Maybe I’m misinformed about this. But I was always told matter cannot be destroyed or created. But I have been told space is constantly expanding. Is this expansion of space not made up of “matter”? Where does it come from?
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Hold up two fingers next to each other.
Move them away from each other.
Did you create or destroy any fingers?
You could think of it like inflating a balloon. Although the balloon appears bigger it hasn’t gained any matter, it just stretched.
There’s a theory that the end of our universe could be caused by expansion, basically space would stretch so much that molecules and atoms would be ripped apart.
You have cake. You cut the cake in half. You take both halves apart.
You have the same matter, but now it occupies more space.
Space is expanding, as in spreading apart. Not adding more mas
Mass is Energy, you can change between the two. The “edge” of the universe is unperceiveable though if one does exist it’s just how far something travelling at the universal speed limit (also known as the speed of light) could reach if it existed since the start of time, since space is the lack of stuff something must have travelled through it for it to be emptied.
There is actually a recent theory that uses some very complicated maths to re-examine what we have seen and states that the universe isn’t actually expanding, we are just seeing what is as far as I understood particles becoming old. So we may assume they are actually moving away from us when it’s could be that they are just different from particles much closer to us.
I have suspicion that the expanding nature of the universe is due to the spin of galaxies. There’s a right hand rule which says that if the fingers are lined up with the spin of an object, a thrust is created in the (thumb) at a 90 degree angle to the plane of rotation.
Picture Your right hand holding a bottle, fingers together & wrapped around the bottle, with thumb pointed up, perpendicular to fingers. This acceleration force is what keeps gyroscopes standing.
At the cosmic scale, energy conservation doesn’t hold true. This is exactly because of (or related to) the expansion of the universe.
Dark energy makes up 68% of all matter/energy in the universe and it’s quantity is directly related to the size of space. So, as the universe expands there is more dark energy in the universe and hence more total energy.
Another way to reason about it is with Noether’s theorem, which states that every conserved quantity has a corresponding symmetry. For energy, this is time symmetry. With the expansion of the universe we no longer have time symmetry at the cosmic scale, which means we also no longer have energy conservation.
I should note that dark energy is a frontier of modern physics. That is to say that it’s not well understood. So this explanation is based on current understanding, which is known to be incomplete.
Think of it like a container of water that can magically expand or shrink. You decide to add a set amount of water into it. You also decide that you want the container to expand. While the container expands, it’s internal volume increases, while the amount of water in it remains the same. This is an extreme way to simplify the expansion of our universe. While the volume of matter our universe can contain increases, the amount of matter in it remains the same(it actually does not, the amount of matter in the universe can change over time due to the Information Paradox, Hawking Radiation and Black Holes). As to how it expands, there is an unknown force causing the universe not just to expand, but to also cause this expansion to speed up. Just how your car needs the chemical energy of fuel to accelerate, there is an energy accelerating the expansion of the universe. This unknown energy is called “dark energy” (“Dark”, because we so far have not been able to measure or detect this unknown force).
Things aren’t getting bigger. They are moving further apart. Galaxies all more or less fly outward from the center of the universe, because everything is debris flying away from the big bang.
Well this is often confusing based on semantics. Sometimes when ppl talk about expansion from big bang they are talking about how far the stuff that was in the big bang has spread since the “bang”. We think we know how long ago said bang occurred, 13.8 billion years. Nothing new has been created in those 13.8 billion years, it is all just getting more spread out, both matter and heat. Now why does it constantly expand? It is possible that it wont continue to expand. Scientists theorize how much force was involved in the bang. If the total weight of all this stuff is heavy enough then the effects of gravity will slow the expansion to zero and then contract. If the total weight is lower than some number then the force of the bang will go forever. Scientist believe they know what this target weight is.
Thats as close to five year old i can get atm.
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