true.
What is the inverse of the Matrix?
- The first is to photograph the upper atmosphere with an incredibly sensitive camera during night time, the reason is that gravity waves (that have a period of a few hours) cause the upper atmosphere to strech and compress causing the atoms that cause air glow to seporate into layers. this shows up on the image as bands. these gravity waves are emitted from the center of the earth.
- the second is to use an incredibly precise receiver tuned to a reliable transmitter in the HF bands, to a frequency that gets reflected by the ionosphere. since gravity waves will cause the ionosphere to expand and contract the change in velocity will cause the HF signal to be doppler shifted, meaning the gravity wave will be shown up in a slight variation of the incomming frequency.
the second option can be done by ham radio operators (if they really know there stuff), the first option is for universities since only they have the budget to buy the expensive equipment.simon
Strong Nuclear Force waves do exist. They are called "pions". Because the strong force is short-ranged, the pions manifest as particles with short lifetime for radioactive decay and nonzero mass. Nevertheless they do exist, both independently as particles and transiently inside atomic nuclei. I think you can find this kind of stuff discussed in books like Elementary Particles and the Laws of Physics: The 1986 Dirac Memorial Lectures
by Richard P. Feynman (Author), Steven Weinberg (Author) (Paperback) # Publisher: Cambridge Univ Pr (Trd); 0 edition
# ISBN: 0521658624
The existence of gravitational waves have been inferred (i.e. detected indirectly) from such things as the slowdown in the orbit of a pulsar in a binary system, implying that energy is being radiated away), but they have never detected directly.
"It comes down to a question of whether or not gravity is a field or a particle."
Neither. Gravity (as best we know) is a product of the warping/bending of spacetime, caused by the mass/density of an object. As matter and energy are considered the same thing, a dense source of energy and a dense source of matter... same thing.
Think of a sheet of flexible nylon fabric stretched tightly from four corners, suspended horizontally... call this space and time, the very fabric of the universe.
Next, drop a marble or stone into the center of your nylon spacetime, and it will form a circular, curved depression in the middle of you sheet. Call this the sun.
Notice that if you drop a smaller marble near or on the edge of your depression, it will role toward the epicenter of your warp, eventually hitting the first central marble. The warp in spacetime pulled the second marble toward the first.
If you put the second marble too far away from the first, outside the depression and subsequently outside its gravitational effect, it will just sit motionless on the nylon. But, note that this second marble makes a depression/gravity well of its own.
I'm really tired, and should be asleep, but that's a pretty good picture, I think.
Not a particle or a field. A curvature in space and time itself.
Peace
Right now we see a system 85M years from coalescing, that means in 85M years from today we will see it happen.
Besides, google search reveals that they are about 1600-2000 light-years away so you can pretty much ignore any questions of "now_here" against "now_there". 85M years +/- 2K years is still 85M years.
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- - You can't take something off the Internet! That's like trying to take pee out of a swimming pool.
Yes, it is a rather confusing analogy. The way to look at it is that the sheet is space itself. Draw lines on it, and each of these is a straight line. Now when you place the object in it and it curves the sheet, notice that the 'straight' lines are now curved by it. This is analogous to the mass warping space. The lines are now curved, and the 'straight' path of an object on this curved space is now going to curve as well.
Now imagine it in 3D.
As the air to a bird or the sea to a fish, so is contempt to the contemptible -W.B.
As for the faster-than-light communications, we could do that with tangled photons. Einstein was troubled by the fact that quantum entanglment causes an instantaneous change across a large distance.
I assume you're talking about the fact that two spin-1/2 particles generated in a single decay have entangled spin polarization states. These spin states cannot be used to transmit information faster than light. While it is true that the effect happens over arbitrarily large separations, the people doing the experiment must still communicate their results in order to use the information. Therefore, communication is still constrained by the speed of light.
Because matter is the minority substance in space, it will be space that is trying to displace matter.
To clarify - water is not trying to displace air because it is a minority substance, but because it is a less dense substance. The water pressure at a point is caused by all the water above that point pushing down (because of gravity). Therefore the water pressure at the bottom of the bubble is greater than the pressure at the top of the bubble, because there is more water above it, at the bottom than at the top.
Therefore the net force on the bubble due to water pressure is in the upward direction. The force of gravity on the bubble is not enough to counter this, and thus the total net force is still in the upward direction and so the bubble moves up.
The important part is that the only thing that causes the bubble to move is a difference in water pressure on one side of the bubble compared to the other.
But, what happens when you have two solid objects floating in space? Eventually, they will move toward each other because now the amount of space between the two objects is superseded by the increase in combined proportional mass relative to the two objects (however, the space on other side of both objects is now the majority).
Why? What causes this? And as far as bubble movement is concerned the only possible cause is differences in water pressure.
Say you had a bubble in some water. The water pressure to the left and right of it would be the same. Now place another bubble directly to the left of it. There is no reason for the water pressure between the two bubbles to suddenly drop. And yet that is what would have to happen if the bubbles were to be attracted to one another.
Furthermore, if two bubbles were moving towards each other this would cause the pressure between them to increase, which would actually apply a force to slow them down. The opposite would occur if bubbles are moving away from one another. So water pressure actually dampers any motion between bubbles.
In conclusion a pressure model does not predict an attractive force between two objects varying soley according to their their mass and distance from one another, which is what emperical gravity measurements tell us. Furthermore, it does predict a force which which is a result of their relative velocities, which is something we don't see in emperical data.
Sorry if I explained a lot of things you already understand but it's impossible for me to be aware of what you understand, since I don't know you.
Amendum. If a bubble was traveling through up through the water you might expect lower pressure than normal on either side of the bubble due to the movement of the water (simular to how a carburator works). However (at best - I haven't thought this through) this would only allow for attraction of bubbles perpendicular to their velocity vector, and would thus still not model gravity as we see it. Even stranger is that the potential force of "gravity" would be weaker the further you got from the center of the universe, since the matter-bubbles would be traveling more slowly (less space-gravity means less difference in pressure, hence less force). Another sticky point include the fact that it would create a canonical reference frame much like the concept of ether did, and would likely contradict relativity in many cases.
I find the book much more gratifying. Elegant Universe
Physics makes the world go 'round.