The Orville Season Two - Thoughts?

Umbran · May 15, 2019

I finally got around to watching the final episode.

It was like someone in the writer's room said, "Hey, waitaminute. We are a Trek homage show. If we haven't made science-literate geeks have at least one moment of abject apoplexy this season, we aren't doing our job!"

Other than my speachless gesticulating at the screen for a few moments, it was decent.

Umbran · May 15, 2019

Kaodi said:
But the fact that they can "see" what is going on inside the black hole is super dumb: if their sensors can accomplish that inside the black hole they should be able to accomplish it outside.

Nope. That part is pretty much okay. Light falling in to a black hole does not *stop* at the event horizon. It falls in, and could be detected on the inside. Okay, technically it gets blue-shifted to gamma rays on the way in, but that's the *least* of the problems with the black hole bit.

Richards said:
The fact that they made such a point about the intense pressure under seven miles of ocean made ignoring the pressure from inside a black hole even that much more painful to stomach.

There isn't any particular pressure inside a black hole. It is still a vacuum, for one thing. And the space inside the event horizon is just like the space outside it. The curvature increases as you head toward the singularity, but there's no discontinuity at the event horizon that suddenly increases pressure.

Kaodi · May 15, 2019

Umbran said:
Nope. That part is pretty much okay. Light falling in to a black hole does not *stop* at the event horizon. It falls in, and could be detected on the inside. Okay, technically it gets blue-shifted to gamma rays on the way in, but that's the *least* of the problems with the black hole bit.

This does not quite make sense to me. For them to "detect" the light falling towards the centre some would still have to escape towards them, would it not? But the "event horizon" should not really be a singular place, should it? Once you are inside it is basically event horizons all the way down, is it not? If light cannot escape at x distance then there is no way it can escape at x - n distance.

Nagol · May 15, 2019

Umbran said:
Nope. That part is pretty much okay. Light falling in to a black hole does not *stop* at the event horizon. It falls in, and could be detected on the inside. Okay, technically it gets blue-shifted to gamma rays on the way in, but that's the *least* of the problems with the black hole bit.

There isn't any particular pressure inside a black hole. It is still a vacuum, for one thing. And the space inside the event horizon is just like the space outside it. The curvature increases as you head toward the singularity, but there's no discontinuity at the event horizon that suddenly increases pressure.

There would be tidal stress effects on the hull though, but that would be "pushing out" (actually linear stretching stress as opposed to expansion) as opposed to "pressing in". The ship needs to be designed to support a minimal amount of analogous "pushing out" from air pressure so I could wink at external pressure being a greater risk. It just has to be a *very* big black hole to drop the tidal effect to manageable levels. Who knew a massive black hole was wandering around that section of the galaxy? No one! No one knew!

Nagol · May 15, 2019

Kaodi said:
This does not quite make sense to me. For them to "detect" the light falling towards the centre some would still have to escape towards them, would it not? But the "event horizon" should not really be a singular place, should it? Once you are inside it is basically event horizons all the way down, is it not? If light cannot escape at x distance then there is no way it can escape at x - n distance.

It's not escaping towards them, they are inside the event horizon so light is falling over them like water in a shower on its way deeper into the hole. The event horizon is the surface of a sphere some distance from the singularity point (the more massive the hole, the farther the surface of the sphere from centre of mass). Nothing is really there other than gravity at sufficient force levels that light can't escape.

tomBitonti · May 15, 2019

If they are inside the black hole, then either they are using their faster-than-light drive to keep from falling inwards, or they are falling inwards along with light any any other unlucky matter in their vicinity. (Light would be moving along a geodesic which terminates at the singularity; any normal motion must also terminate at the singularity.)

Just *keeping still*, meaning, keeping at a constant distance from the singularity, requires use of the faster-than-light drive.

In regards to tidal forces, to tell whether the ship and crew are "spaghettified" this: https://en.wikipedia.org/wiki/Spaghettification suggests the following values:

(Solar masses, event horizon radius, "spaghettification" radius")
(10 S, 30 km, 320 km)
(100 S, 300 km, 685 km)
(1000 S, 3000 km, 1462 km)
(10000 S, 30000 km, 3200 km)

The critical radius moves inside of the event horizon somewhere between 100 and 1000 solar masses.

Thx!
TomB

Umbran · May 15, 2019

Nagol said:
It just has to be a *very* big black hole to drop the tidal effect to manageable levels. Who knew a massive black hole was wandering around that section of the galaxy? No one! No one knew!

Oh, their handling of the tidal forces can be explained - we know they can generate gravity (to keep people with feet on the deck, and probably more dynamically to keep crew members from becoming red smears on the bulkheads when they perform high acceleration maneuvers). They just use internal gravity generators to counter the effects.

Umbran · May 15, 2019

tomBitonti said:
If they are inside the black hole, then either they are using their faster-than-light drive to keep from falling inwards, or they are falling inwards along with light any any other unlucky matter in their vicinity. (Light would be moving along a geodesic which terminates at the singularity; any normal motion must also terminate at the singularity.)

Just *keeping still*, meaning, keeping at a constant distance from the singularity, requires use of the faster-than-light drive.

Yep. And, a nod to this would have been a really good way to prevent us from awkwardly gesticulating at the TV in frustration

Umbran · May 15, 2019

Kaodi said:
This does not quite make sense to me. For them to "detect" the light falling towards the centre some would still have to escape towards them, would it not?

Nope.

They are just inside the event horizon, looking out. Photons from outside are falling in at them - they can detect those. There will be some warping of the field of view, but the event horizon does not present a discontinuity. If you are just outside the event horizon, looking around, and then step just inside, the world will look much the same.

But the "event horizon" should not really be a singular place, should it? Once you are inside it is basically event horizons all the way down, is it not? If light cannot escape at x distance then there is no way it can escape at x - n distance.

Pretty much, yes. The event horizon is the *outermost* such position. Which means you can always see things that are farther out from the singularity than you are. You can't look *inwards* and see anything. You always seem to be standing on the surface of a black sphere.

tomBitonti · May 16, 2019

Umbran said:
Nope.

They are just inside the event horizon, looking out. Photons from outside are falling in at them - they can detect those. There will be some warping of the field of view, but the event horizon does not present a discontinuity. If you are just outside the event horizon, looking around, and then step just inside, the world will look much the same.

Pretty much, yes. The event horizon is the *outermost* such position. Which means you can always see things that are farther out from the singularity than you are. You can't look *inwards* and see anything. You always seem to be standing on the surface of a black sphere.

Is this correct? If one were held still, perhaps, but an infalling observer should still see objects which fell ahead of them. In the infalling frame, the light proceeds outwards. From the perspective of a still frame of reference, the observer would seem to catch up to light emitted by the object which preceded them across the event horizon.

If objects which fell ahead of the observer could not be seen, then physics as we know it would not occur for the observer once they are within the event horizon: Putting the observer's feet closer to the singularity, no nerve signal could be transmitted to reach the observer's brain. Putting the floor beneath the observer's feet closer to the singularity than the observer's feet, no exchange particles could reach outwards from the floor to create contact pressure. I am thinking, all sorts of physical processes would be very different. That is not consistent with the idea that the event horizon could be crossed without notice (aside from tidal effects).

Thx!
TomB