# QuestionI have a question about gravitational waves

#### AnAverageIndianBoy

What happens when two gravitational waves collide ?????

#### Helio

They most likely behave as rolling ocean waves where they simply pass through one another. Their peaks would combine for a moment to create a stronger stretch of spacetime. But unlike waves of light that have particle-like properties, gravity waves with their longer wavelengths have no or very limited particle-like behavior, as far as I know.

Gravity waves are all over the universe and are encountering one another all the time. It's amazing how far they can travel and the ones LIGO has found, now others, have come from distances of a billion light years. Their amplitude decreases in a linear way, so if they travel, say, 10 times farther, they will have 1/10 of that amplitude, but not 1/100th as in the inverse square law.

#### AnAverageIndianBoy

Thnk you very much!!!

#### Dave643

They most likely behave as rolling ocean waves where they simply pass through one another. Their peaks would combine for a moment to create a stronger stretch of spacetime. But unlike waves of light that have particle-like properties, gravity waves with their longer wavelengths have no or very limited particle-like behavior, as far as I know.

Gravity waves are all over the universe and are encountering one another all the time. It's amazing how far they can travel and the ones LIGO has found, now others, have come from distances of a billion light years. Their amplitude decreases in a linear way, so if they travel, say, 10 times farther, they will have 1/10 of that amplitude, but not 1/100th as in the inverse square law.
Wow ok, what effect will all those overlapping gravity waves have as they pass the last object of mass in the universe at the expansion front of the universe. As they and light will be at the expansion front of the universe.
I assume gravity is still directional, as in its effect is constant it’s attracting mass to the mass that created it. However distant.

can all those waves increase and amplify each other To pull at, what’s outside the universe to increase the speed of the universes expansion?
I assume that gravity in the universe is increasing as the mass of the universe increasingly gets drawn to blackholes which increase the strength of there gravity they Exert on there Galaxy then the universe.
so, Increasing Gravity is as far as I can tell Is the only change the universe Has had that may increase the rate of expansion is that A right or wrong assumption?

#### IG2007

##### "Don't criticize what you can't understand..."
Wow ok, what effect will all those overlapping gravity waves have as they pass the last object of mass in the universe at the expansion front of the universe. As they and light will be at the expansion front of the universe.
I assume gravity is still directional, as in its effect is constant it’s attracting mass to the mass that created it. However distant.

can all those waves increase and amplify each other To pull at, what’s outside the universe to increase the speed of the universes expansion?
I assume that gravity in the universe is increasing as the mass of the universe increasingly gets drawn to blackholes which increase the strength of there gravity they Exert on there Galaxy then the universe.
so, Increasing Gravity is as far as I can tell Is the only change the universe Has had that may increase the rate of expansion is that A right or wrong assumption?
Coming to your first question, the effect that it always has. Like, if you imagine, there are gravitational waves colliding everywhere. The chair and the table also have gravitational waves, they are also colliding, but, according to our naked eye, they aren't getting anywhere closer. Why? Because, the Earth, the heaviest object nearby is pulling it with it's own gravitational waves and that is why we all are standing. Now you may think, the Sun is also pulling us, so why ain't we pulled towards the Sun? Well, O strange universe, it's because of friction, in my opinion. The Sun is really really far away from us (well, only if you are talking in AUs). The gravitational waves that it is creating take 8 minutes 19 seconds to reach the Earth. And, within that time they collide with many other objects present in space before they reach us, id est, dark matter, hydrogen, helium etc. And yes, gravity is a vector quanity.

And, No. Energy cannot be created nor can it be destroyed, according to the 1st Law of Thermodynamics. And as Einstein said, Energy is equal to mass multiplied by speed of light in vacuum-square, it is applicable to mass as well. So, mass cannot be created. And gravity doesn't push the universe, it crushes it. Literally. It binds the universe. It's not gravity that is expanding the universe, it is dark energy. And now, don't confuse dark matter and dark energy, they are (most probably) not related. Dark matter is matter that is not detectable by baryonic matter, but have gravity. And Dark energy is neither detectable nor has gravity, but something opposite to it which we yet don't know.

There is nothing outside the universe, if the universe is really a "universe". Universe literally means, "the one place where everything is". If you think that there is something beyond everything, I don't know. And, there are theories that the universe is infinite, and if it is infinite, then, as we all know, infinity + anything = infinity. Thus, the universe never increases nor decreases in size. And so, your assumption is wrong, I am sorry.

#### Dave643

Coming to your first question, the effect that it always has. Like, if you imagine, there are gravitational waves colliding everywhere. The chair and the table also have gravitational waves, they are also colliding, but, according to our naked eye, they aren't getting anywhere closer. Why? Because, the Earth, the heaviest object nearby is pulling it with it's own gravitational waves and that is why we all are standing. Now you may think, the Sun is also pulling us, so why ain't we pulled towards the Sun? Well, O strange universe, it's because of friction, in my opinion. The Sun is really really far away from us (well, only if you are talking in AUs). The gravitational waves that it is creating take 8 minutes 19 seconds to reach the Earth. And, within that time they collide with many other objects present in space before they reach us, id est, dark matter, hydrogen, helium etc. And yes, gravity is a vector quanity.

And, No. Energy cannot be created nor can it be destroyed, according to the 1st Law of Thermodynamics. And as Einstein said, Energy is equal to mass multiplied by speed of light in vacuum-square, it is applicable to mass as well. So, mass cannot be created. And gravity doesn't push the universe, it crushes it. Literally. It binds the universe. It's not gravity that is expanding the universe, it is dark energy. And now, don't confuse dark matter and dark energy, they are (most probably) not related. Dark matter is matter that is not detectable by baryonic matter, but have gravity. And Dark energy is neither detectable nor has gravity, but something opposite to it which we yet don't know.

There is nothing outside the universe, if the universe is really a "universe". Universe literally means, "the one place where everything is". If you think that there is something beyond everything, I don't know. And, there are theories that the universe is infinite, and if it is infinite, then, as we all know, infinity + anything = infinity. Thus, the universe never increases nor decreases in size. And so, your assumption is wrong, I am sorry.
The suns gravity is negated in the same way that the space station negates earths gravity, with its speed of orbit.
I don’t see friction as having any part in it.

when I say expansion of the universe it’s Imprecise What I mean is what’s out side that what we call the universe and it is expanding into.
This could be space time and as the mass of our universe Concentrates into fewer and fewer areas gravity is increasing, so that means space time is increasing.
If we take it after the Big Bang most matter was dust until it started to Coalesce under its own gravity the only thing increasing since the Big Bang is gravity. Not matter and energy but the density of matter.
Like a neutron star which is an exploded super massive star it losses mass in the explosion yet its gravity increases so what changed matter got denser more tightly packed as it were.

so gravity will always increase as the universe get more dense.
I also think gravity is the cause of the increase in the rate of the expansion of the universe because gravity can cancel gravity even if only briefly.

if I spin two galaxies on gravity they will orbit them selves, in one way or another but if gravity from a third source Interferes with their gravity relationship then those galaxies will change there orbit.
so we have galaxies emitting more and more gravity this can weaken the gravity by cancelling gravity out creating new stronger Lagrangian points that effects how the galaxies connect to form the universe. More Lagrangian points the faster the orbits can change, the earth if the suns gravity was interrupted by a new source of gravity that created a Lagrangian point to form around the earth, it would let the earth fly true which is always in a Straight line. We only fly in an Curving orbit because of the suns gravity.

again this maybe total wrong but it’s how I understand what I have read about our earths orbit. And that of our satellites that’s why they have to be traveling so fast in orbit. The that the speed of the orbit depends on the height of orbit they are required to maintain.

IG2007

#### IG2007

##### "Don't criticize what you can't understand..."
I would like to request @Catastrophe to make Dave understand the thing. I have some school work to do.

#### Helio

Gravity is treated as a “field effect”. Like a magnetic field, the attractive force increases as the two objects (iron & magnet) get closer. Our friend Galileo, using inclined planes, demonstrated that the attraction followed what we call today the inverse square law, so doubling distance would reduce the attractive force by 2x2...4.

Think of a bowling ball on a trampoline. The ball (Sun) when gently placed on the trampoline’s center will produce a gravity well (field) causing the marbles (planets) to begin to fall directly to the center. But if the marbles were rolled onto the trampoline after the ball was placed they would experience two forces that would give them orbital behavior— gravity and centrifugal action.

But if you violently drop the bowling ball onto the trampoline where marbles are sitting idle, what happens? The resulting wave action that is quickly propagating from the ball toward the marbles represents a gravity wave caused by the violent action of bh mergers.

The size of the wave, however, is unimaginably wimpy unless your near the event. Think how much (little) your neighbors trampoline would move once you drop the ball on yours. LIGO must measure space to move by a fraction of the width of a proton to detect monster events from far away.

#### Catastrophe

##### "Science begets knowledge, opinion ignorance.
Gosh IG, I'll have to understand it first myself. I'll have a look.

dfjchem721

#### Catastrophe

##### "Science begets knowledge, opinion ignorance.
Looks like Helio has done a pretty good job there!

dfjchem721

#### IG2007

##### "Don't criticize what you can't understand..."
Looks like Helio has done a pretty good job there!
Seems so. And, I quite like Helio's exogenesis there.

Catastrophe

#### Dave643

Gravity is treated as a “field effect”. Like a magnetic field, the attractive force increases as the two objects (iron & magnet) get closer. Our friend Galileo, using inclined planes, demonstrated that the attraction followed what we call today the inverse square law, so doubling distance would reduce the attractive force by 2x2...4.

Think of a bowling ball on a trampoline. The ball (Sun) when gently placed on the trampoline’s center will produce a gravity well (field) causing the marbles (planets) to begin to fall directly to the center. But if the marbles were rolled onto the trampoline after the ball was placed they would experience two forces that would give them orbital behavior— gravity and centrifugal action.

But if you violently drop the bowling ball onto the trampoline where marbles are sitting idle, what happens? The resulting wave action that is quickly propagating from the ball toward the marbles represents a gravity wave caused by the violent action of bh mergers.

The size of the wave, however, is unimaginably wimpy unless your near the event. Think how much (little) your neighbors trampoline would move once you drop the ball on yours. LIGO must measure space to move by a fraction of the width of a proton to detect monster events from far away.

As I said and you explained Using the bowling ball on a trampoline experiment that’s been running in a vacuum since our solar system settled into its current structure. The marbles at running around holding there orbits balancing the suns gravity with motion. In you experiment the slope caused by the bowling ball by using forward speed. To over come the slope ( gravity)
While I get that gravity from outside our solar system is wimpy, it still holds our Galaxy together At some level, maybe not on its own but at some level.
so increasing gravity due to the inevitable fact that all matter will fall into a gravity well of some type at some point. Has to be effecting our universe, at the time of the Big Bang we only had tiny particles now we have planets blackholes etc. That was at least in part gravity.
the gravities effect on our universe is only going to grow.

thanks for the comments and replies

#### Helio

With the discovery that our universe has accelerating expansion allows the view that DE is overcoming the grav field, which becomes weaker as spacetime continues to expand. Gravity was greatest at the first moment of the Bang. As mass separates, that inverse square law becomes non-trivial.

. iPhone

#### Dave643

With the discovery that our universe has accelerating expansion allows the view that DE is overcoming the grav field, which becomes weaker as spacetime continues to expand. Gravity was greatest at the first moment of the Bang. As mass separates, that inverse square law becomes non-trivial.

. iPhone
I assume you think that, due to the size of the universe at the big bangs start point, even with with the absence of neutron stars and blackholes at that time. We would have a lot of matter and energy in a relatively small area. as you said In the first moments.

while at this point black hole have formed that matter and energy into rotating galaxies, in the expanding universe theory where the universe is bigger than it should be as in if it was just expanding at light speed, the expansion Is faster than light speed and the inside is like a muffin in an oven where the blueberry’s in it are our galaxies and they expand out faster than expected due to being carried with the muffin’s enlargement I would say that’s only due to gravity, gravity is the pastry part of the expanding universe and it has carried galaxies on the expansion wave so for all we know the expansion front of the universe has massive gravity of its own.

it’s great debating with you all.
I don’t hold any of my opinions on these topics as in the remotest chance they are correct so don’t worry if you disagree just tell me why. And what you believe it is I say that because I know, no one knows or understands. If they think they do they are more than likely wrong lol.
We are not remotely close to understanding it all yet.

#### dfjchem721

They most likely behave as rolling ocean waves where they simply pass through one another. Their peaks would combine for a moment to create a stronger stretch of spacetime. But unlike waves of light that have particle-like properties, gravity waves with their longer wavelengths have no or very limited particle-like behavior, as far as I know.

Gravity waves are all over the universe and are encountering one another all the time. It's amazing how far they can travel and the ones LIGO has found, now others, have come from distances of a billion light years. Their amplitude decreases in a linear way, so if they travel, say, 10 times farther, they will have 1/10 of that amplitude, but not 1/100th as in the inverse square law.

It is going to be interesting to find out, assuming ESA gets LISA* in place, how much "back-ground" GWs there will be. Apparently everything is putting out GWs. Have read the solar system puts out 5,000 watts of GWs.

Simplistically , one might assume that all these waves interacting with each other would cause substantial distortions. It seems that they should behave in a similar fashion to other waves, with constructive and destructive interactions boosting or reducing each signal, depending on factors like vectors etc. Or do they just ride through each other and run along as if they never met?

If they interact and alter signal strength, it would seem to put significant constraints on the ability to detect smaller objects due to some level of pervasive "GW background", depending on one's position in a galaxy, and even the Universe. Anybody have any ideas about a predicted noise level?

* https://en.wikipedia.org/wiki/Laser_Interferometer_Space_Antenna

#### Helio

I assume you think that, due to the size of the universe at the big bangs start point, even with with the absence of neutron stars and blackholes at that time. We would have a lot of matter and energy in a relatively small area. as you said In the first moments.
In those very early moments, temperatures were perhaps near a trillion degrees, where only energy itself exists. As it cooled came quarks, then came electrons and protons and neutrons. Finally, as the universe continued its expansion, came atoms.

while at this point black hole have formed that matter and energy into rotating galaxies, in the expanding universe theory where the universe is bigger than it should be as in if it was just expanding at light speed, the expansion
The expansion was very isotropic so I don't think any massive black holes would fit within the model. I could be wrong, admittedly.

, gravity is the pastry part of the expanding universe and it has carried galaxies on the expansion wave so for all we know the expansion front of the universe has massive gravity of its own.
Gravity is throughout space but it isn't space. Mass affects space, and its effects we call gravity.

Dave643

#### Helio

Simplistically , one might assume that all these waves interacting with each other would cause substantial distortions.
The monster merger of two BHs stretched LIGO's 1km calibrated distance by a fraction of the width of a proton. I wouldn't spend money on any GW surfboard.

It seems that they should behave in a similar fashion to other waves, with constructive and destructive interactions boosting or reducing each signal, depending on factors like vectors etc. Or do they just ride through each other and run along as if they never met?
I think both are true, two intersecting waves will briefly combine and subtract as they pass but I can't imagine any sort of coupling action where one would be altered.

#### dfjchem721

I think both are true, two intersecting waves will briefly combine and subtract as they pass but I can't imagine any sort of coupling action where one would be altered.

Not sure I follow your answer about combining and subtracting......but then not being altered. Subtracting should not be a transient effect on the wave. After passing, they should be altered based on wave interference.

So, if two identical GWs meet "head on" 180 degrees out of phase, if destructive interference functions for these waves of space-time, then they should cancel each other out. Wasn't sure about this so I looked it up. GWs interact with each other like all other physical wave forms. They engage in constructive and destructive interference.

This is stolen from Wiki:

"Interference effects can be observed with all types of waves, for example, light, radio, acoustic, surface water waves, gravity waves, or matter waves. "

It would seem that a lot of GWs of ~ low strength are being modified by such interference, and this will show up as background "noise". One might suspect LISA will be tested with substantial noise, if it ever gets deployed. Of course if a given GW is powerful enough to get through the noise, it can be detected, as has already been done. That is the whole reason for deploying such a large array in space. It was that interference issue that was eating away at me since GWs and the fields that produce them are the most enigmatic physical forces in the universe.

Dave643

#### Dave643

Not sure I follow your answer about combining and subtracting......but then not being altered. Subtracting should not be a transient effect on the wave. After passing, they should be altered based on wave interference.

So, if two identical GWs meet "head on" 180 degrees out of phase, if destructive interference functions for these waves of space-time, then they should cancel each other out. Wasn't sure about this so I looked it up. GWs interact with each other like all other physical wave forms. They engage in constructive and destructive interference.

This is stolen from Wiki:

"Interference effects can be observed with all types of waves, for example, light, radio, acoustic, surface water waves, gravity waves, or matter waves. "

It would seem that a lot of GWs of ~ low strength are being modified by such interference, and this will show up as background "noise". One might suspect LISA will be tested with substantial noise, if it ever gets deployed. Of course if a given GW is powerful enough to get through the noise, it can be detected, as has already been done. That is the whole reason for deploying such a large array in space. It was that interference issue that was eating away at me since GWs and the fields that produce them are the most enigmatic physical forces in the universe.
So do you think that the reason gravity in a neutron star is stronger is because we see a lot of constructive interference as matter becomes more compressed?
so one reason may be there are less types of other matter involved we get far less destructive waves of gravity. So more of the gravity escapes the core. Of what was a sun originally, And it likely had far more mass originally?

taking that forward would a set mass of The purest possible diamond have more gravity than a set mass of just random elements?
Even if there set masses were compressed to the same volume.

Could every element On the periodic table have its own wave length of gravity waves.
Like light with its split in colour wave lengths?
It would be interesting to test if true and if you apply pressure, and heat To see if it effects the results. (Pressure and heat equal energy in, in my book). To double check if energy has any effect on gravity.

thanks for your responses so far.

dfjchem721

#### dfjchem721

So do you think that the reason gravity in a neutron star is stronger is because we see a lot of constructive interference as matter becomes more compressed?

A neutron star is a compact object, like planets and stars, so they likely propagate GWs as an average of the "point source". It does not seem there would be variations as you suggest, but I am not an expert.

Simplistically to your post, "energy" is commonly ER, and photons have what is known as energy-mass equivalence. I suspect that is why a black hole will consume photons if they get too close. One concept posits that photons can get too close to a black hole but escape entry, and end up in orbit around it. It is known as a photon sphere. This is certainly a possibility. The photon may stay there indefinitely bound, or at least until (if at all) the BH evaporates to a low enough mass for the photon to escape. All hypotheos here.

Cannot address the rest of your issues without considerable effort. For those areas way outside my expertise, I tend to look at the big picture rather than consider all the fine details of which I have no background, since many of those are often wrong and/or misleading.

It is only when I see people beating their chests (esp. BB aspects) telling us they have it all down with absolute certainty that the digging for details ensues. Find that so comical and arrogant that it requires significant investigation. As I have warned others on such matters, I know enough to be dangerous! How could anyone really believe they know what happened before the BB when they don't even have the whole story of the BB? Simple: They must have jumped to the end of the book and read the final chapter ahead of the rest of us.

Arrogance is one the nastiest aspects of science. Most of the best scientists tend to be modest. They let their science do the talking.

Try wiki for some of your questions. It offers a wealth of information!

Dave643

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