• We’re currently investigating an issue related to the forum theme and styling that is impacting page layout and visual formatting. The problem has been identified, and we are actively working on a resolution. There is no impact to user data or functionality, this is strictly a front-end display issue. We’ll post an update once the fix has been deployed. Thanks for your patience while we get this sorted.

Relatively simple question

S

Smilin

Diamond Member
Imagine you and say 1-10 other people jumping into a black hole. Not all at the same time, but generally one after another. Sometimes two people may jump in side by side. Assume for some reason you can all survive this experience until the moment you hit the event horizon.

From your perspective what would happen to the people going in before during and after you? Specifically, how would time and distance behave?
 
from your perspective, the people who jumped before you will still be before you and those who jumped behind you will still be behind you.... the sequence of happenings wouldn't change... but distance might be varied between each jumper/s depending on how long it takes to get to the event horizon(if its possible to actually reach it instad of infinatly approaching it), so those who jumped a second ahead of you from your perspective, might be 10000x closer to you than those who jumped two seconds AFTER you jump.

i'm probably totally wrong in all the above, but thats how i envision it....
 
In newtonian physics the people before and after you would get progressively further away. Each one would be accelerating at a different rate with the people in the back the slowest.

Time would appear perfectly normal to each observer but time would be slowing down as they fell in. I think to the first person in would seem to take forever to reach the event horizon from their point of view but it would happen to them quickly from observers further behind.

What I'm really getting at is an answer to a different question. I have this idea and it would boggle my mind if it's true, so I'm hoping someone can shoot some holes in it for me. The idea is this:

I think our idea of an expanding universe may be backwards.

Our current observations indicate the universe is expanding at an accelerating rate. Everything we see around us is red shifted and moving away from us. Things further away are moving away even faster. From our point of view everything is moving away from us at an accelerating rate. The models attempting to explain this are getting more and more complicated. If we have it backwards it would explain our observations fully and in a simple manner. The universe is not expanding away from a singularity in our past, it is falling into a singularity in our future.

I need someone to explain to me how this can be wrong.


edti: splelling
 
Objects on the other side of the singularity would appear to be blue shifted. So we would need to look for a blue shifted area at the very edge of the universe, as of yet the further back we look in any direction the greater the red shift.
 
Originally posted by: Smilin
Would objects on the other side of the singularity even be visible?
Click to expand...

Yes, provided they are outside the event horizon. Also, someone above mentioned something about time approaching the event horizon. It wouldn't seem like an infinite amount of time. Perhaps you're thinking of approaching the singularity? Nonetheless, as you accelerated, even if you accelerated to a speed close to the speed of light, then to you, it would seem like a very very short amount of time, due to time dilation. For an observer at a distance in a "stationary" frame of reference, it would seem like more time.
 
You wouldn't neccessarily need exactly opposite, just 90 degrees away from us would surely be visible and blue shifted.
 
I took a class in relativity like 4 years ago when I was an undergrad, and I forgot most of it. It's true that as you're falling into a black hole there would be differences in acceleration. A black hole's gravity is so insanely huge that tiny changes in distance still translate to large changes in acceleration. You would get pulled apart (i.e. your feet would get yanked off, etc. . )

This sounds a lot like that Lorentz transformation question where someone asked "What would happen if I were sitting on a train that was approaching the speed of light and I shined a flashlight forward?" a little info here I can't quite remember all the stuff that goes on as you approach a black hole. I might have to go dig out my old notebook and see if we talked about what happens to the frame of reference of the observer falling into a black hole from infinite distance. We probably did and I'm just too stupid to remember it. There's a certain point you reach where photons are stuck in orbit around the black hole and you'd see the back of your own head. That's pretty cool.

But yeah, once you cross the event horizon, all bets are off. Your time and position coordinates trade places and I don't even know what that would look like. I think I'll go hunting for my notebook, you got me all curious now.
 
So do you think it is possible the universe could be falling into a singularity rather than expanding out from one? Does it match known observations? Is there some 'gotcha' here that blows this idea out of the water?

thanks
 
Unless I?ve missed something, all replies to this thread concern black holes hat are not rotating. I may be mistaken, but I believe all stars rotate. When collapsing into a black hole, a star must maintain its angular momentum and in doing so the rotational velocity would be very great, probable in the order of hundreds of RPM?s. The consequence of that would cause the event horizon and the physical boundary of the black hole to be the same at the polar regions, and the event horizon a much greater diameter at the equatorial regions. If one watches someone fall toward a black hole, that person would be dragged along by the holes rotation and begin a long spiraling path towards the event horizon. His velocity would eventually be a good fraction of the speed of light as he whizzes past the observer many times while spiraling inward. At some time he will enter the region where photons are in orbit around the black hole and just outside the event horizon. This region will be very bright, so it is unlikely the person would be visible amid the brilliance of the background. If he could be seen, just before he reaches the event horizon, he will seem to be frozen in orbit and will be visible forever. Space-time, just outside the event horizon, is so distorted seconds will appear as eons to the distant observer. Actually, the person could not be seen as the photons reflected from his body would be so red-shifted by the gravitational force, they will be well within the radio spectrum. You might say he could be heard but not seen.

If one observes an object that is behind the black hole, the photons from that object will acquire energy from the black hole as they move toward it and will be blue shifted. As they pass the hole, they may be sucked in, go into orbit, or lose energy as they pass by. In losing energy, they will be red-shifted. Recall that a photon, unlike a particle having mass, cannot be accelerated or de-accelerated, it always must travel at the speed of light. It can only lose or gain energy.

Due to the black-holes rotation, it?s been mathematically shown that if a star collapses into a black hole it will not be a sphere, but a ring (toroidal) shaped object. It allows the possibility of passing through the center (wormhole).

In regards to the universe not expanding, but collapsing into a singularity: Just the fact that all light from objects at cosmic distances is red-shifted belies that theory.
 
In regards to the universe not expanding, but collapsing into a singularity: Just the fact that all light from objects at cosmic distances is red-shifted belies that theory.
Click to expand...

Why so?
 
BTW if you're really into this stuff (and it sounds like you are) You might wanna check out HyperSpace by Michio Kaku. The guy is a goddamn genius and does a damn good job of explaining theoretical physics to a relatively lay person. I read it and it blew my f%#king mind. Twice.

Also, just about anything by Kip Thorne it really good. They're both goddamn geniuses.
 
Smilin ? It would be easier to reply if you raised specific points. In regards to the red-shift as a good indicator of the expanding universe:

There is a class of stars called Cepheid variables. They behave in a well-known fashion and seem to be present in all galaxies where individual, moderately bright stars can be discerned. As we observe the distant galaxies and analyze the spectrum of the Cepheid?s, we find the spectrum to be red-shifted proportional to their distance from us. By red shift, it is meant that the photons wavelength is longer now than when it was first emitted by the star. The most plausible reason for that is that space has expanded. If the universe were contracting, there would necessarily be a blue shift. That has never been observed except as a localized Doppler effect.

Since individual normal type stars are not visible in far distance galaxies, Type A Super Nova stars are now used to determine the degree of red shift in those far away galaxies. As I mentioned in a previous thread, these observations not only indicate an expanding universe, but that the expansion is accelerating.
 
I understand red shift/blue shift. I also understand that since Hubble we have understood that stars are red shifted (implying they are moving away). I also know that things further away appear to further red shift. Basically I know our current observations show that the universe is expanding and that stars further from us are expanding faster. The thing that is throwing a wrench at physicists right now is they cannot explain why the expansion is *accelerating*. The model is getting more and more complicated as we try to explain these new observations. What if the model is simply wrong?

What I'm saying is that our observation of red shifted objects can also be explained by the universe collapsing at an accelerating rate. Drop a singularity "out there" somewhere. Put it beyond the edge of the currently observable universe but not neccessarily at an infinite distance. Now imagine the universe falling into it. We will fall into it and stars closer will be falling faster and appear red shifted. Stars further away will also be falling in but not as quickly as us. With the relative motion they will also appear red shifted. In fact the further any star is from us the faster it will appear to be moving away from us. This corresponds to the observations that we are currently interpreting as expanding. The only difference is this model accounts for the acceleration of the observed expansion.

I'm surely not the only person who's ever thought of this. Since it's not accepted as a current model of the universe I can only assume there is some hole in my logic that I'm missing. I figured the guys here would be the best ones to politely put me in my place. So, please do so and thanks in advance! 🙂


Polishwonder: I'll check out that Michio Kaku book. I've read some Kip Thorne, Stephen Hawking and also a book they did together.


Edit: Another way to say it... The universe is not expanding but it is getting "stretched" as it collapses towards a singularity.
 
Smilin ? I think I now understand your reasoning and off hand it seems it can account for only galaxies lying on a straight line with us. Galaxies on the other side of the singularity would be accelerating towards us and be blue shifted. If the singularity were at the edge of the universe, depending on a galaxies angle of approach and distance, we would see varying degrees of red or blue shifting. Stars the same distance from the singularity as we are would appear blue shifted as the intervening space would be shrinking. How would you account for the cosmic background radiation that, recent studies indicate, has ?shadows? of far distant galactic clusters? If the universe were contracting, than its early density would have been very low. How would you account for the creation of matter from energy with insufficient density to provide the nuclear fireball? How did stars form?

A quick Google shows there are many who share your viewpoint. Who knows?
 
Maybe a better way to explain why we know the universe to be expanding is to simplify it a bit.
Just look at one plane in the universe, with you standing in the middle of it. Look to your left - things are moving away. Look to your right. Things are moving away. Look forward. Things are moving away. Look behind you... you guessed it... things are moving away.

Draw this on a piece of paper. Now, put your singularity on the paper that these are all heading toward, if you can.

Of course, this is ignoring other dimensions beyond the 3 dimensions we're capable of perceiving. (should more dimensions exist)

To explain that last statement, ... imagine you're on earth 5000 years ago, standing on the geographic South Pole with 4 of your closest friends, positioned around you. Suddenly each of them was attracted to the geographic North Pole, but flying in different directions at right angles to each other. If you didn't know the earth was round (hence 5000 years ago), you'd recognize that they're all moving away from the same point, but not recognize they're all moving toward the same point.

Hmmmm.... I guess that last part may actually help your argument.
 
I've thought about objects that are perpendicular to the axis of acceleration. I think they would blue shift as well. There are only two answers I can think of and neither are very satisfactory to me.

The first is that only items exactly perpendicular would blue shift. There will be some small margin close to perpendicular that would blue shift as well but it is dependent on how far away the singularity is. The further away, the smaller the margin. If the singularity were somehow an infinite distance away then there would only be an infinitely thin slice of the universe perpendicular to the motion that would blue shift. It's tough to wrap the brain around such distances but an infinitely thin slice would mean NO objects blue shift.

The second answer, and it's really not an answer, is: What direction is the singularity from here? It's the same problem that the current expanding theory has: What direction is the center of the universe? It all breaks down because we can't really comprehend infinity. If the universe extends out to infinity in every direction (talking 3 dimensional newtonian physics here) then there is no center. I usually have to fall into a mental image of two dimensional beings living on a sphere to account for it. It allows for an endless plane that is not infinite in size. It provides a little bit of perspective on additional dimensions but has limited usefullness.

The current theory is that the universe is not spherical but shaped like the Eiffel tower with a point that stretches on to infinity. It's going to take a couple years for that concept to sink in with me.

How distant this singularity is from us is the current idea I'm stewing on. I'm trying to somehow avoid infinity since it is so messy. I may not be able to.

I appreciate you guys not clowning me about my 'stupid' idea. I've spent years casually thinking about the nature of all this. It's difficult to describe since most of my thought process is visual and lacks language. I've never talked about it before.
 
Smilin

. I've spent years casually thinking about the nature of all this. It's difficult to describe since most of my thought process is visual and lacks language. I've never talked about it before.
Click to expand...

Ditto that!
 
You must log in or register to reply here.

TRENDING THREADS

Back
Top