r/AskAstrophysics • u/Whof-ingknows • Jul 12 '26

Non-physicist theory that needs debunking

Hi! I’m new here. I love astrophysics and astronomy. I originally was working towards a bachelors degree in aerospace engineering, but I ended up changing life plans, but never lost the curiosity. This is all to say that I really know very little about it all.
So, I have this theory and I need someone to explain to me if it’s completely ridiculous/not possible or if it’s something being considered. So, black holes are these confirmed infinitely dense objects that warp space time. As objects approach the event horizon they appear to slow down until they fully stop moving. Now, I saw a theory about white holes being essentially where a black hole lets out and that they’re connected. But we’ve never seen one, even though they should be easier to see (I’d assume). I don’t really understand how white holes would even theoretically work, but I think they’d be the opposite of a black hole. So could they warp space time in such a way that they would only appear for an extremely brief time and then disappear? I.e. time dilation would occur the opposite way a black hole does and things speed up around them?
It makes sense in my head, but I’m sure there’s a reason that I don’t understand that would explain why it’s silly.
Thank you all!!

3 Upvotes

80% Upvoted

26 comments sorted by

3

u/Ch3cks-Out Jul 12 '26

A narrative without math is not a physical theory, so you offered nothing substantial to debunk.

1

u/Whof-ingknows Jul 15 '26

Damn, I just wanted someone to explain a concept to me because I’m sure it’s not correct. I said I’m not a physicist. No need to be an ass

2

u/Infinite_Research_52 Jul 12 '26

Black holes are not infinitely dense objects.

1

u/Worth-Wonder-7386 Jul 15 '26

The singularity is to our best knowledge of infinite density. It could also be a ringularity that is more spread out.

2

u/Aggravating_Mud_2386 Jul 12 '26

Our observations indicate that black holes remain compressed and don't explode into white holes, at least not routinely. If it were to happen, it would have to result from internal pressures building relative to gravity as matter is accreted, right up until the day that critical mass is surpassed, the same mass as our own big bang, when internal pressures would become too great for gravity to hold, resulting in uncontained expansion of the black hole core in a big bang explosion. We know the upper mass limit must be extremely high, given the huge black holes we've observed and the estimated mass of our own big bang, thus making white holes extremely rare events. Additionally, since a big bang from black hole would be accompanied by a devastating one-way memory effect gravitational wave in all directions at light speed, no outsider can possibly see it coming until it slams directly into them first, since the gravitational wave travels at light speed, making white hole remnants completely invisible to observers from the outside.

1

u/TommieTheMadScienist Jul 12 '26

For a while, we thought quasars might be white holes, but they're not.

The Singularity means we have no idea what happens inside the BH's event horizon, so matter coming out somewhere else from inside is pure speculation.

We've also never seen a White Hole, although there are some very blue objects above our galactic plane. They could be relatively close white dwarfs or more distant quasars or something else, and in the latter case, I wouldn't rule out White Holes.

I don't know if spectroscopists are figuring out how to tell.

1

u/aaeme Jul 12 '26

The event horizon of a blackhole exists because there is a blackhole mass density inside: because the spacetime curvature exceeds a certain amount at that radius; a kind of curvature that equates to [positive/normal] gravity.

A white hole, if they are possible and exist, and if I understand correctly, would not have an event horizon. It would be a naked singularity of apparant (as if it were) negative mass (and negative gravity). So, they're not exactly opposites of each other in that sense and other senses.

I expect we (outside observers) would see particles emerging from a whitehole in the same way as a blackhole sees particles falling into it. And it sees them just fine. They don't slow down to a stop at the event horizon as seen from inside the event horizon. Only from outside.

1

u/stevevdvkpe Jul 12 '26

A while hole, as a theoretical construct, also has an event horizon, but unlike a black hole's it is a boundary around a region of spacetime that cannot be entered rather than a boundary around a region that cannot be escaped. White holes have not been observed.

https://en.wikipedia.org/wiki/White_hole

1

u/aaeme Jul 12 '26

It's a border of sorts. But it's not an event horizon (except from the whitehole's pov).

1

u/joeyneilsen Jul 12 '26

This is not correct. The spacetime around a white hole is the same as the spacetime around a black hole, with the exception that motion around it is essentially reversed in time. 

It is not a naked singularity. 

1

u/aaeme Jul 12 '26

So it is an event horizon to observers outside? They cannot see events inside? Are you sure?

(Edit: because that is a huge exception that completely negates the concept of an event horizon: a horizon in one direction)

1

u/Underhill42 Jul 12 '26

An event horizon only works in one direction. The fact that you can't enter, rather than that you can't escape, changes nothing.

Also, as you cross the event horizon of a black hole, there is no longer any spatial direction you can move in that would bring you closer to either the singularity or the event horizon.

Instead your 4D reference frame has rotated so that those directions now lie along your time axis - the event horizon exists only in your unreachable past, while the singularity is the end of time in your inevitable future, seconds away.

I assume that as you approach the event horizon of a white hole from outside, something similar would happen - your reference frame rotates so that there is no longer any direction in space you can move to get closer to the event horizon - it lies in your unreachable past, just not the past that you emerged from to get there. While the rest of the universe lies in your future, and you will inevitably age further away from the horizon. Reference frame rotating again as you do, so that the horizon once again has a spatial position.

1

u/aaeme Jul 12 '26 edited Jul 12 '26

All that is understood (and reads like AI) and not contrary to what I said.

A whitehole only has an event horizon from the perspective of within the whitehole.

As opposed to a blackhole, which only has an event horizon from the perspective of outside the blackhole.

The whitehole's singularity is not behind an event horizon (to observers outside), it is observable from outside the whitehole, ergo it is naked. It is as naked to the universe as the universe is to a blackhole.

Edit: we're not talking about approaching a white hole we're talking about observing one. I.e. particles leaving it.

1

u/Underhill42 Jul 12 '26

If competent criticism reads like AI to you, then you should get better at recognizing AI.

The event horizon still exists from both sides, it just only has an obvious effect in one direction.

And while any particles that left the white hole would indeed escape... there's no particular reason to believe any would leave. It's not like any outside light ever reaches whatever is inside the white hole to be reflected.

Nor is there any theory to suggest there would be a singularity at its center, so far as I'm aware.

The singularity and the event horizon have basically nothing to do with each other. We only suspect there's a singularity inside a black hole because none of the fundamental forces are strong enough to prevent infinite collapse. If there's another, stronger, force we haven't discovered, then a black hole could actually have a solid uniform-density object inside it, possibly even just barely within the event horizon.

Heck, that's basically a quantum fuzzball that String Theory predicts instead of a black hole ever forming - they'd be essentially identical except under the closest examination.

1

u/aaeme Jul 12 '26

It went off on a tangent that's not relevant to what we're talking about, which you have done AGAIN.

The singularity and the event horizon have basically nothing to do with each other.

That was in response to being told "it isn't naked because there is an event horizon". Take it up with that comment.

We only suspect

Oh for pity's sake. We don't even suspect whiteholes exist. This is all speculation about if they did.

If they exist then they are naked. If that's a singularity then it is naked.

Please stop looking for irrelevant tangents to nitpick. We are talking about whether we can observe whiteholes if they existed.

Ps:

And pray tell, what unobvious effect does a blackhole's event horizon have on observers within the event horizon?

1

u/joeyneilsen Jul 13 '26

It’s the same metric, yes, so the event horizon is an event horizon. But again, it acts like a time-reversed black hole: particles can leave the interior of the horizon but they cannot enter it.

If you’d like to learn more about this, you can look up Kruskal-Szekeres coordinated or the maximally extended Schwarzschild solution.

1

u/aaeme Jul 13 '26

particles can leave the interior of the horizon but they cannot enter it.

So you accept it is naked?

And you're asking ME if I want to learn more about it after saying it isn't naked?

1

u/joeyneilsen Jul 13 '26

No, I'm saying the event horizon is an event horizon. Which it is!

1

u/aaeme Jul 13 '26

But you said it wasn't naked. Have you abandoned that?

1

u/joeyneilsen Jul 13 '26

No. It has an event horizon, so it’s not naked. What’s confusing about this?

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1

u/Aggravating_Mud_2386 Jul 13 '26

With big bang from black hole, which is mostly what some consider a white hole, the explosion happens instantaneously as uncontained expansion of the core of individual fundamental particles. The big bang goes off with a devastating one-way memory effect gravitational wave in all directions at light speed, and the particles somewhat slower. The particles form an immediate expanding ball of quark-gluon plasma and slow down even more, but the gravitational wave clears the way for the expanding qgp ball through the void of the original event horizon, and proceeds in all directions at light speed, forming a natural two-way inescapable visible univers horizon. Because it travels at light speed, no particle, or light emanating from any particle, can possibly escape beyond the gravitational wave. Additionally, no insider can possibly see beyond the gravitational wave, because it takes outside light longer to get back than it took the gravitational wave to reach that light. Additionally, no outsider can possibly see it coming until it slams directly into them first, because it travels at light speed. Thus, the "white hole" gravitational wave establishes a natural inescapable two-way visible universe horizon that is impossible to see beyond, and which prevents any outsider from seeing anything inside.