time reversibility is something we "don't know" in a purely academic sense where, sure, it underpins our entire understanding of everything, and is related to countless observations we've made over more than a century, but yes, we can't empirically state it is true
a kugelblitz is an absurdity that is fully possible according to the math, and we have absolutely no chance of discovering whether or not it actually is possible any time conceivably soon, but it's a fun and interesting thing to think about
I would think that time reversability is required for cause and effect to be true though? It's an axiom, without which I can't see how we can meaningfully talk about pretty much any scientific concept. It's essentially saying this: If I do a, that causes b, but then reverse the process (which in this case involves reversing time) and b does not transform back into a having happened. Doesn't that mean an effect can be decoupled from a cause? If you throw away time reversability as an axiom, and don't just assume it, how can you talk about anything?
(PSN: Morninglord) (Steam: Morninglord) (WiiU: Morninglord22) I like to record and toss up a lot of random gaming videos here.
time reversibility is something we "don't know" in a purely academic sense where, sure, it underpins our entire understanding of everything, and is related to countless observations we've made over more than a century, but yes, we can't empirically state it is true
a kugelblitz is an absurdity that is fully possible according to the math, and we have absolutely no chance of discovering whether or not it actually is possible any time conceivably soon, but it's a fun and interesting thing to think about
I would think that time reversability is required for cause and effect to be true though? It's an axiom, without which I can't see how we can meaningfully talk about pretty much any scientific concept. It's essentially saying this: If I do a, that causes b, but then reverse the process (which in this case involves reversing time) and b does not transform back into a having happened. Doesn't that mean an effect can be decoupled from a cause? If you throw away time reversability as an axiom, and don't just assume it, how can you talk about anything?
You tack Charge and Parity symmetry onto it, and hope no one finds a natural phenomena that violates all three at once, instead of just time symmetry alone?
This seems like an inappropriate mathematization of a concept if they have no basis for it following the basic rules of mathematics.
Also, the equation in this case that we are talking about is E=mc^2 and correct me if I am wrong but time is not a part of that, right? So that doesn't really matter here?
The thought experiment involved here does not rely on reversing time in order to create the black hole out of light. It's super simple: add lots of energy to a small space. That is technically but perhaps not practically possible, without asking for time to change in anyway, other than to continue on working like it always has.
Do you have a better mathematical construction to describe it? An equation is just relationship. That is all it is.
An example. Delta sunlight on the earth corresponds directly to the sun rising. It’s an equation. But this does not mean that I can cause the sun to rise by increasing radiation onto the earth. I will have broken the equation if I try.
I will still write that as an equality when describing the rule though. We still write probability distributions as equalities.
My point was that you should not necessarily think physics are possible because the current math says they are. The current math is not reality. It is a model we use to predict it that is working pretty well and we update when we find it no longer holds.
Until someone actually collides some light and produces mass we won’t know if it works or if we are trying to turn on a light bulb in order to make the sun rise.
I would think that time reversability is required for cause and effect to be true though?
It time is reversible then there is no such thing as cause and effect. They are one and the same is it not? A causes b as much as b causes a.
You are confusing a function of the math (I can run time backwards and forwards in order to determine what happens or has happened in a system) to determine an actual aspect of the universe (time can flow in reverse)
Edit: and if you won’t take my word for it take Einstein’s. Who did not think that black holes were real. He just thought it was a problem with the math. Edit2: obviously this does not mean that we cannot turn energy into mass(Einstein was wrong here, after all) it just means we don’t actually know.
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BrodyThe WatchThe First ShoreRegistered Userregular
Does the deformation of space inside a black hole every actually end, or is there a "halfway to the goal" paradox? Or does it punch through the fabric of spacetime? Also, how big would the "cylinder/cone" created by this deformation be?
I realize the 2d representation is flawed, but I saw a video the other night that explained time dilation via gravity as light having to travel farther, but part of it's motion is now perpendicular to our view, and so it looks like it's slowed down because we can't actually see the full distance travelled.
Which reminded me of the "are we in a black whole" conversation, but we are fairly certain we aren't in a cylinderical space, so either the circumference of the black hole is unbelievably massive, the stretching/rotating of space makes things weird, or like, or the theory fails.
Although it's not actually a 2d space, so there isn't an empty hole in the fabric of space. Unless its like the dark cone of the universe?
"I will write your name in the ruin of them. I will paint you across history in the color of their blood."
This seems like an inappropriate mathematization of a concept if they have no basis for it following the basic rules of mathematics.
Also, the equation in this case that we are talking about is E=mc^2 and correct me if I am wrong but time is not a part of that, right? So that doesn't really matter here?
The thought experiment involved here does not rely on reversing time in order to create the black hole out of light. It's super simple: add lots of energy to a small space. That is technically but perhaps not practically possible, without asking for time to change in anyway, other than to continue on working like it always has.
Do you have a better mathematical construction to describe it? An equation is just relationship. That is all it is.
I would suggest they not use the regular equals sign for things they cannot be sure equate both ways, but instead create a one way equals sign, and use that. It's physics, not math. It doesn't have to use regular math. They can invent their own. They can switch to using the traditional = formulation for statements when they have tested that it is in fact reversible. This is because the = sign implies you CAN equalise by swapping things around to either side of the equation, such as by saying m=e/c^2, and that this makes sense and you can get it to happen. And if they do not know that is true, they should not use it. Remember that math is just formalised logic. They can, have in the past, and will in the future, invented new symbols to solve problems such as this.
This is actually a very common problem in science, the misappropriation of mathematical concepts, and leads to issues in conceptions about reality such as you think I'm making (although I'm not, as I'll explain in a bit).
An example. Delta sunlight on the earth corresponds directly to the sun rising. It’s an equation. But this does not mean that I can cause the sun to rise by increasing radiation onto the earth. I will have broken the equation if I try.
I will still write that as an equality when describing the rule though. We still write probability distributions as equalities.
My point was that you should not necessarily think physics are possible because the current math says they are. The current math is not reality. It is a model we use to predict it that is working pretty well and we update when we find it no longer holds.
Until someone actually collides some light and produces mass we won’t know if it works or if we are trying to turn on a light bulb in order to make the sun rise.
This is a good point I completely agree with but I thougt the fact that m=e/c^2 actually did have some experimental evidence behind it? I thought the mass energy equivalence was not theoretical but actually an observed effect? The only question in this case of a kugelblitz is that the amount of energy required to make a black hole of that specific size is ridiculously high and leads to other problems. ie what I understand is that it is not that energy cannot result in mass, but that we dont know what would happen if we tried to create enough mass out of energy to make a black hole. That's a different issue.
If I am wrong then the discussion on this topic of e=mc^2 is over, since the only reason I even said its reversible is because I thought that was already known.
I would think that time reversability is required for cause and effect to be true though?
It time is reversible then there is no such thing as cause and effect. They are one and the same is it not? A causes b as much as b causes a.
I wouldn't say that. It just means we have to indicate which direction time is flowing to determine which is the cause and which is the effect. I can rewind a movie, does this mean the things I saw happen at the start of the movie didn't really cause what happens later when I play it back normally? It gets more complicated to talk about it, but it doesn't stop existing.
Whereas if you rewind the movie and the start then changes into a different movie you've got a bit of an issue. Especially because now what happens when you press play?
You are confusing a function of the math (I can run time backwards and forwards in order to determine what happens or has happened in a system) to determine an actual aspect of the universe (time can flow in reverse)
I'm not actually, since I'm not at all assuming time can flow backwards.
An axiom is a thing you have to assume is true in order to move forward. It's a point about logic, not about my understanding of how theoretical concepts relate to reality, or my beliefs about whether something is true in reality. I'm not saying its TRUE that if time goes backwards things are reversed. Nor have I ever said it is POSSIBLE for time to reverse, in reality.
I'm say we must ASSUME its true that if it DOES reverse, the start of the movie will be the same movie we had originally. This is a completely different point (its a different point entirely even to the one about reversing equations, since now we are discussing a tangent topic that sprang out of that), and its a point about philosophy of science, not reality.
It's entirely possible its not true because the universe doesn't have to be sensible, but if it ISNT true, I would suggest the next step isn't a physics experiment but picking up a bible and praying to god. Cos now shits gone nuts.
I have not yet acknowledged this because I've been sidetracked with other things, so I'm making it very clear to you that this point of yours about models not needing to match reality is true, I agree, and we are all good on that. I regularly argue that in similar topics and I learnt this in my science degree, which I take very seriously. I actually just thought energy mass equivalence had been shown before. If this isn't true, then that's the mistake I'm making here: my knowledge is wrong.
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While there were multiple experiments with evidence of mass-energy equivalence even prior to Einstein, the first pure example of conversion of energy to mass and mass to energy was experimentally demonstrated in 1933 by Irène and Frédéric Joliot-Curi with electron-positron pair creation and annihilation. https://encyclopedia2.thefreedictionary.com/Annihilation+and+Creation+of+Particle-Antiparticle+Pairs
Just remember that half the people you meet are below average intelligence.
Different bit of astrophysics maybe- does anyone know what's being modeled in the simulation behind Scott Manley starting at the linked point (4:03) in this video? He's talking about a supernova, but this is a blast that starts at the center of a sphere and jets outwards, which is not how I expected that would go!
While there were multiple experiments with evidence of mass-energy equivalence even prior to Einstein, the first pure example of conversion of energy to mass and mass to energy was experimentally demonstrated in 1933 by Irène and Frédéric Joliot-Curi with electron-positron pair creation and annihilation. https://encyclopedia2.thefreedictionary.com/Annihilation+and+Creation+of+Particle-Antiparticle+Pairs
Thus the question is not about the destruction or spontaneous evolution of matter but about the interconversion of particles.
Mass creation from energy has not been observed (yet)…
Different bit of astrophysics maybe- does anyone know what's being modeled in the simulation behind Scott Manley starting at the linked point (4:03) in this video? He's talking about a supernova, but this is a blast that starts at the center of a sphere and jets outwards, which is not how I expected that would go!
While there were multiple experiments with evidence of mass-energy equivalence even prior to Einstein, the first pure example of conversion of energy to mass and mass to energy was experimentally demonstrated in 1933 by Irène and Frédéric Joliot-Curi with electron-positron pair creation and annihilation. https://encyclopedia2.thefreedictionary.com/Annihilation+and+Creation+of+Particle-Antiparticle+Pairs
Thus the question is not about the destruction or spontaneous evolution of matter but about the interconversion of particles.
Mass creation from energy has not been observed (yet)…
Baryons are still believed to be conserved as far as I know though
The 1933 experiment of gamma rays entering a cloud chamber, interacting, and producing electron-positron pairs is energy to mass conversion. A massless bit of energy went in and two particles with mass were produced.
The experiment you linked is about the Breit–Wheeler process where two photons collide to produce an electron-positron pair. It's a more direct mechanism for energy to mass conversion than the cloud chamber experiment (and others), but far more difficult to achieve as photons normally do not interact.
Two different mechanisms. Both demonstrate energy to mass conversion.
Just remember that half the people you meet are below average intelligence.
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MorninglordI'm tired of being Batman,so today I'll be Owl.Registered Userregular
edited May 2022
I'm sidetracked again.
A thing I noticed in that invariant mass link is that two photons not travelling in parallel can have invariant mass.
Is this the same process? Do they have to be close? Do they have to collide? Trying to wrap my head around it.
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Different bit of astrophysics maybe- does anyone know what's being modeled in the simulation behind Scott Manley starting at the linked point (4:03) in this video? He's talking about a supernova, but this is a blast that starts at the center of a sphere and jets outwards, which is not how I expected that would go!
It's a simulation of a type 1a supernova. It's not a core-collapse Type II supernova which is what you're probably thinking of.
The distinction is that a 1a occurs when a white dwarf siphons mass from the envelope of a larger star, and gains sufficient mass to restart fusion and explodes. They're the least energetic type of supernova, but also the most common. Also, because they always happen at a very specific mass limit and thus have a very narrow range of brightness and energy, they're extremely useful for determining intergalactic distances.
A thing I noticed in that invariant mass link is that two photons not travelling in parallel can have invariant mass.
Is this the same process? Do they have to be close? Do they have to collide? Trying to wrap my head around it.
The invariant mass (rest mass) of a system of non-parallel photons exists regardless of whether they interact or not. It's a consequence of photons having momentum and a system of multiple non-parallel photons not having a rest frame where all photons are non-moving.
One thing I forgot to mention in my previous reply as it relates to what kicked off this discussion is that while you would likely have pair creation energy to mass conversion occur when trying to create a Kugelblitz from all the photons flying around, that is just a side effect. A Kugelblitz is not formed because you are creating particles with mass from massless photons. It is formed because the concentration of energy in a limited area as described by the stress-energy tensor of general relativity causes enough spacetime curvature to form an event horizon. GR doesn't need "real" mass to produce that curvature.
Just remember that half the people you meet are below average intelligence.
A thing I noticed in that invariant mass link is that two photons not travelling in parallel can have invariant mass.
Is this the same process? Do they have to be close? Do they have to collide? Trying to wrap my head around it.
The invariant mass (rest mass) of a system of non-parallel photons exists regardless of whether they interact or not. It's a consequence of photons having momentum and a system of multiple non-parallel photons not having a rest frame where all photons are non-moving.
One thing I forgot to mention in my previous reply as it relates to what kicked off this discussion is that while you would likely have pair creation energy to mass conversion occur when trying to create a Kugelblitz from all the photons flying around, that is just a side effect. A Kugelblitz is not formed because you are creating particles with mass from massless photons. It is formed because the concentration of energy in a limited area as described by the stress-energy tensor of general relativity causes enough spacetime curvature to form an event horizon. GR doesn't need "real" mass to produce that curvature.
Still absolutely terrifying to me! Like I know it's not really different from what we consider a normal black hole, but somehow the concept of creating a black hole without feeding it ridiculous amounts of mass is terrifying.
While there were multiple experiments with evidence of mass-energy equivalence even prior to Einstein, the first pure example of conversion of energy to mass and mass to energy was experimentally demonstrated in 1933 by Irène and Frédéric Joliot-Curi with electron-positron pair creation and annihilation. https://encyclopedia2.thefreedictionary.com/Annihilation+and+Creation+of+Particle-Antiparticle+Pairs
Thus the question is not about the destruction or spontaneous evolution of matter but about the interconversion of particles.
Mass creation from energy has not been observed (yet)…
Baryons are still believed to be conserved as far as I know though
Doesn’t observing a black hole imply creation of mass from energy? If light can be captured by a black hole event horizon (which presumably it can) then energy is being converted to mass.
Edit: also some nuclear reactions such as neutron capture in elements heavier than iron should include conversion of energy into small amounts of mass.
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MorninglordI'm tired of being Batman,so today I'll be Owl.Registered Userregular
While there were multiple experiments with evidence of mass-energy equivalence even prior to Einstein, the first pure example of conversion of energy to mass and mass to energy was experimentally demonstrated in 1933 by Irène and Frédéric Joliot-Curi with electron-positron pair creation and annihilation. https://encyclopedia2.thefreedictionary.com/Annihilation+and+Creation+of+Particle-Antiparticle+Pairs
Thus the question is not about the destruction or spontaneous evolution of matter but about the interconversion of particles.
Mass creation from energy has not been observed (yet)…
Baryons are still believed to be conserved as far as I know though
Doesn’t observing a black hole imply creation of mass from energy? If light can be captured by a black hole event horizon (which presumably it can) then energy is being converted to mass.
We don't know what happens to the light inside an event horizon (we don't know what happens to anything inside a black hole for real, its all just educated guesstimates and desperate attempts to create a solution that doesn't break the universe) and the hole you see in pictures of black holes is significantly larger than the actual event horizon, because light is bent around and captured by the black hole far outside of the event horizon.
So we only ever see light that hasn't been caught.
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BrodyThe WatchThe First ShoreRegistered Userregular
I realize that this is basically just "modified gravity", but what if "dark matter" is just a reinforcing wave between particles. If it were wavelike, shouldn't it resonate at certain frequencies? And then also, if the frequencies are far apart in amplitude, the smaller one kind of gets eaten, but as they near being the same, wouldn't they harmonize, spiking the gravity, and then forcing them to stay at that harmony until they bleed all of the energy out of the system as a standing wave? Or am I really bad at understanding frequency?
"I will write your name in the ruin of them. I will paint you across history in the color of their blood."
MorninglordI'm tired of being Batman,so today I'll be Owl.Registered Userregular
I honestly didn't really understand what you said, but afaik something like 95% of the mass is unaccounted for so that's a pretty hefty harmonizing wave.
(PSN: Morninglord) (Steam: Morninglord) (WiiU: Morninglord22) I like to record and toss up a lot of random gaming videos here.
I realize that this is basically just "modified gravity", but what if "dark matter" is just a reinforcing wave between particles. If it were wavelike, shouldn't it resonate at certain frequencies? And then also, if the frequencies are far apart in amplitude, the smaller one kind of gets eaten, but as they near being the same, wouldn't they harmonize, spiking the gravity, and then forcing them to stay at that harmony until they bleed all of the energy out of the system as a standing wave? Or am I really bad at understanding frequency?
I think you need to explain for precepts here: what is the reinforcing wave meant to be?
The wavefunction of solid matter is generally tiny - this is why electron microscopes are a thing, because an accelerated electron has a much shorter wavelength (and much better diffraction limit) then electromagnetic radiation.
So there are no cosmic scale matter-wavefunctions hanging about.
There's also other problems with the idea: if matter were periodically gaining a lot more gravitational mass, then we'd see the effects quite clearly because that would make a big change in behavior, and regular matter we are very good at seeing.
A thing I noticed in that invariant mass link is that two photons not travelling in parallel can have invariant mass.
Is this the same process? Do they have to be close? Do they have to collide? Trying to wrap my head around it.
The invariant mass (rest mass) of a system of non-parallel photons exists regardless of whether they interact or not. It's a consequence of photons having momentum and a system of multiple non-parallel photons not having a rest frame where all photons are non-moving.
One thing I forgot to mention in my previous reply as it relates to what kicked off this discussion is that while you would likely have pair creation energy to mass conversion occur when trying to create a Kugelblitz from all the photons flying around, that is just a side effect. A Kugelblitz is not formed because you are creating particles with mass from massless photons. It is formed because the concentration of energy in a limited area as described by the stress-energy tensor of general relativity causes enough spacetime curvature to form an event horizon. GR doesn't need "real" mass to produce that curvature.
Still absolutely terrifying to me! Like I know it's not really different from what we consider a normal black hole, but somehow the concept of creating a black hole without feeding it ridiculous amounts of mass is terrifying.
If it helps the amount of energy is so gigantic and concentrated that we don't really know of any conditions in our universe that would result in one
A thing I noticed in that invariant mass link is that two photons not travelling in parallel can have invariant mass.
Is this the same process? Do they have to be close? Do they have to collide? Trying to wrap my head around it.
The invariant mass (rest mass) of a system of non-parallel photons exists regardless of whether they interact or not. It's a consequence of photons having momentum and a system of multiple non-parallel photons not having a rest frame where all photons are non-moving.
One thing I forgot to mention in my previous reply as it relates to what kicked off this discussion is that while you would likely have pair creation energy to mass conversion occur when trying to create a Kugelblitz from all the photons flying around, that is just a side effect. A Kugelblitz is not formed because you are creating particles with mass from massless photons. It is formed because the concentration of energy in a limited area as described by the stress-energy tensor of general relativity causes enough spacetime curvature to form an event horizon. GR doesn't need "real" mass to produce that curvature.
Still absolutely terrifying to me! Like I know it's not really different from what we consider a normal black hole, but somehow the concept of creating a black hole without feeding it ridiculous amounts of mass is terrifying.
If it helps the amount of energy is so gigantic and concentrated that we don't really know of any conditions in our universe that would result in one
Eh... it's density, right?
Maybe, if you get it to converge into a wave length of the light, you only need enough energy to produce a back hole nanometers in circumference.
It would evaporate very quickly, and well... that kinda goes out the window because we don't really have a theory of gravity for stuff on that scale.
Otherwise you're atuck trying to figure out if a gama ray burst can get gravitationally lensed, by a black hole, with no accreditation disk, can focus the energy tight enough. But.... maybe there are numbers you can plug into that were it works?
Believe it or not, none of those things are enough.
Gravitational lensing has a similar limit to a glass lens. What's the hottest temperature you can make with a lens in sunlight? If you're in a vacuum, about the same temperature as the surface of the sun, because that image you're making of the sun is composed of the light from the radial diameter of the magnifying lens, and the "point" you focus on is actually the size as the same radial diameter section of the surface of the sun, not a true point.
With a perfect gravitational lens, you can focus some of the energy of an event, but the focal point peaks at about the same energy density as the event itself.
Reading over it a bit it seems there’s also some thought that the collision of high energy photons might spontaneously produce matter/antimatter pairs, which due to the high energy of the system would tend to be ejected in some cases instead of immediately annihilating. If this occurs enough to be significant it would make it a lot more impractical to concentrate the necessary amount of energy. You may reach an equilibrium point where the energy leaving the system by radiating particles is for any realistic amount of input energy large enough to prevent the density from reaching dense enough levels to form a black hole.
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ChanusHarbinger of the Spicy Rooster ApocalypseThe Flames of a Thousand Collapsed StarsRegistered Userregular
Earth's mass is somewhere around 6 x 10²⁴ kg, which would create a black hole with an event horizon of about 16mm if i remember all that correctly
to do that with light is E = 6x10²⁴kg x c² in photons concentrated into a small enough point to collapse in on itself
and we'd not have any chance of noticing the result unless it were extremely close to us
how that would possibly be able to happen in nature seems to stretch beyond belief but it is an interesting thing the math says is possible
Earth's mass is somewhere around 6 x 10²⁴ kg, which would create a black hole with an event horizon of about 16mm if i remember all that correctly
to do that with light is E = 6x10²⁴kg x c² in photons concentrated into a small enough point to collapse in on itself
and we'd not have any chance of noticing the result unless it were extremely close to us
how that would possibly be able to happen in nature seems to stretch beyond belief but it is an interesting thing the math says is possible
possible doesn't mean it exists
The problem is also that quantum gravity almost certainly gets involved in this sort of thing, and we have no theory of it.
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MorninglordI'm tired of being Batman,so today I'll be Owl.Registered Userregular
edited May 2022
I walked through a museum about SCIENCE! near me a few years back which is where I learnt there's some theories that some of gravity may be caught up in other dimensions and that's why its weaker than expected.
At the time I thought "that's cool" but didn't really understand what they meant by dimensions. Which dimensions?
I just got reminded of it, so uh, anyone here know?
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I walked through a museum about SCIENCE! near me a few years back which is where I learnt there's some theories that some of gravity may be caught up in other dimensions and that's why its weaker than expected.
At the time I thought "that's cool" but didn't really understand what they meant by dimensions. Which dimensions?
I just got reminded of it, so uh, anyone here know?
I walked through a museum about SCIENCE! near me a few years back which is where I learnt there's some theories that some of gravity may be caught up in other dimensions and that's why its weaker than expected.
At the time I thought "that's cool" but didn't really understand what they meant by dimensions. Which dimensions?
I just got reminded of it, so uh, anyone here know?
It's the dimension without shrimp.
A dimension without lemons.
Anyway: that was probably string theory? Iirc that one involves there being multiple additional dimensions on top of time xyz but they're set up in such a way we never see them.
Because the string math requires they exist or it doesn't work out right. To date as far as I know no one has figured out how to test this.
That isn't string theory. String theory dimensions are too small to contain gravity. The extra gravity dimension turns up in "brane" theories which propose an extra, large spatial dimension which gravity expands into, in which spacetime is embedded (along side other branes).
In that version, the big bang was two branes colliding, and possibly the one our universe hit is a couple millimetres away from us on that extra axis.
However, tests of brane theory predictions have put some pretty hard constraints on their viability.
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I would think that time reversability is required for cause and effect to be true though? It's an axiom, without which I can't see how we can meaningfully talk about pretty much any scientific concept. It's essentially saying this: If I do a, that causes b, but then reverse the process (which in this case involves reversing time) and b does not transform back into a having happened. Doesn't that mean an effect can be decoupled from a cause? If you throw away time reversability as an axiom, and don't just assume it, how can you talk about anything?
You tack Charge and Parity symmetry onto it, and hope no one finds a natural phenomena that violates all three at once, instead of just time symmetry alone?
Do you have a better mathematical construction to describe it? An equation is just relationship. That is all it is.
An example. Delta sunlight on the earth corresponds directly to the sun rising. It’s an equation. But this does not mean that I can cause the sun to rise by increasing radiation onto the earth. I will have broken the equation if I try.
I will still write that as an equality when describing the rule though. We still write probability distributions as equalities.
My point was that you should not necessarily think physics are possible because the current math says they are. The current math is not reality. It is a model we use to predict it that is working pretty well and we update when we find it no longer holds.
Until someone actually collides some light and produces mass we won’t know if it works or if we are trying to turn on a light bulb in order to make the sun rise.
It time is reversible then there is no such thing as cause and effect. They are one and the same is it not? A causes b as much as b causes a.
You are confusing a function of the math (I can run time backwards and forwards in order to determine what happens or has happened in a system) to determine an actual aspect of the universe (time can flow in reverse)
Edit: and if you won’t take my word for it take Einstein’s. Who did not think that black holes were real. He just thought it was a problem with the math. Edit2: obviously this does not mean that we cannot turn energy into mass(Einstein was wrong here, after all) it just means we don’t actually know.
I realize the 2d representation is flawed, but I saw a video the other night that explained time dilation via gravity as light having to travel farther, but part of it's motion is now perpendicular to our view, and so it looks like it's slowed down because we can't actually see the full distance travelled.
Which reminded me of the "are we in a black whole" conversation, but we are fairly certain we aren't in a cylinderical space, so either the circumference of the black hole is unbelievably massive, the stretching/rotating of space makes things weird, or like, or the theory fails.
Although it's not actually a 2d space, so there isn't an empty hole in the fabric of space. Unless its like the dark cone of the universe?
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This is actually a very common problem in science, the misappropriation of mathematical concepts, and leads to issues in conceptions about reality such as you think I'm making (although I'm not, as I'll explain in a bit).
This is a good point I completely agree with but I thougt the fact that m=e/c^2 actually did have some experimental evidence behind it? I thought the mass energy equivalence was not theoretical but actually an observed effect? The only question in this case of a kugelblitz is that the amount of energy required to make a black hole of that specific size is ridiculously high and leads to other problems. ie what I understand is that it is not that energy cannot result in mass, but that we dont know what would happen if we tried to create enough mass out of energy to make a black hole. That's a different issue.
If I am wrong then the discussion on this topic of e=mc^2 is over, since the only reason I even said its reversible is because I thought that was already known.
I wouldn't say that. It just means we have to indicate which direction time is flowing to determine which is the cause and which is the effect. I can rewind a movie, does this mean the things I saw happen at the start of the movie didn't really cause what happens later when I play it back normally? It gets more complicated to talk about it, but it doesn't stop existing.
Whereas if you rewind the movie and the start then changes into a different movie you've got a bit of an issue. Especially because now what happens when you press play?
I'm not actually, since I'm not at all assuming time can flow backwards.
An axiom is a thing you have to assume is true in order to move forward. It's a point about logic, not about my understanding of how theoretical concepts relate to reality, or my beliefs about whether something is true in reality. I'm not saying its TRUE that if time goes backwards things are reversed. Nor have I ever said it is POSSIBLE for time to reverse, in reality.
I'm say we must ASSUME its true that if it DOES reverse, the start of the movie will be the same movie we had originally. This is a completely different point (its a different point entirely even to the one about reversing equations, since now we are discussing a tangent topic that sprang out of that), and its a point about philosophy of science, not reality.
It's entirely possible its not true because the universe doesn't have to be sensible, but if it ISNT true, I would suggest the next step isn't a physics experiment but picking up a bible and praying to god. Cos now shits gone nuts.
I have not yet acknowledged this because I've been sidetracked with other things, so I'm making it very clear to you that this point of yours about models not needing to match reality is true, I agree, and we are all good on that. I regularly argue that in similar topics and I learnt this in my science degree, which I take very seriously. I actually just thought energy mass equivalence had been shown before. If this isn't true, then that's the mistake I'm making here: my knowledge is wrong.
Mass creation from energy has not been observed (yet)…
Buut I may be a few months out of date.
https://www.bnl.gov/newsroom/news.php?a=119023
Baryons are still believed to be conserved as far as I know though
It's a simulation of a type 1a supernova. It's not a core-collapse Type II supernova which is what you're probably thinking of.
The 1933 experiment of gamma rays entering a cloud chamber, interacting, and producing electron-positron pairs is energy to mass conversion. A massless bit of energy went in and two particles with mass were produced.
The experiment you linked is about the Breit–Wheeler process where two photons collide to produce an electron-positron pair. It's a more direct mechanism for energy to mass conversion than the cloud chamber experiment (and others), but far more difficult to achieve as photons normally do not interact.
Two different mechanisms. Both demonstrate energy to mass conversion.
A thing I noticed in that invariant mass link is that two photons not travelling in parallel can have invariant mass.
Is this the same process? Do they have to be close? Do they have to collide? Trying to wrap my head around it.
new Sabine just dropped, and it touches on some of the recent discussion
Your mom.
The distinction is that a 1a occurs when a white dwarf siphons mass from the envelope of a larger star, and gains sufficient mass to restart fusion and explodes. They're the least energetic type of supernova, but also the most common. Also, because they always happen at a very specific mass limit and thus have a very narrow range of brightness and energy, they're extremely useful for determining intergalactic distances.
The invariant mass (rest mass) of a system of non-parallel photons exists regardless of whether they interact or not. It's a consequence of photons having momentum and a system of multiple non-parallel photons not having a rest frame where all photons are non-moving.
One thing I forgot to mention in my previous reply as it relates to what kicked off this discussion is that while you would likely have pair creation energy to mass conversion occur when trying to create a Kugelblitz from all the photons flying around, that is just a side effect. A Kugelblitz is not formed because you are creating particles with mass from massless photons. It is formed because the concentration of energy in a limited area as described by the stress-energy tensor of general relativity causes enough spacetime curvature to form an event horizon. GR doesn't need "real" mass to produce that curvature.
Still absolutely terrifying to me! Like I know it's not really different from what we consider a normal black hole, but somehow the concept of creating a black hole without feeding it ridiculous amounts of mass is terrifying.
Doesn’t observing a black hole imply creation of mass from energy? If light can be captured by a black hole event horizon (which presumably it can) then energy is being converted to mass.
Edit: also some nuclear reactions such as neutron capture in elements heavier than iron should include conversion of energy into small amounts of mass.
We don't know what happens to the light inside an event horizon (we don't know what happens to anything inside a black hole for real, its all just educated guesstimates and desperate attempts to create a solution that doesn't break the universe) and the hole you see in pictures of black holes is significantly larger than the actual event horizon, because light is bent around and captured by the black hole far outside of the event horizon.
So we only ever see light that hasn't been caught.
The Monster Baru Cormorant - Seth Dickinson
Steam: Korvalain
I think you need to explain for precepts here: what is the reinforcing wave meant to be?
The wavefunction of solid matter is generally tiny - this is why electron microscopes are a thing, because an accelerated electron has a much shorter wavelength (and much better diffraction limit) then electromagnetic radiation.
So there are no cosmic scale matter-wavefunctions hanging about.
There's also other problems with the idea: if matter were periodically gaining a lot more gravitational mass, then we'd see the effects quite clearly because that would make a big change in behavior, and regular matter we are very good at seeing.
If it helps the amount of energy is so gigantic and concentrated that we don't really know of any conditions in our universe that would result in one
Eh... it's density, right?
Maybe, if you get it to converge into a wave length of the light, you only need enough energy to produce a back hole nanometers in circumference.
It would evaporate very quickly, and well... that kinda goes out the window because we don't really have a theory of gravity for stuff on that scale.
Otherwise you're atuck trying to figure out if a gama ray burst can get gravitationally lensed, by a black hole, with no accreditation disk, can focus the energy tight enough. But.... maybe there are numbers you can plug into that were it works?
Gravitational lensing has a similar limit to a glass lens. What's the hottest temperature you can make with a lens in sunlight? If you're in a vacuum, about the same temperature as the surface of the sun, because that image you're making of the sun is composed of the light from the radial diameter of the magnifying lens, and the "point" you focus on is actually the size as the same radial diameter section of the surface of the sun, not a true point.
With a perfect gravitational lens, you can focus some of the energy of an event, but the focal point peaks at about the same energy density as the event itself.
to do that with light is E = 6x10²⁴kg x c² in photons concentrated into a small enough point to collapse in on itself
and we'd not have any chance of noticing the result unless it were extremely close to us
how that would possibly be able to happen in nature seems to stretch beyond belief but it is an interesting thing the math says is possible
possible doesn't mean it exists
what have i done to deserve this
The problem is also that quantum gravity almost certainly gets involved in this sort of thing, and we have no theory of it.
At the time I thought "that's cool" but didn't really understand what they meant by dimensions. Which dimensions?
I just got reminded of it, so uh, anyone here know?
It's the dimension without shrimp.
A dimension without lemons.
Anyway: that was probably string theory? Iirc that one involves there being multiple additional dimensions on top of time xyz but they're set up in such a way we never see them.
Because the string math requires they exist or it doesn't work out right. To date as far as I know no one has figured out how to test this.
https://imagine.gsfc.nasa.gov/science/questions/superstring.html
That's a lot less interesting.
well because
look it just does okay no more questions
In that version, the big bang was two branes colliding, and possibly the one our universe hit is a couple millimetres away from us on that extra axis.
However, tests of brane theory predictions have put some pretty hard constraints on their viability.