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markusschaber wrote:I had to think a bit about this one, I could not get my mind around it.

Strong gravity is what defines a black hole. At and behind the event horizon, gravity is so strong that it prevents even light from getting out of it.

And black holes don't have a "sharp edge", there is a gravitational funnel arount the event horizon which pulls objects into the funnel, towards the event horizon, just not strong enough to catch light. The strength of the force reduces exponentially with the distance to the center of the gravitation.

And grav sensors detect gravity. Faster than light.

So I just have problems understanding how any black hole, even a very short lived artificial one, should be undetectable by grav sensors.

Particularly, since he is talking about a transient event, so any sensor that is outside of the event horizon is going to see a large apparent mass appear and then disappear. I do not know if this will cause a ripple on the Alpha wall (which is what the gravitic arrays sense), but it will certainly cause a graviton pulse.

tlb wrote:

markusschaber wrote:I had to think a bit about this one, I could not get my mind around it.

Strong gravity is what defines a black hole. At and behind the event horizon, gravity is so strong that it prevents even light from getting out of it.

And black holes don't have a "sharp edge", there is a gravitational funnel arount the event horizon which pulls objects into the funnel, towards the event horizon, just not strong enough to catch light. The strength of the force reduces exponentially with the distance to the center of the gravitation.

And grav sensors detect gravity. Faster than light.

So I just have problems understanding how any black hole, even a very short lived artificial one, should be undetectable by grav sensors.

Particularly, since he is talking about a transient event, so any sensor that is outside of the event horizon is going to see a large apparent mass appear and then disappear. I do not know if this will cause a ripple on the Alpha wall (which is what the gravitic arrays sense), but it will certainly cause a graviton pulse.

There will be no gravity for the grav sensors to detect. Again, black holes are responsible for a phenomena called 'frame dragging' which drags the entire local frame of reference down with it. Local space, and all of the gravity surrounding it (including the gravity on the outside of the black hole) is being dragged inside. Picture a crowded fairgrounds where everyone is moving in one direction and one person is attempting to move against the grain. That is not what is happening. The entire frame of reference is being dragged in. Sensors have to have something to sense. There will not be anything for the sensors to detect.

Graviton pulse??? There is nothing special about a graviton. It has the same speed limit as a photon. It will not escape.

penny wrote:There will be no gravity for the grav sensors to detect. Again, black holes are responsible for a phenomena called 'frame dragging' which drags the entire local frame of reference down with it. Local space, and all of the gravity surrounding it (including the gravity on the outside of the black hole) is being dragged inside. Picture a crowded fairgrounds where everyone is moving in one direction and one person is attempting to move against the grain. That is not what is happening. The entire frame of reference is being dragged in. Sensors have to have something to sense. There will not be anything for the sensors to detect.

Graviton pulse??? There is nothing special about a graviton. It has the same speed limit as a photon. It will not escape.

I agree that a graviton is light speed and I said that I was not sure there was a ripple on the Alpha wave (which is the FTL signal).

Any sufficiently massive object, such as a white dwarf, has frame dragging - see the Wikipedia article.

You are simply wrong if you think that a black hole cannot be detected. The mass is still mass and will have gravitational effects outside of the event horizon. How do you think that NASA could announce the discoveries of probable black holes, if they produced no effects outside of the event horizon? At least one discovery is a binary system where the dark companion is using its gravitation field to steal gas from the normal star companion.

tlb wrote:

penny wrote:There will be no gravity for the grav sensors to detect. Again, black holes are responsible for a phenomena called 'frame dragging' which drags the entire local frame of reference down with it. Local space, and all of the gravity surrounding it (including the gravity on the outside of the black hole) is being dragged inside. Picture a crowded fairgrounds where everyone is moving in one direction and one person is attempting to move against the grain. That is not what is happening. The entire frame of reference is being dragged in. Sensors have to have something to sense. There will not be anything for the sensors to detect.

Graviton pulse??? There is nothing special about a graviton. It has the same speed limit as a photon. It will not escape.

I agree that a graviton is light speed and I said that I was not sure there was a ripple on the Alpha wave (which is the FTL signal).

Any sufficiently massive object, such as a white dwarf, has frame dragging - see the Wikipedia article.

You are simply wrong if you think that a black hole cannot be detected. The mass is still mass and will have gravitational effects outside of the event horizon. How do you think that NASA could announce the discoveries of probable black holes, if they produced no effects outside of the event horizon? At least one discovery is a binary system where the dark companion is using its gravitation field to steal gas from the normal star companion.

I agreed several klicks upstream that it could be detected. Simply not by the system's FTL detector. Remember, I agreed that an avid astronomer could certainly get lucky if he is looking right at it. But a Spider would be long gone before the turnaround time of that type of detection yields fruit. The system would have been already wrecked. Neptune was discovered because of its perturbations on Uranus. But that type of incidental detection is not conducive to system defense. And again, the black hole is only going to last for seconds.

penny wrote:I agreed several klicks upstream that it could be detected. Simply not by the system's FTL detector. Remember, I agreed that an avid astronomer could certainly get lucky if he is looking right at it. But a Spider would be long gone before the turnaround time of that type of detection yields fruit. The system would have been already wrecked. Neptune was discovered because of its perturbations on Uranus. But that type of incidental detection is not conducive to system defense. And again, the black hole is only going to last for seconds.

Note that you specifically said "There will be no gravity for the grav sensors to detect" and I was commenting on that. The FTL signal may not be about gravity exactly, but about the signal traveling on the Alpha wall.

So everything depends on whether this massive perturbation will create ripples on the Alpha wall. You have at times felt that the combined action of the tractor beams (such as when creating this transitory black hole) could affect the Alpha wall.

If you are going to say that it cannot affect the Alpha wall, then it also cannot hide the FTL signal caused by the transition to normal space. Anyway the event horizon stops light speed electromagnetic signals from escaping, but the Alpha wall signal is faster than light speed (so no reason for it to be stopped?).

Interesting (light speed?) things about gravitons, which you said were nothing special. They must not be trapped by the event horizon (or are they created outside the event horizon?), because they can be used to form a binary system with a star and steal gas from it. Also are the Alpha wave ripples graviton pulses traveling at the Alpha band speed?

markusschaber wrote:I had to think a bit about this one, I could not get my mind around it.

Strong gravity is what defines a black hole. At and behind the event horizon, gravity is so strong that it prevents even light from getting out of it.

And black holes don't have a "sharp edge", there is a gravitational funnel arount the event horizon which pulls objects into the funnel, towards the event horizon, just not strong enough to catch light. The strength of the force reduces exponentially with the distance to the center of the gravitation.

And grav sensors detect gravity. Faster than light.

So I just have problems understanding how any black hole, even a very short lived artificial one, should be undetectable by grav sensors.

tlb wrote:Particularly, since he is talking about a transient event, so any sensor that is outside of the event horizon is going to see a large apparent mass appear and then disappear. I do not know if this will cause a ripple on the Alpha wall (which is what the gravitic arrays sense), but it will certainly cause a graviton pulse.

penny wrote:There will be no gravity for the grav sensors to detect. Again, black holes are responsible for a phenomena called 'frame dragging' which drags the entire local frame of reference down with it. Local space, and all of the gravity surrounding it (including the gravity on the outside of the black hole) is being dragged inside. Picture a crowded fairgrounds where everyone is moving in one direction and one person is attempting to move against the grain. That is not what is happening. The entire frame of reference is being dragged in. Sensors have to have something to sense. There will not be anything for the sensors to detect.

Graviton pulse??? There is nothing special about a graviton. It has the same speed limit as a photon. It will not escape.

The "It will not escape" is valid for the event horizon and everything behind it. It's not valid for the space outside of the event horizon, which is still affected heavily by the gravity, but not strong enough for the "nothing will escape".

markusschaber wrote:

markusschaber wrote:I had to think a bit about this one, I could not get my mind around it.

Strong gravity is what defines a black hole. At and behind the event horizon, gravity is so strong that it prevents even light from getting out of it.

And black holes don't have a "sharp edge", there is a gravitational funnel arount the event horizon which pulls objects into the funnel, towards the event horizon, just not strong enough to catch light. The strength of the force reduces exponentially with the distance to the center of the gravitation.

And grav sensors detect gravity. Faster than light.

So I just have problems understanding how any black hole, even a very short lived artificial one, should be undetectable by grav sensors.

tlb wrote:Particularly, since he is talking about a transient event, so any sensor that is outside of the event horizon is going to see a large apparent mass appear and then disappear. I do not know if this will cause a ripple on the Alpha wall (which is what the gravitic arrays sense), but it will certainly cause a graviton pulse.

penny wrote:There will be no gravity for the grav sensors to detect. Again, black holes are responsible for a phenomena called 'frame dragging' which drags the entire local frame of reference down with it. Local space, and all of the gravity surrounding it (including the gravity on the outside of the black hole) is being dragged inside. Picture a crowded fairgrounds where everyone is moving in one direction and one person is attempting to move against the grain. That is not what is happening. The entire frame of reference is being dragged in. Sensors have to have something to sense. There will not be anything for the sensors to detect.

Graviton pulse??? There is nothing special about a graviton. It has the same speed limit as a photon. It will not escape.

The "It will not escape" is valid for the event horizon and everything behind it. It's not valid for the space outside of the event horizon, which is still affected heavily by the gravity, but not strong enough for the "nothing will escape".

It is valid for the frame that is being dragged.

When a black hole forms from imploding gravity, the local frame of reference is being dragged in.

There is some truth in sci-fi -- for instance the movie Event Horizon -- when the Captain tells the navigator not to get too close to the event horizon. There is a danger from getting too close, even though too close is not the same as crossing the event horizon. The grav waves and the light waves that are near -- but on the outside of -- the event horizon are stronger than in "normal space." Therefore a drag is placed upon matter that is too close. If the ship's engines are powerful enough to overcome the currents on the outer perimeter of the maelstrom then no harm no foul.

"Reverse engines."
"We are still being pulled in Captain."
"Full reverse. All power to engines."
"We are breaking free."

The same thing is witnessed at the beach with rip tides. You simply cannot get too close to a rip current if you are a weak swimmer. If you get too close you will be pulled under. *

Rip current speeds as high as 8 feet per second have been measured--faster than an Olympic swimmer can sprint! This makes rip currents especially dangerous to beachgoers as these currents can sweep even the strongest swimmer out to sea.

The difference when it comes to photons and gravitons is that they will also be pulled on by the implosion of the star. Photons and gravity are not sentient. They will not have the motivation or the need to resist being caught in the pull of the mighty beast. In addition, space-time -- the aforementioned frame dragging -- is pulling the very rug (fabric of space) out from under the photons and gravitons.*

*Even if Usain Bolt is fast enough to outrun the effects, he can't because he can't get a grip on the track, the track (space-time) is being pulled out from under him.

All of the rest of gravity and light that is far enough away to be unaffected is insignificant. It is still there as it was before the singularity formed. FTL detectors don't care about the normal grav waves and photons that were there before the singularity. They are innocent bystanders.

markusschaber wrote:The "It will not escape" is valid for the event horizon and everything behind it. It's not valid for the space outside of the event horizon, which is still affected heavily by the gravity, but not strong enough for the "nothing will escape".

penny wrote:
It is valid for the frame that is being dragged.

When a black hole forms from imploding gravity, the local frame of reference is being dragged in.

There is some truth in sci-fi -- for instance the movie Event Horizon -- when the Captain tells the navigator not to get too close to the event horizon. There is a danger from getting too close, even though too close is not the same as crossing the event horizon. The grav waves and the light waves that are near -- but on the outside of -- the event horizon are stronger than in "normal space." Therefore a drag is placed upon matter that is too close. If the ship's engines are powerful enough to overcome the currents on the outer perimeter of the maelstrom then no harm no foul.

"Reverse engines."
"We are still being pulled in Captain."
"Full reverse. All power to engines."
"We are breaking free."

The same thing is witnessed at the beach with rip tides. You simply cannot get too close to a rip current if you are a weak swimmer. If you get too close you will be pulled under. *

Rip current speeds as high as 8 feet per second have been measured--faster than an Olympic swimmer can sprint! This makes rip currents especially dangerous to beachgoers as these currents can sweep even the strongest swimmer out to sea.

The difference when it comes to photons and gravitons is that they will also be pulled on by the implosion of the star. Photons and gravity are not sentient. They will not have the motivation or the need to resist being caught in the pull of the mighty beast. In addition, space-time -- the aforementioned frame dragging -- is pulling the very rug (fabric of space) out from under the photons and gravitons.*

*Even if Usain Bolt is fast enough to outrun the effects, he can't because he can't get a grip on the track, the track (space-time) is being pulled out from under him.

All of the rest of gravity and light that is far enough away to be unaffected is insignificant. It is still there as it was before the singularity formed. FTL detectors don't care about the normal grav waves and photons that were there before the singularity. They are innocent bystanders.

As far as I learned back then in astronomy class, the Event Horizon is exactly the limit of where light and everything else at speed of light cannot escape. That's the very definition of the event horizon.

So outside of the event horizon, things like photons and grav waves can escape.

And there's still a strong gravitation outside of the event horizon (or the ship wouldn't be pullet towards it), just not strong enough from preventing light from escaping. As I wrote above, it's strenght is decreasing with distance. The formula for universal gravitation is F = G * (m1 * m2) / (r^2) with r being the distance between the two centers of the masses.

This also reflects the degree to which the reference frame is dragged in. Light has a constant speed relative to it's reference frame. That means that, outside of the event horizon, the drag on the reference frame is not fast enough to compensate the speed of light. The drag is caused by (and corellated in strength with) gravity, so outside of the event horizon, there is still gravity of the black hole, but the drag is not strong enough to prevent fast enought things from escaping. The bigger the distance, the lower the drag and the lower the gravity.

As far as I found out, there's about 30 million G at the event horizon. So just outside of the event horizon, there's still a small area with millions of G, and a bigger area with thousands of g, until it gradually fades out. That should be quite measurable by grav sensors.

tlb wrote:Particularly, since he is talking about a transient event, so any sensor that is outside of the event horizon is going to see a large apparent mass appear and then disappear. I do not know if this will cause a ripple on the Alpha wall (which is what the gravitic arrays sense), but it will certainly cause a graviton pulse.

I don't know about the Alpha wall, but if such a thing happened in our universe, it would generate a gravity wave of the kind we have been detecting for the past 7 years. This is the same way as a charge appearing and disappearing creates a propagating electric field, something we've known for 150 years now as "electromagnetic radiation." And if you made a magnetic monopole and unmade it, it would also create a spherical magnetic field.

penny wrote:There will be no gravity for the grav sensors to detect. Again, black holes are responsible for a phenomena called 'frame dragging' which drags the entire local frame of reference down with it. Local space, and all of the gravity surrounding it (including the gravity on the outside of the black hole) is being dragged inside. Picture a crowded fairgrounds where everyone is moving in one direction and one person is attempting to move against the grain. That is not what is happening. The entire frame of reference is being dragged in. Sensors have to have something to sense. There will not be anything for the sensors to detect.

That's not how black holes or gravity work.

Black holes have three properties: mass, charge, and spin. The mass is what defines it as a black hole and creates the event horizon. The charge doesn't matter really because a charged black hole will attract the opposite charge and neutralise itself quickly. The spin is what creates he frame dragging.

But all of those three properties "escape" the black hole because they are not inside of it. The mass and the frame-dragging are a property of the local region of space-time itself.

Yes, frame-dragging can be similar to standing on a merry-go-round, where you're not moving relative to local space but space is. But the merry-go-round going around does not make the merry-go-round disappear. Parents would have been horrified if that happened!

Graviton pulse??? There is nothing special about a graviton. It has the same speed limit as a photon. It will not escape.

Gravity "escapes" a black hole. That's how we know it is there.