I’ve been reading on vacuum and it is super interesting, I have questions about it.
Vacuum is simply defined as a space that has zero matter in. Outer space isn’t even a true vacuum because of a few hydrogen atoms floating, and it’s very hard to create a true vacuum, and it was only created momentarily in labs. (Source: wiki)
Why is true vacuum so hard to create? What exactly makes the matter “want” to go into a empty space? What creates that pressure?
Can black holes be considered as permanent (or very long term) vacuum?
If we assume I have a small box filled with matter as usual. And I have the technology to filter out atoms/molecules one by one. At what point would it start showing vacuum properties?
I’m trying to wrap my head around why the lack of matter creates such a big difference and matter tries to fill it no matter what.
You must log in or register to comment.
"What exactly makes the matter “want” to go into a empty space? What creates that pressure? "
My understanding is only general, but I don’t think that it’s the case that matter wants to go to a vacuum, so much as that when there’s an imbalance of pressure (in this case between a pressured space and a vacuum), the pressure from the pressurised space has nothing to counter it, so matter is pushed in that direction.
Just as in a balloon the air is under more pressure than the air outside it - once there’s a way for it to escape, it just will do, until the pressure is equalised.
Thanks! Is it possible to have a non-pressured space that is not a vacuum?
The pressure of a non vacuum space would be generated by the gaseous molecules as they collide with the walls of their container.
My layman’s understanding is to get 0 pressure, you either need zero molecules, or the molecules can’t move. Which can only happen at 0K, theoretically.
This is true, in practical terms. The Ideal Gas Law gives us the equation PV=nRT, for gas pressure P, volume of container V, number of molecules n, R a constant that doesn’t matter here, and temperature T in Kelvin. The only other theoretical way to get 0 pressure would be to have infinite volume, but that’s hardly practical.
No, a vacuum is a lack of pressure. Anything that is at a lower pressure than the surrounding atmosphere will act the same as a vacuum.
Why is true vacuum so hard to create? What exactly makes the matter “want” to go into a empty space? What creates that pressure?
Imagine air atoms are like floating balls moving freely and constantly bumping into each other.
Suppose we have a container and we want to remove all air from it, what do we do?
We could poke a hole into this container and leave it. Over time air atoms inside the container will keep moving inside the container until they eventually - one by one - exit the hole. Problem with that approach is that there is also air atoms outside that would also enter the hole and you end up with roughly same concentration of air atoms inside and outside.
But lets say we somehow took that box and placed it into a perfect vacuum. Now air atoms inside the box will go outside but nothing from outside will go back to the box, that should make the box have perfect vacuum right?
Unfortunately not.
After the vast majority of atoms have exited the box, only very few atoms remain and they hardly collide with eachother anymore. Then their movement can be stabilized. For example one atom would keep moving in horizontal or vertical motion indefinitely and never ever get close to the hole. With no atoms to collide with it and change its path, it may never exist the box. That’s why its almost impossible to have perfect vacuum
Thank you!
So when it comes to true vacuum Quantum Field Theory proves that things are not as simple as they appear on our human macro level. Basically, there is no such thing as true vacuum in an absolute sense.
Ref: https://piped.video/watch?v=n6jAOV7bZ3Y
As far as things moving towards a vacuum, it is just stuff taking the path of least resistance at a simple level. Think of air and gases just like a slightly different liquid compared to water. Air and water flow in a very similar way. If you displace water by making a boat, the displaced water is always looking to get back into the displaced space. A vacuum is a similar displacement void that is fighting against everything else that wants to occupy that space.
Honestly, I’ve come across many things where I asked questions like this. I could be wrong, but it is likely that you are thinking of vacuum as some kind of state or force. It is not. Vacuum is the lack of baryonic matter. Maybe you have encountered this one before: “cold does not exist.” Cold is always a relevant thing and really it is a human invention to relate ideas. Nothing can be at true absolute zero in the universe as the motion of atoms is tied to time and entropy. So cold is always just the absence of heat or really, the absence of energy. Much the same, a vacuum is the absence of matter. The main thing that might move matter into a region of vacuum is gravity, or to a much lesser extent possibly magnetism depending on the properties of a gas.
As far as black holes, no vacuum can exist in a black hole. Once matter gets past the event horizon humans do not know any testable physics. Technically, as it is currently explained there is a singularity somewhere inside the event horizon. This singularity is the merging of both space and time. The merging is because you are being pulled at light speed the moment you pass the event horizon. You’re moving at the speed of time which makes physics break. Moving at the speed of time, means you are already merged with the singularity the moment you pass the event horizon, however the event horizon is larger than the singularity itself. The singularity, as we understand it, is time as much as it is space, literally “spacetime.” If it could be seen, theoretically, we could also see all of time on its surface…if it could be called a “surface.” A black hole is not really an object as much as it is a state.
This ref covers a lot of what I just said except for the very last point: https://piped.video/watch?v=cFslUSyfZPc
- Nature abhors a vacuum
Aristotle.
As the other person said, the universe just wants parity.
