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Big disclaimer: I'm not a physicist. Those who know better should feel free to correct inaccuracies.
The difference is the reference frame. On the planet you feel the planet's gravity, you don't feel the black hole's gravity because you're in orbit around it, even though you're definitely influenced by it. The time dilation is caused by the black hole's massive gravity distorting spacetime in its surrounding area relative to other things, so the planet's gravity really has nothing to do with it.
Think of it this way - if I'm in a car moving at 100kph in the direction the earth is spinning. Technically from the perspective of someone standing still relative to the earth I'm actually moving at the speed of earth's rotation + 100kph. That's a little under mach 2, but to the person in the car it doesn't feel that way because these forces are constant. You are technically in a consistent freefall. along with the earth.
Yes, but the issue here is why would the time dil;ation on the surface be so vastly different to the orbiting spacecraft? They are both within the almost the same gravitation as related to the blackhole.
Are you saying that the surface experience of blackholeG+1.3G gives you this much time dilation compared to the orbiting spacecraft's blackholeG?
No, I'm saying you're within the planet's reference frame, and the gravity of the black hole is consistent. According to the article, the orbiting spacecraft isn't as close as you think it is, and is assumed to be in a high orbit. Keep in mind that the effects of gravity are directly related to the mass of the objects that are interacting. As Newton's Law of Universal Gravitation states:
Any two bodies in the universe attract each other with a force that is directly proportional to the product of their masses and inversely proportional to the square of the distance between them.
This means that not only is gravitational strength lessened by the size of the interacting objects decreasing, it's also lessened dramatically by the distance between the objects. As a result, the gravitational effect on the planet is much greater than the gravitational effect on the ship. The closer you move to the black hole, the deeper the spacetime "well" is, and the more prominent the dilation effects are. In this instance, it helps a great deal to understand what inverse-square law is.
Another force which follows this law is magnetism. It has an exponentially weaker force the further two magnets are from each other. However as they approach, the force gets exponentially stronger.
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[–] SkepticalMartian [S] ago (edited ago)
Big disclaimer: I'm not a physicist. Those who know better should feel free to correct inaccuracies.
The difference is the reference frame. On the planet you feel the planet's gravity, you don't feel the black hole's gravity because you're in orbit around it, even though you're definitely influenced by it. The time dilation is caused by the black hole's massive gravity distorting spacetime in its surrounding area relative to other things, so the planet's gravity really has nothing to do with it.
Think of it this way - if I'm in a car moving at 100kph in the direction the earth is spinning. Technically from the perspective of someone standing still relative to the earth I'm actually moving at the speed of earth's rotation + 100kph. That's a little under mach 2, but to the person in the car it doesn't feel that way because these forces are constant. You are technically in a consistent freefall. along with the earth.
[–] fgutrfgu ago
Yes, but the issue here is why would the time dil;ation on the surface be so vastly different to the orbiting spacecraft? They are both within the almost the same gravitation as related to the blackhole.
Are you saying that the surface experience of blackholeG+1.3G gives you this much time dilation compared to the orbiting spacecraft's blackholeG?
[–] SkepticalMartian [S] ago (edited ago)
No, I'm saying you're within the planet's reference frame, and the gravity of the black hole is consistent. According to the article, the orbiting spacecraft isn't as close as you think it is, and is assumed to be in a high orbit. Keep in mind that the effects of gravity are directly related to the mass of the objects that are interacting. As Newton's Law of Universal Gravitation states:
This means that not only is gravitational strength lessened by the size of the interacting objects decreasing, it's also lessened dramatically by the distance between the objects. As a result, the gravitational effect on the planet is much greater than the gravitational effect on the ship. The closer you move to the black hole, the deeper the spacetime "well" is, and the more prominent the dilation effects are. In this instance, it helps a great deal to understand what inverse-square law is.
Another force which follows this law is magnetism. It has an exponentially weaker force the further two magnets are from each other. However as they approach, the force gets exponentially stronger.