Particles going backwards in time within the event horizon.

If the escape velocity is greater than the speed of light within the
event horizon of a black hole, shouldn't particles trapped within the
event horizon be going backwards in time?

Dear Zanthius:

On Apr 4, 11:51*am, Zanthius wrote:
If the escape velocity is greater than the speed
of light within the event horizon of a black hole,
shouldn't particles trapped within the event
horizon be going backwards in time?

No.

It just means there are no possible velocity vectors for light or
massive particles that point out of the event horizon.

David A. Smith

On Apr 4, 9:51*pm, dlzc wrote:
It just means there are no possible velocity vectors for light or
massive particles that point out of the event horizon.

David A. Smith

Shouldn't particles within the event horizon behave just like tachyons
as they are subjected to an escape velocity that is greater than the
speed of light?

Tachyons have a velocity that is greater than the speed of light, and
they are supposed to go back in time.

Dear Zanthius:

On Apr 4, 1:09*pm, Zanthius wrote:
On Apr 4, 9:51*pm, dlzc wrote:

It just means there are no possible velocity
vectors for light or massive particles that point
out of the event horizon.

Shouldn't particles within the event horizon behave
just like tachyons as they are subjected to an
escape velocity that is greater than the speed of
light?

No. "Subjected to escape velocity" is meaningless. We who are
outside a black hole show way too much hubris about what *must* be
happening inside. If we turn around and look at the CMBR, maybe that
is what the infallers "must" see...

Tachyons have a velocity that is greater than the
speed of light, and they are supposed to go back
in time.

No, they don't. Their minimum speed is c, and they are "expected" to
experience *forward* time.

David A. Smith

Zanthius wrote:
If the escape velocity is greater than the speed of light within the
event horizon of a black hole, shouldn't particles trapped within the
event horizon be going backwards in time?

The maximum speed of the particles is still c. Escape velocity simply
means the minimum velocity required to escape that region. That doesn't
mean that the particles in that region actually have to be travelling at
that speed.

The escape velocity on the surface of the Earth is 40,000 km/h or 25,000
mph. We're objects on the surface of the Earth, and we're not running
around at just below 25,000 mph here, we're running around at a lot
below that speed.

Yousuf Khan

On Apr 5, 6:41*am, Yousuf Khan wrote:
The maximum speed of the particles is still c. Escape velocity simply
means the minimum velocity required to escape that region. That doesn't
mean that the particles in that region actually have to be travelling at
that speed.

I don't care about the speed of the particle. I am interested in how
gravitational time dilation is related to time dilation in special
relativity. If gravitational time dilation outside of the event
horizon correlates to time dilation at subluminal speeds, and time
dilation at the event horizon is equal to time dilation at lightspeed,
then time dilation within the event horizon should correlate to time
dilation at superluminal speeds.

On Apr 5, 2:27*am, dlzc wrote:
No, they don't. *Their minimum speed is c, and they are "expected" to
experience *forward* time.

Not according to wikipedia:

http://en.wikipedia.org/wiki/Time_tr...n-light_travel

Zanthius wrote:
On Apr 5, 6:41 am, Yousuf Khan wrote:
The maximum speed of the particles is still c. Escape velocity simply
means the minimum velocity required to escape that region. That doesn't
mean that the particles in that region actually have to be travelling at
that speed.

I don't care about the speed of the particle. I am interested in how
gravitational time dilation is related to time dilation in special
relativity. If gravitational time dilation outside of the event
horizon correlates to time dilation at subluminal speeds, and time
dilation at the event horizon is equal to time dilation at lightspeed,
then time dilation within the event horizon should correlate to time
dilation at superluminal speeds.

Both time dilations are the same thing. But that's irrelevant. The point
is that even if the escape velocity of objects under the event horizon
are greater than the speed of light, that doesn't mean that the objects
in that region are actually travelling faster than that. The escape
velocity is simply a measurement of the force of gravity in the region.

Yousuf Khan

On Apr 5, 1:52*am, Zanthius wrote:
On Apr 5, wrote:

No, they don't. *Their minimum speed is c, and they
are "expected" to experience *forward* time.

Not according to wikipedia:

If you use up the "mathemagic" of an imaginary number in getting FTL,
then there is nothing left over to do "inverted time". Tachyons are
*not* normal matter.

If you (could) take normal matter FTL, then you would naively expect
it to experience reverse time.

Wackypedia is not a good source.

David A. Smith

Dear Zanthius:

On Apr 5, 1:49*am, Zanthius wrote:
On Apr 5, 6:41*am, Yousuf Khan wrote:

The maximum speed of the particles is still c. Escape
velocity simply means the minimum velocity required
to escape that region. That doesn't mean that the
particles in that region actually have to be travelling at
that speed.

Let's add that infallers would still measure c for the speed of light
locally, regardless of direction (again as determined locally).

I don't care about the speed of the particle. I am
interested in how gravitational time dilation

.... part of GR ...

is related to time dilation in special relativity.

They aren't strongly related. Which is why GR had to be invented.

If gravitational time dilation outside of the event
horizon correlates to time dilation at subluminal
speeds,

It doesn't.

and time dilation at the event horizon is equal to
time dilation at lightspeed,

It isn't. A body at *rest* at the event horizon might achieve such...
but no finite amount of thrust could keep an object there.

then time dilation within the event horizon should
correlate to time dilation at superluminal speeds.

You apparently missed my point about hubris, and us flatlanders
telling Nature what Nature "should" do. We may be inside a black hole
now. Look back at the past that is displayed and tell us what Nature
is then telling us about the inside of a black hole.

David A. Smith