Dimensions as told in quantum physics?

Question

What is past all of it? If you shot a bullet with the capability to travel an infinite distance into space, would it eventually hit something that made it stop? If it keeps going, where would it end? If it is infinite space, what is surrounding it? How can it be infinite?

Answer 1

It's great that you're using a thought experiment, they are the sort of things that geniuses like Einstein often used. However, as has already been pointed out, your experiment seems impractical. And if you imagined a bullet that was not affected by matter or any forces in the universe, well, it would be like it's not part of the universe at all.



Still, you imaginary bullet was not the key idea, what I think you're really interested in is if the universe has an end, and if so, what is after it's end.



These are great questions, and astronomers have studied this for years. The theory that currently seems most likely based on our understanding of physics and the measurements we have taken, is that the universe is infinite and has no end. (Note comparing the distance of two objects as far apart from each other as we can see in our best telescopes is a distance that really is *not* the same as the size of the universe.) Our best measurements are supporting the idea that the universe is not curved (though space-time is of course curved locally near massive objects like stars).



There are other theories about what the universe is like, one is a somewhat saddle shaped universe. While that model of the universe is curved, it is both infinite and unbounded. The other one is like a sphere (or as already pointed out, more like the surface of a hypersphere). This is the classic "balloon" idea of the universe many people are exposed to. It can be blown up showing it is expanding. But if you are trapped inside the surface of the balloon, if you moved in a straight line you would eventually come back to where you started. This model seems less likely based on astronomical observations made in the last decade.



So what's past all of it? Well, maybe there is nothing past it if it's truly infinite as most astronomers currently believe.



In principle, your bullet could keep going forever. In practice, it would likely run into something or come close enough to something that it's course would be altered even if it wasn't stopped.



But if the bullet kept going, it would just keep going without end.



If space is infinite, why do you think there has to be something surrounding it? Just imagine a Cartesian coordinate system. If you write it on paper, it is of course limited by the size of your paper. But as you know, such a system is meant to go on forever, and you're just modeling a small section of the overall with what you have written.



Or there maybe could be something around it. Imagine for a moment that our universe is two dimensional, a bit like a piece of paper, except the page has infinite height and width, but no thickness. Then you could imagine a whole set of other universes the same way, and have something like a book of these pages. Each page is surrounded by other pages, other universes. While not using this model, there are theories like the many worlds theory which could mean there are other universes out there.



You ask how can space be infinite? I ask why couldn't it be infinite? I mean we don't have a lot of other universes that we have seen and can compare ours too. We're in this universe, that's all we know about. Infinite may not seem intuitive to you since pretty much everything around us seems finite. But numbers are infinite, curves on graphs may be infinite, you even have an infinite number of points on a line segment of finite length. Infinity exists in mathematics, and most of our theories about the physical laws of the universe give us mathematical equations that describe things. So really, why couldn't the universe be infinite?



In my sources, I am including a few links you might find interesting. The first two are about the shape of the universe, while the last one is an old book that may help you understand three dimensional space better by the way it looks at a fictional two dimensional universe.

Answer 2

The bullet will not go on continiously. You are really exercising your imagination. The bullet will eventually come into the influence of gravity of some celestial object, where it will be made to fall on that body. That space is infinite is only one of the assumptions. One other assumption is that it curves upon itself as though a surface of a sphere, wherein it does not end and begin at all.



If you really have to imagine a body that will go on unstopped, it will be the "neutrino" that goes through planets, but then it may be captured by a blackhole, or gets transformed when it passes through the center of stars. But then it was not yet experimentable, because of unavailability of materials. Neutrinos, might be found, but stars, how will you handle it? You know how they are in Hollywood. hehe.

Answer 3

It is possible that our universe is curved so that the bullet would eventually come back to its starting point. Our space might be the 3-D hypersurface of a 4-D hypersphere. This topology would be finite but yet unbounded. The total mass in the universe determines if it is flat and infinite or curved and finte.

Answer 4

commencing back in historical Greece, it became into proposed that depend must be subdivided into smaller and smaller products, till you place out to a minimum of a few thing that should no longer be divided any further. Democratus called this smalles substance an "atom". we've found out plenty on account that then, yet we often settle for that there is a smallest particle someplace, besides the reality that technological know-how retains looking smaller ones time after time. Quantum physics has the comparable regulations approximately power. there's a smallest unit of power which Max Planck called a "quanta". the comparable way atoms of different components ahve different sized atoms, so too there are different "quanta" of power fo rdifferent ingredients. Taking it one step extra, and in case you decide on extra you ought to bypass on the internet, small quanta of power have twin residences, they might act like a particle (photons) or they might act like an electromagnetic wave. From right here on it gets complicated

Answer 5

technically if the light needs 100000 years to cross our galaxy, then the bullet will need, well.... much much more than that. so it will decompose before it can cross our galaxy.



about your question, nobody can or will understand that totally. that's why it is called infinite.

it's like numbers, if u count u will never arrive to the end...