And can you travel to that fixed point after the black hole has its way with it? And if the velocity of a black hole is so intense that it exceeds the speed of light, then would that mean we have a new speed to consider? If so can you explain what speed is that is faster than light?
21 Comments
HotsauceHurricane@lemmy.world · 23 pts · 41d
Seems like the answer to "does light have mass" is a huge resounding "maybe."
Science shenanigans
davidgro@lemmy.world · 21 pts · 41d
It's "yes, but not rest mass." - light has energy and energy is mass. (Specifically m=E/c²)
In theory a sensitive enough scale could measure the difference between a charged battery and a drained one* without the battery gaining or losing any matter. Not even electrons, since each one leaving the negative end is replaced by one going in the positive end, and vice versa when charging. This is the type of mass light has, just pure energy.
*I did the math a while back and if I remember right for a typical AA size Ni-MH battery the difference would be about the weight of a bacterium.
mkwt@lemmy.world · 3 pts · 39d
Adding on to this...
The "rest mass" is so important to physicists because it is an invariant quantity under relativistic transformations. Think about kinetic energy. Kinetic energy is a form of energy, and therefore a form of mass. But different observers at different velocities can look at the same object and come up with different kinetic energies for it. But "rest mass," the mass it would have at rest, is something everyone can agree on.
Finally, as the battery on the scale example demonstrates, photons make their own gravitational field from their energy. Since photons make gravity, they can (theoretically) make black holes. "Kugelblitz" is the name for a black hole that has been composed of only photons.
skankhunt42@lemmy.ca · 2 pts · 41d
So I'm just an idiot when I guess if a battery is good by weight vs other batteries I have. Two heavy ones must be good!
Maybe I should actually get a battery tester......
spizzat2@lemmy.zip · 3 pts · 41d
Or drop them!
TL:DW version.
davidgro@lemmy.world · 2 pts · 41d
Yeah, just get a tester. In reality the weight difference is immeasurably small (like completely swamped by dust particles)
OhmeHose@feddit.org · 1 pts · 41d
Just lick the batteries! No need for fancy tech!
hoshikarakitaridia@lemmy.world · 0 pts · 41d
So the answer is "kind of"?
heydo@lemmy.world · 10 pts · 41d
Black holes warp the fabric of space so much that not even light can escape once it passes the event horizon.
It has nothing to do with speed, it's simply that all possible paths lead into the black hole. Photons travel through the fabric of space like a car on a road. The car can't go off the road, so if the road curves, the car will have to curve with the road.
There's a lot more to it, but the most simple way to think about it is that a black hole's gravity is so strong, it warps space itself. And this warping of space basically acts like a funnel that funnels everything to the center of the black hole. Once an object or particle or whatever passes the event horizon (the point of no return) it is basically being funneled into the black hole by the fabric of space being twisted into the black hole.
Patnou@lemmy.world · 4 pts · 41d
Forgive me still have a knowledge boner...no sarcasm. But in your comparison then if a black hole is like a funnel then at the edge of it has a certain speed and speeds up when you keep going deeper? So in someway (hate to bring up fiction) Interstellar was correct or semi correct in it's portrayal of a black hole going into it? (not the timey wimey stuff). But with gravity being so strong if it warps space then that mean's just looking at one should give a viewpoint of something that is distorted to all around it? But the question I ask is the event horizon of a black hole...is that the way we can view speed through that lense, but with that said any event horizon at least should have an escape velocity like we have on earth? ......on a side not thank you for having a civilized discourse with me. It's hard to find. ...much love and if I don't reply have a great weekend.
OhmeHose@feddit.org · 3 pts · 41d
Interstellar was somewhat correct about the event horizon. In theory there also could be an escape velocity but since nothing moves faster than light nothing can escape it. Since light (speed). is the ultimate barrier for velocity.
And every mass bends the space, the small the mass the small the dent.
In science fiction and with a real theorem people "move" faster than light. But using the Alcubierre drive would require so much energy that it is (for now(?)) impossible to achieve. The drive also doesn't propel the spacecraft faster than light but bends the space around it, so technically you would more so move the space around you, instead of traveling though space.
mkwt@lemmy.world · 1 pts · 39d
It's not just excessive quantities of regular energy. These schemes all require negative mass-energy or other exotic forms of energy. We have no theory of physics that predicts the existence of these forms of energy, and we don't know how they would work.
Physicists who write papers about these things use neutral, professional language, like "exotic matter," to describe this stuff, but it's really pretty firmly in the realm of magical make believe.
heydo@lemmy.world · 1 pts · 41d
In regard to speed, the speed of light is actually the speed of causality, which is the absolute limit at which one event can influence another. It is an absolute speed limit. Light can travel at this speed limit because it is a massless particle/wave. Anything with mass would need to have infinite energy to travel at the speed of light because the faster something is traveling, the more energy it takes to accelerate it further.
Inside the event horizon, these same rules apply because it is still space and time inside the event horizon. Even light that is traveling at the speed limit cannot escape. You just can't go fast enough to escape once you are inside the event horizon, because the speed limit of the universe prevents you from going fast enough to escape. Basically you would be on your way to being spaghetti-fied as you approach the black hole, or maybe not. There is a whole lot we don't know about the inside of black holes, so who knows what could happen in there. There are theories that say that super massive black holes could have different effects on things, but I only know of them and not how to explain them.
Outside of the event horizon, you can technically escape by accelerating away. But it would require so much energy that you wouldn't want to cut it close, I would think.
Gravity does bend space and that does cause light to curve along with space. If there's enough mass, it can bend space enough to essentially make a lens that can magnify light coming from behind. A black hole can bend space so much you can see the opposite side of its accretion disk above and below the event horizon.
If you're interested, I watch a lot of Antov Petrov, Cool Worlds, Dr. Becky, and PBS Space Time on YouTube. That's where I have learned most of this stuff. PBS Space Time can be a bit hardcore sometimes, but they have tons of information.
pomegranatefern@sh.itjust.works · 5 pts · 41d
This is a long playlist but I recommend watching the videos that jump out at you: FloatHeadPhysics is really good at helping explain relativity and quantum mechanics without complicated math and building intuition. https://www.youtube.com/playlist?list=PLawLaqps30oAcpVd4r-wj8hGodzpPRYTT
Nibodhika@lemmy.world · 4 pts · 41d
No, it doesn't. Light is a wave. What is the weight of a musical note?
It doesn't, the singularity is the name by which the actual mass of the black hole is known by. In short singularity is the mass in the middle, black hole is the phenomenon caused by that mass, but they're mostly the same thing.
Sorta, think of a black hole like a drain emptying a huge pool, you can feel it sucking the water the closer you are to it. The singularity is the drain, but from the outside you can feel the water being pulled from much farther away, and that's the black hole.
What point? The singularity? No. That is the black hole, it's like asking whether you can travel to the sun after the star had its way with it, you're using two words that mean the same as if they were different things.
Black holes don't have any velocity, they just are. Think on the drain example I gave, the drain is not moving, but the water around it is.
No speed is faster than light. Again, light is a wave, not a physical object, imagine the drain again, you're making ripples in the water, and you see that those ripples get near the drain and are "pulled down", you might conclude that the ripples are attracted to the hole, but in reality it's just that the medium they're moving on (water) is being pulled into it and so ripples on that medium get dragged along.
southsamurai@sh.itjust.works · 1 pts · 41d
That is an excellent breakdown!
BreadOven@lemmy.world · 1 pts · 41d
Light is a wave until it starts acting as a particle.....
lung@lemmy.world · 3 pts · 41d
Look man Ive spent many years tryna understand this shit and in fact nobody does. Event horizons aren't really even a fixed place, and you could pass one without realizing if the BH is big enough. Then there's time dialation. Speed of light is relative to the observer
My rec is to expect no answers but if you find it fascinating, then spend the next year watching PBS Spacetime on Youtube and stay rock hard, nerd metaphorically speaking
Zwuzelmaus@feddit.org · 1 pts · 41d
Of course you need to read Einstein first. It all starts there.
For example one of his first articles https://dn760106.eu.archive.org/0/items/EinsteinsOriginaltextZurRelativittstheorie/Physik_Einstein_text.pdf
leraje@piefed.blahaj.zone · 1 pts · 41d
I think photon's don't have mass but they do have energy and that can mean they act in the same way? In that they are subject to gravity. That could be very wrong though, I'm going off my own non-scientist memory of a popular science book.
GoofSchmoofer@lemmy.world · 1 pts · 41d
Kolanaki@pawb.social · 0 pts · 41d
Light does have mass, it is just immeasurably small. That's how a solar sail would work: the light would be physically pushing the sail. It's not a lot, individually, but there's a lot of light hitting it, so it pushes it forward.
Diddlydee@feddit.uk · -1 pts · 41d