...something we already know about completely.

I've never been so conceded as to assume I know -- or will know -- about any topic "completely". Regardless of topic, though, that is always my ultimate, unapproachable goal.

Even in areas where I consider myself an expert, I still learn new things every day.

The inability to gain total knowledge is never an excuse not to pursue it.

 

The inability to gain total knowledge is never an excuse not to pursue it.

Would you mind if I have that last phrase of yours printed in gold letters and framed? ... kudos to you, my friend, for your excellent attitude

 

I've never been so conceded as to assume I know -- or will know -- about any topic "completely". Regardless of topic, though, that is always my ultimate, unapproachable goal.

Even in areas where I consider myself an expert, I still learn new things every day.

The inability to gain total knowledge is never an excuse not to pursue it.

Hi,

Yes i agree with that last statement, but there are also logical statements that show that we are limited in what we CAN know no matter how hard we try. It's not that we dont want to know it's that we can not know it even if we pursue with all effort because there is logical proof that we cant. That was my goal here...to show that maybe we cant.

As to analogies, i mean the type we use to explain things. So we assume we know something and then use it to explain something else. It's all we can do really.
For example, maybe a bad one though, the water current analogy. We sometimes say that current in a wire is like water through a pipe. Yeah it is not exactly, it's an analogy. We can come up with better analogies and even better ones after that, but once we reach a circuit point we seem to get lost. We can not have current 'flow' in a wire if we have no time for it to flow in. dQ/dt requires time, and with no time there is no derivative.

Another analogy is if time goes to zero, we are effectively dead. We cant move, we cant breath, we cant interact with other humans. Yeah sure, if for some reason time could start up again then we would be alive again, but if it never starts up again, we are effectively dead ... preserved ... for all eternity. Unfortunately that means we can not learn anything new either.

So to the point of the thread, if we were living inside a black hole we could not be alive in the normal sense of what we think of as being alive. But a side point is that since we cant even ask the proverbial "if a tree falls" question, we certainly cant answer it. In other words, our experience breaks down so far that we cant deal with it because we have no way to deal with zero time.

I hope i have shed some light on my point of view. The intent was to show that we may never know some things about black holes, as well as try to show more proof that we are not living inside one.

Another possibility is that gravity and time are so intertwined that the fact that we have gravity less than infinite means we are allowed to live, to carry on our lives. So extending the definition of a super massive black hole, we live near one, close enough to have some gravity but not infinite. So in that sense we live inside the region of influence of the black hole, but if we get too close to the center we cease to exist and physical theories cease to be effective in figuring things out.

 

Hi,
It seems to me that we can not fully comprehend a black hole in the first place. That's because our comprehension, our existence depends on time itself. If we have zero time, we have zero comprehension. If we have zero time to exist we have zero comprehension.

I'm not sure where you get zero time. To a far-away observer, a clock falling into a black hole appears to continuously slow down, but to an observer falling with the clock, time runs normally. In both cases time continues to tick.

While it's true that worldlines within the event horizon end at the singularity (which represents a tomorrow that never comes), the singularity is not actually a part of the physics -- it's where the physics breaks down. Personally, I'm hopeful that with an effective theory of quantum gravity we'll be able to comprehend what happens inside a black hole.

 

I'm not sure where you get zero time. To a far-away observer, a clock falling into a black hole appears to continuously slow down, but to an observer falling with the clock, time runs normally. In both cases time continues to tick.

While it's true that worldlines within the event horizon end at the singularity (which represents a tomorrow that never comes), the singularity is not actually a part of the physics -- it's where the physics breaks down. Personally, I'm hopeful that with an effective theory of quantum gravity we'll be able to comprehend what happens inside a black hole.

Hi,

Yeah that's what i am saying, that the physics breaks down and i am giving at least one reason for that. So i am not JUST saying that the "physics breaks down", i am giving a good reason for that....that's really my whole point.
Obviously i am talking about the very center not at distances from the center.

But perhaps you are saying that we could still be living in a black hole, just not at the center. Yes i agree with that to some extent (not much though), because we would not know if our time was already slowed down. I think there may be a way to measure this though. In fact it may show up in older experiments. That is because certain behaviors would not be isotropic and so we would see changes depending on which direction we looked in. After all, we would be heading toward the center and so for one example gravity on one end of the universe would be stronger than on the other end. As far as i know, this is not the case. This makes it doubtful that we are living anywhere in a black hole.

As to the black hole itself, quantum spacetime would be my preference.

 

But perhaps you are saying that we could still be living in a black hole, just not at the center.

For the record, I definitely do not believe that we're living in a black hole. See my argument from thermodynamics in this thread -- black holes contain the maximum entropy for a given volume, and we clearly do not live in a maximum entropy universe (we can do work).

 

But perhaps you are saying that we could still be living in a black hole, just not at the center.

I believe there is a "center" of a black hole (with respect to an observer inside the event horizon) in the same way there is a "center" of our universe. IOW, there is none...everything looks exactly the same in every direction regardless of your position.

 

I believe there is a "center" of a black hole (with respect to an observer inside the event horizon) in the same way there is a "center" of our universe. IOW, there is none...everything looks exactly the same in every direction regardless of your position.

Hi,

That just cant be true. As we get closer to the singularity, gravity gets stronger. That means there is a gravity gradient. That leads to the so called spaghettification. I dont see any of that behavior anywhere in the universe today.

 

That leads to the so called spaghettification.

This is a function of tidal forces, and the effect is stronger for small black holes.

For much larger black holes, space would appear "normal" to an infalling observer, even after having fallen past the event horizon.

Now, if you can tell me you are certain what happens to that observer, I am going to ask you to prove it.

 

This is a function of tidal forces, and the effect is stronger for small black holes.

For much larger black holes, space would appear "normal" to an infalling observer, even after having fallen past the event horizon.

Now, if you can tell me you are certain what happens to that observer, I am going to ask you to prove it.

I could prove it ... but then I'd have to bring Matthew McConaughey into the discussion ... jokes aside, I loved the speculative science of that movie, I even bought a book written by one of the scientific consultants.

 

This is a function of tidal forces, and the effect is stronger for small black holes.

For much larger black holes, space would appear "normal" to an infalling observer, even after having fallen past the event horizon.

Now, if you can tell me you are certain what happens to that observer, I am going to ask you to prove it.

Hi,

You are saying that in a very large black hole the gradient is minimal at some places.
That's fine i guess, but then it would have to be MUCH MUCH MUCH larger than the whole universe. So if you want something proved, prove that.

But to think about what mimimal gradient it would take to make the universe appear as it does today, i have trouble believing that the gradient over such a huge, huge distance (one end to the other or across or whatever) would show SOME directional effect. What i see is not what we believe happens inside a black hole...we see things flying outward in all directions.

This thread is mostly speculation anyway so i doubt you will see anything actually proved. We all throw our thoughts and opinions into the melting pot and see what boils out. I try to keep in mind though that although ANYTHING is possible, not EVERYTHING is reasonable. That's all we have to go on or else we might as well not talk at all.

 

I think all stars have a dark side. They give off light and build larger elements....but they also break down a lot of H(dipoles) and excrete large amounts of isolated charge. These charges are not effected by gravity. As far as we can tell, there are still under acceleration out past Neptune.

Think of all the shinning stars thru time. Heck, 90% of the universe might be free charge. It might be very dark out there compared to earlier times. Gravity might have been much greater than the past.

When the gravitational force decreases, the orbits expand. If the decrease was fast and sharp......it would have been like an kick acceleration.

OR, Maybe 1000 or so times out from Neptune.....the Oorc Cloud...this charge might re-unite in a cold way. It might give us a omni direction CMB.

Who really knows?

 

I could prove it ... but then I'd have to bring Matthew McConaughey into the discussion ... jokes aside, I loved the speculative science of that movie, I even bought a book written by one of the scientific consultants.

He died the moment he ejected. The entire tessaract scene was a death dream about his children.

 

but then it would have to be MUCH MUCH MUCH larger than the whole universe.

Here's some pop science for you:

However, if you're dead-set on visiting a space-time singularity, we recommend going big; bigger black holes have less extreme surfaces. "If you had a black hole the size of our solar system, then the tidal forces at the event horizon … are not quite that strong. So you could actually maintain your structural integrity," Liu said.

 

Here's some pop science for you:

In fact, from the same article:

So if you're able to look forward toward the black hole, you see every object that has fallen into it in the past. And then if you look backwards, you'll be able to see everything that will ever fall into the black hole behind you.

This, I believe is a (slight) misinterpretation of Eddington–Finkelstein solution -- but it is what I mean when I ask the question:

You fall past the event horizon of a black hole and look up. What do you see?

 

In fact, from the same article:



This, I believe is a misinterpretation of Eddington–Finkelstein solution -- but it is what I mean when I ask the question:

You fall past the event horizon of a black hole and look up. What do you see?

So, how can everything, from the entirety of the past to the entirety of the future, fit in something that is not the size of a universe. And if it is the size of a universe, why can we not just call it a universe?

 

You fall past the event horizon of a black hole and look up. What do you see?

My understanding is that within the event horizon, all light cones point to the singularity, i.e., toward r = 0. An observer free-falling toward the singularity wouldn't see anything in front of him, as all light would be falling with him. He certainly wouldn't see every object that has fallen before him -- that would require the light to travel away from the singularity.

If the free-falling observer faced backward, he'd probably see a diminishing disc of of light that eventually became a point and then disappeared. This would happen really fast, so there's no reason to believe that he'd see "everything that will ever fall into the black hole". If he could somehow hover inside the black hole, avoiding the singularity, the light coming in behind him would be greatly blue-shifted. The resulting gamma radiation would fry him well before he noticed much of anything.

 

...as all light would be falling with him.

I don't believe for a second that GR breaks down for an observer free-falling through the event horizon.

 

I don't believe for a second that GR breaks down for an observer free-falling through the event horizon.

Neither do I. GR itself tells us that the singularity is in the future of every light cone within the event horizon. Anything free-falling through a black hole rides a geodesic straight to the singularity.

 

Anything free-falling through a black hole rides a geodesic straight to the singularity.

There is no singularity. Just a 2D event horizon upon which the entire history of the black hole is irretrievably imprinted.

My theory: the 2D surface inflates into 3D as an object crosses (actually, enters into, it).