If atoms were like the solar system, all of the electron orbits would lose energy and decay by emitting electromagnetic radiation.
The same type of decay does occur in the solar system as the planets emit gravitational radiation, but the decay rate is so miniscule we can’t really detect it.
Could you explain what you mean by “emitting gravitational radiation”? Gravity is how we perceive distortions in spacetime, the strength of which being determined by the mass of the objects. I understand that orbits can “decay”, but that is not the same as radioactive decay.
General relativity is famously difficult to understand, and I don’t claim to fully understand it, so I’m going to fall back to the famous rubber sheet model.
Imagine the Earth in empty space. The mass of the Earth causes spacetime curvature that extends outward away from the Earth. However, if you look a single little patch of spacetime at some distance, say, 1000 km away, that little patch doesn’t know that it has to be curved because the Earth is 1000 km away. It doesn’t know where the Earth is. It just knows that its neighboring patch is a little bit more curved in the direction that leads to Earth, and its other neighbor is a little bit less curved going away from Earth. This essentially restates the principle of locality: all physics is local physics, and there is no spooky action at a distance.
Now imagine that the Earth moves by some small distance dx in a small time dt. Going back to our little patch of spacetime, it doesn’t know that the Earth moved. So how does it change its curvature to match the new position of the Earth? It changes when its neighbors change. When the Earth moves, the spacetime immediately near the Earth stretches and bends first, then spacetime a little further away, and so on and so on. This process doesn’t happen instantaneously; it takes time for changes to propagate to longer distances. The theory predicts that disturbances and ripples will propagate via waves, called gravitational waves, and that these waves travel at the same speed of light as electromagnetic waves.
Notice I called these spacetime waves “gravitational waves.” It is common to use the term “gravity waves” for typical water waves, of the kind you might see at the beach. Those are not the same type of wave.
Now let’s talk about energy. The Earth in the solar system has some energy, including translational and rotational kinetic energy, gravitational potential energy as it sits in the Sun’s gravity well, and of course its own thermal energy and rest mass. Waves have the ability to transport energy from one location to another without transporting matter, mass, or electric charge. Spacetime waves are not any different. Because the Earth is moving in a periodic motion, it produces a periodic spacetime wave that propagates outward away from the solar system, and that spacetime wave carries some amount of energy away from the solar system. Where does that energy come from? It comes from the Earth, mainly from the Earth’s kinetic energy.
So the story is that the gravitational waves are very, very, very slightly causing the Earth to slow down in its orbit. And following the laws of orbital mechanics, this causes the Earth to fall closer to the Sun. The result is that over the long term, the radius of the Earth’s orbit gets smaller. Alternatively, the Earth’s circular orbit is an illusion, and it’s actually spiraling inward on a very, very, tightly packed spiral. That’s what I meant by “orbital decay.”
I find it hard to overstate just how small this gravitational radiation effect is for a typical solar system situation. We have an observatory called LIGO that can detect gravitational waves. It can measure a variation in distance of a tunnel of several kilometers down to well less than a single proton diameter. (Remember, this is trying to detect disturbances in space and time itself). Even still, it is only able to detect gravitational waves from the most powerful kinds of gravitational events–mergers of black holes and the like.
Essentially: Spacetime is very “stiff” and gravity is very weak.
They weren’t talking about radioactive decay, electrons are stable. They were talking about electrically charged particles emitting electromagnetic radiation when accelerated. (Circular movement is accelerated, see centripetal force) Since they use energy for this, they would very quickly fall into the nucleus (if I remember correctly, in around 10^-14 s).
Bodies with mass also emit gravitational waves when accelerated, but much less.
Electrons do orbit like planets in the solar system however they’re also waves. Which is what gives the set radii they can orbit at and keeps it all stable. The orbits can and do change due to the emission or absorption of certain quanta of radiation.
So saying like is fine. It’s not an exact description but more of a simile to help understanding. They do orbit like a solar system. Saying electrons orbit the same as a solar system would be incorrect. That’s when the maths doesn’t work and the electrons orbit would decay.
that is not what i’ve learned, afaik electrons do not orbit with any sort of movement, and in fact talking about positions and movements at all on such a small scale is misleading.
What i’ve learned is that electrons exist as a probability cloud, with a certain chance to observe them in any given position around the atom depending on the orbital and the amount of other electrons.
Comparing it to gravitational orbits is just basically entirely incorrect, and certainly isn’t going to help someone pass advanced physics classes.
i’m not sure why you think the uncertainty principle is a “gotcha”, it specifically states that you can’t know both the position and momentum of a particle and thus explicitly contradicts your claim that we’d know everything about them because we know their mass.
I can’t be arsed to write out a whole scientific paper here so i’ll just link to the probability cloud model of orbitals and hope you can make sense of that.
You specifically said “electrons do not orbit with any kind of movement”
So by your own argument they’re not moving. We know the mass. So if we find one by your logic we know everything about it.
Yes that is the probability cloud model well done.
However my point again. You seem to think saying this renders the simile of planetary orbit obsolete. It doesn’t it’s a simile. It’s a way of explaining something that doesn’t have to exactly explain it.
If someone said “that fell on my head like a ton of bricks” would you go and examine the object and check it was exactly a ton of bricks or that it exactly exhibited the properties of a ton of bricks?
Or perhaps would you understand something from that about what had happened to them.
The passage of time is always consistent for the observer, in that a clock next to them will always tick at the same interval. The tidal wave planet from Interstellar is a good example of this, in that only a short time had elapsed for the people on the surface, but back home on earth over 20 years went by.
-Edited, didnt explain correcty the first time
If atoms were like the solar system, all of the electron orbits would lose energy and decay by emitting electromagnetic radiation.
The same type of decay does occur in the solar system as the planets emit gravitational radiation, but the decay rate is so miniscule we can’t really detect it.
Could you explain what you mean by “emitting gravitational radiation”? Gravity is how we perceive distortions in spacetime, the strength of which being determined by the mass of the objects. I understand that orbits can “decay”, but that is not the same as radioactive decay.
General relativity is famously difficult to understand, and I don’t claim to fully understand it, so I’m going to fall back to the famous rubber sheet model.
Imagine the Earth in empty space. The mass of the Earth causes spacetime curvature that extends outward away from the Earth. However, if you look a single little patch of spacetime at some distance, say, 1000 km away, that little patch doesn’t know that it has to be curved because the Earth is 1000 km away. It doesn’t know where the Earth is. It just knows that its neighboring patch is a little bit more curved in the direction that leads to Earth, and its other neighbor is a little bit less curved going away from Earth. This essentially restates the principle of locality: all physics is local physics, and there is no spooky action at a distance.
Now imagine that the Earth moves by some small distance dx in a small time dt. Going back to our little patch of spacetime, it doesn’t know that the Earth moved. So how does it change its curvature to match the new position of the Earth? It changes when its neighbors change. When the Earth moves, the spacetime immediately near the Earth stretches and bends first, then spacetime a little further away, and so on and so on. This process doesn’t happen instantaneously; it takes time for changes to propagate to longer distances. The theory predicts that disturbances and ripples will propagate via waves, called gravitational waves, and that these waves travel at the same speed of light as electromagnetic waves.
Notice I called these spacetime waves “gravitational waves.” It is common to use the term “gravity waves” for typical water waves, of the kind you might see at the beach. Those are not the same type of wave.
Now let’s talk about energy. The Earth in the solar system has some energy, including translational and rotational kinetic energy, gravitational potential energy as it sits in the Sun’s gravity well, and of course its own thermal energy and rest mass. Waves have the ability to transport energy from one location to another without transporting matter, mass, or electric charge. Spacetime waves are not any different. Because the Earth is moving in a periodic motion, it produces a periodic spacetime wave that propagates outward away from the solar system, and that spacetime wave carries some amount of energy away from the solar system. Where does that energy come from? It comes from the Earth, mainly from the Earth’s kinetic energy.
So the story is that the gravitational waves are very, very, very slightly causing the Earth to slow down in its orbit. And following the laws of orbital mechanics, this causes the Earth to fall closer to the Sun. The result is that over the long term, the radius of the Earth’s orbit gets smaller. Alternatively, the Earth’s circular orbit is an illusion, and it’s actually spiraling inward on a very, very, tightly packed spiral. That’s what I meant by “orbital decay.”
I find it hard to overstate just how small this gravitational radiation effect is for a typical solar system situation. We have an observatory called LIGO that can detect gravitational waves. It can measure a variation in distance of a tunnel of several kilometers down to well less than a single proton diameter. (Remember, this is trying to detect disturbances in space and time itself). Even still, it is only able to detect gravitational waves from the most powerful kinds of gravitational events–mergers of black holes and the like.
Essentially: Spacetime is very “stiff” and gravity is very weak.
That was a great read, thank you
Thank you very much for the thought out explanation, i think im beginning to grasp the concept. To summarize to make sure:
So the comparison to atoms releasing EM energy is a bit more apt then I initially thought. Thanks again!
They weren’t talking about radioactive decay, electrons are stable. They were talking about electrically charged particles emitting electromagnetic radiation when accelerated. (Circular movement is accelerated, see centripetal force) Since they use energy for this, they would very quickly fall into the nucleus (if I remember correctly, in around 10^-14 s).
Bodies with mass also emit gravitational waves when accelerated, but much less.
Electrons do orbit like planets in the solar system however they’re also waves. Which is what gives the set radii they can orbit at and keeps it all stable. The orbits can and do change due to the emission or absorption of certain quanta of radiation.
So saying like is fine. It’s not an exact description but more of a simile to help understanding. They do orbit like a solar system. Saying electrons orbit the same as a solar system would be incorrect. That’s when the maths doesn’t work and the electrons orbit would decay.
that is not what i’ve learned, afaik electrons do not orbit with any sort of movement, and in fact talking about positions and movements at all on such a small scale is misleading.
What i’ve learned is that electrons exist as a probability cloud, with a certain chance to observe them in any given position around the atom depending on the orbital and the amount of other electrons.
Comparing it to gravitational orbits is just basically entirely incorrect, and certainly isn’t going to help someone pass advanced physics classes.
If they don’t orbit with any kind of movement then what does that say about Heisenberg’s uncertainty principle?
We know their mass. So once observed we would know everything about them.
Unless your saying they just some how jump from one random point in that probability cloud to another?
i’m not sure why you think the uncertainty principle is a “gotcha”, it specifically states that you can’t know both the position and momentum of a particle and thus explicitly contradicts your claim that we’d know everything about them because we know their mass.
I can’t be arsed to write out a whole scientific paper here so i’ll just link to the probability cloud model of orbitals and hope you can make sense of that.
You specifically said “electrons do not orbit with any kind of movement”
So by your own argument they’re not moving. We know the mass. So if we find one by your logic we know everything about it.
Yes that is the probability cloud model well done.
However my point again. You seem to think saying this renders the simile of planetary orbit obsolete. It doesn’t it’s a simile. It’s a way of explaining something that doesn’t have to exactly explain it.
If someone said “that fell on my head like a ton of bricks” would you go and examine the object and check it was exactly a ton of bricks or that it exactly exhibited the properties of a ton of bricks?
Or perhaps would you understand something from that about what had happened to them.
You may find this useful. https://en.m.wikipedia.org/wiki/Simile
Ok, hear me out for curiosity sake. What happens if you slow down time to magnitudes less then you can observe?
The passage of time is always consistent for the observer, in that a clock next to them will always tick at the same interval. The tidal wave planet from Interstellar is a good example of this, in that only a short time had elapsed for the people on the surface, but back home on earth over 20 years went by. -Edited, didnt explain correcty the first time