Chinese scientists find evidence for speed of gravity

[KRAIT]

NVM......................

 

[OrionHunter]

Speed of gravitational wave is equal to speed of light (atleast in theory). Why would you assume that its impossible for speed of gravitational force to be greater then light?

Well, according to Einstein's theory of Relativity, nothing can go faster than the speed of light - at least in our three dimensional universe.

 

[OrionHunter]

It is not to say that things cannot go faster than light. They may go. Weird things keep happening in the Universe. But Physics as we know cannot explain things that go faster than light. We need new theories.

Nope they cant! Nutrinos were thought to go faster, but what was the truth? The head of an experiment that appeared to show subatomic particles traveling faster than the speed of light had resigned from his post for falsifying results. (Some members of his group, called Opera, had wanted him to resign).

Prof Antonio Ereditato oversaw results that appeared to challenge Einstein's theory that nothing could travel faster than the speed of light.

Earlier in March, a repeat experiment found that the particles, known as neutrinos, did not exceed light speed.

 

[Not Sure]

How can anything in the universe travel FASTER than the speed of light? This is a bunch of unmitigated nonsense!

Secondly, the gravitational equation says that the force of gravity is proportional to the product of the two masses (m1 and m2), and inversely proportional to the square of the distance (r) between their centers of mass. Mathematically speaking,

F=Gm1m2 / r2,

where G is called the Gravitational Constant. It has a value of 6.6726 x 10-11 m3 kg-1 s-2.

Gravity is present everywhere in space thanks to Dark Matter which is responsible for mass in the universe. More the mass of an object, more the gravity. Where does speed come in?

The 'speed' of gravity doesn't figure in this at all. If the Chinese are correct, then we need to revisit this formula too.

A significant fact, usually overlooked, is that Newton’s law of gravity does not involve time.

Gravity must act instantly for the planets to orbit the Sun in a stable fashion. If the Earth were attracted to where the Sun appears in the sky, it would be orbiting a largely empty space because the Sun moves on in the 8.3 minutes it takes for sunlight to reach the Earth. If gravity operated at the speed of light all planets would experience a torque that would sling them out of the solar system in a few thousand years.

So much for the so called 'speed' of gravity!

If you ever read Principia Mathematica, you would realize that Newton never fully defined mass. He only meant mass as a quantity of matter, nothing else.

In simple terms, Newton said M is a Force, and Force = ma.

It is akin to saying that I live next door to my neighbor, and my neighbor lives next door to me. The statement is true, but I fail to provide the address of my house.

This, and his definition of this Universe as absolute, are the main reasons why Newtonian physics is considered obsolete.

Gravity is a quality of mass, and dark matter is not responsible for the gravitational force exerted by other massive objects.

The problem with the Chinese experiment is not related to the speed of gravity, which is less understood but not exactly a contentious issue as you are trying to present. Rather, the problem with this experiment is that unless they involved apparatus/instruments (as in LISA) that were laid over great distances at some particular time when some very strong gravitational waves were coming through (as in PULSARS), they can never detect the speed of gravity simply because gravity also warps space and time, so it would simply be impossible.

I am guessing the results of this Chinese experiment won't go too far.

 

[Jade]

Nope they cant! Nutrinos were thought to go faster, but what was the truth? The head of an experiment that appeared to show subatomic particles traveling faster than the speed of light had resigned from his post for falsifying results. (Some members of his group, called Opera, had wanted him to resign).

Prof Antonio Ereditato oversaw results that appeared to challenge Einstein's theory that nothing could travel faster than the speed of light.

Earlier in March, a repeat experiment found that the particles, known as neutrinos, did not exceed light speed.

Debatable...According to the mass-energy equivalence formula E = mc2, an object travelling at c would have infinite mass and would therefore require an infinite amount of energy to reach c. But in physical world there is no such thing as infinite. This is were the Einstein's theory of relatively fails. Another instances are black holes. Black holes gobbles up the light and don't emit them back. In other words, light cannot escape the gravity of back holes. So there is something thing that travels faster than light inside the Black hole.

'c' or speed of light is mathematical limitation and not a physical one

 

[KRAIT]

@Not Sure I am "NOT SURE" I will understand what you just posted.

But thanks for detailed explanation. More things to know.

 

[Not Sure]

@Not Sure I am "NOT SURE" I will understand what you just posted.

But thanks for detailed explanation. More things to know.

Oh it is perfectly alright KRAIT

I myself am not good at elaborating such topics without the use of the equations involved - that would make it a very complicated and boring post lol

What I basically meant was that Newton never defined mass. And that Newton thought of the Universe as absolute, which it is not. Einstein's theories are termed Relativity, because nothing is absolute and everything is taken with Relation to another.

For example, you draw a line and ask me whether it is short or long. I cannot say anything.

Then you draw another line beside it, and I can tell that Relative to the second line, the previous one is either short or long. Newton thought he could define that single line as short or long - that is not possible.



And I also meant to say that I am extremely skeptical of this Chinese experiment, because Gravitational waves that they are measuring, affect the time and distance as well. But speed itself is Distance/Time.

So I doubt it is possible for anyone sitting on Earth to measure the speed of the propagation of Gravitational waves with the help of Solar eclipses.

Happy New Year

 

[KRAIT]

@Not Sure Is Heisenberg principle applicable on gravitons ?

 

[Cielo]

Nothing new....General relativity predicts that the speed of a gravitational wave is equal to the speed of light. Since then there were many attempts to prove this prediction, but all resulting in failures. Let us see whether the efforts by Chinese will stand the scrutiny. But coming from Chinese I would take this with a pinch of salt

Indians can't do anything but the first to dismiss and laugh at others that try....no wonder you're country is behind China and will continue to do so for the rest of this century.

 

[Not Sure]

@Not Sure Is Heisenberg principle applicable on gravitons ?

I do not know much about gravitons, except for the fact that Hawking called them particles that carry negative energy.

However, with respect to Uncertainty Principle I do know one thing - It is not applicable to particles with negative energy.

So no, Heisenberg Principle will not apply to Gravitons, even if we were able to detect them.

 

[fast]

the source must have published something wrong..gravity is referred by acceleration which is rate of change of speed.the term "speed of gravity is absurd" may be it has to say rate of change of gravity

The speed of gravity refers to the speed of the effect of gravity. For example, we know the Sun's gravity pulls on the Earth constantly to make it orbit around the Sun. What if the Sun suddenly disappeared? Would the gravitational pull suddenly be gone? Would the Earth shoot off at a straight line off the orbit? Or would it continue to orbit until the gravitational effect is gone? The light from Sun takes about 8min and 19sec to reach the Earth. At the moment the Sun disappeared, there will be 8 more minutes of light to reach the Earth. Would it be the same for the gravitational effect?

So far all the theories have predicted the speed of gravity is the same as the speed of light in vacuum, but there's no experiment to prove it yet. I guess this one is attempting to provide an indirect proof measuring the tidal effect from the Moon and Sun.

 

[KRAIT]

The speed of gravity refers to the speed of the effect of gravity. For example, we know the Sun's gravity pulls on the Earth constantly to make it orbit around the Sun. What if the Sun suddenly disappeared? Would the gravitational pull suddenly be gone? Would the Earth shoot off at a straight line off the orbit? Or would it continue to orbit until the gravitational effect is gone? The light from Sun takes about 8min and 19sec to reach the Earth. At the moment the Sun disappeared, there will be 8 more minutes of light to reach the Earth. Would it be the same for the gravitational effect?
So far all the theories have predicted the speed of gravity is the same as the speed of light in vacuum, but there's no experiment to prove it yet. I guess this one is attempting to provide an indirect proof measuring the tidal effect from the Moon and Sun.

Will shoot off in the direction tangent to the elliptical orbit. No more centrifugal force.

 

[fast]

How can anything in the universe travel FASTER than the speed of light? This is a bunch of unmitigated nonsense!

Secondly, the gravitational equation says that the force of gravity is proportional to the product of the two masses (m1 and m2), and inversely proportional to the square of the distance (r) between their centers of mass. Mathematically speaking,

F=Gm1m2 / r2,

where G is called the Gravitational Constant. It has a value of 6.6726 x 10-11 m3 kg-1 s-2.

Gravity is present everywhere in space thanks to Dark Matter which is responsible for mass in the universe. More the mass of an object, more the gravity. Where does speed come in?

The 'speed' of gravity doesn't figure in this at all. If the Chinese are correct, then we need to revisit this formula too.

A significant fact, usually overlooked, is that Newton’s law of gravity does not involve time.

Gravity must act instantly for the planets to orbit the Sun in a stable fashion. If the Earth were attracted to where the Sun appears in the sky, it would be orbiting a largely empty space because the Sun moves on in the 8.3 minutes it takes for sunlight to reach the Earth. If gravity operated at the speed of light all planets would experience a torque that would sling them out of the solar system in a few thousand years.

So much for the so called 'speed' of gravity!

You need to brush up on your understanding of Astrophysics. The speed of light restriction only applies in the vacuum of space time. Space itself can certainly expand so fast that it causes two objects inside the space to move apart faster than the speed of light. Otherwise how do you think the universe can inflate into being in a fraction of a second right after the Big Bang? Guess what - the universe's space is now expanding in an ever faster speed and the outer galaxies will fly away in a faster than speed of light from us that we will not see them eventually.

Secondly, Newtonian understanding of gravity is so yester-century that I'm surprised you even brought it up in this discussion.

This so called 'speed' of gravity is a fact of life. Better learn about it before you spout ignorant nonsense next time.

Will shoot off in the direction tangent to the elliptical orbit. No more centrifugal force.

The question is when will it shoot off in the direction tangent to the elliptical orbit? Instantaneously the moment the Sun disappears or will it wait for 8min and 19sec before shooting off? The speed of gravity would answer that question.

 

[KRAIT]

@fast Interesting question. Can you tell me if there will be effect of earth's rotation in this case ?

 

[fast]

@fast Interesting question. Can you tell me if there will be effect of earth's rotation in this case ?

Interesting question. There are several aspects of it.

1. The Earth rotation was caused by its own gravity, as such its mass determines its centrifugal rotational force.

2. The Earth's internal matter has relatively even distribution throughout its volume so that it's not a case of one side has more mass (more gravity) than the other side. When the Sun pulls on the leading and trailing edges of the Earth on a rotation, both edges have about the same mass and thus Sun's pulls are the same and are canceled out. On the other hand, the Moon is small and has uneven internal matter and it's too close to the Earth that Earth's pull on it locks its rotation in sync with its revolution and one side of it is always facing the Earth. The Moon's side facing the Earth has more mass than the far side.

3. Even if there's a small uneven distribution of mass in Earth, the Sun is so far away from Earth that its gravity has extremely little net effect on the Earth's rotation compared to Earth's mass and its centrifugal rotational force. Sun's accelerating pull on the leading edge of the Earth and its decelerating pull on the trailing edge of the Earth have the same force and cancel out each other.

4. The Earth's rotation is slowing down, by very small bit every year. I don't remember it's due to the Sun's pull or other reasons like Earth's internal mass shifting around.

5. Back to the question, since the Sun's gravity has little effect on Earth's rotation, when it disappears, the absence of its gravity would have no effect on Earth's rotation. Earth will continue to rotate as before. Just that it will be a long night with no morning.