That is my question.
I don't mean 'created by humans', I mean 'do we know of any instance when matter/energy was created?'
I know a law of thermodynamics says that energy cannot be destroyed or created. Does that mean, that from what we have observed so far, energy seem to have always existed? Or does it mean that just we cannot create energy, just transfer and convert it, and that energy can be created in ways out of our power?
Not really. The phrase "what's there is there" provides a decent descriptor for it. I can't imagine how you'd "create" energy anyway. Pretty much everything must be derived from pre-existing materials, going back to the thermo thing.
I mean 'do we know of any instance when matter/energy was created?'
It depends. If you mean locally, then no. Energy is conserved everywhere in the sense that if one looks closely at any region of space and time (duration), no energy is created there. The law of conservation of energy is really a local statement: for every infinitesimal region of spacetime, as much energy flows out as flows in. It has never been violated.
If you mean globally, i.e., "if look at the total energy of the universe, can it change in time?" the the answer to that is either "sort of" or "you can't do that." It's not that humans can't carry out the experiment to measure a "total energy" of the universe; it's rather that there may be no coherent way to define it in the first place (and as far as I'm aware of, when there is, it's always conserved).
On the other hand, cosmic inflation has the property of expanding space while maintaining constant energy density. In some sense, one can view it as 'creating energy', although some would disagree, preferring to say that gravitational energy balances out the change. There is some room for a disagreement because there are some issues of how to meaningfully define 'gravitational energy'.
So energy is like the most basic....'thing'?
Most certainly not. That energy gets singled out for that sort of metaphysical finagling is actually a pet peeve of mine. Energy is just one conserved current due to time symmetry of a physical system; it's not like it's the only conservation law (heck, it's possible to design a system to have infinitely many conserved quantities). From the perspective of general relativity, energy is just one degree of freedom of spacetime curvature.
Energy/matter (essentially the same thing as you seem already aware of) simply, ultimately, and infinitely exists. It cannot be created and cannot be destroyed, because attempting to destroy any matter would create energy (nuclear fission/fusion), and attempting to absorb energy via matter would really do nothing to the energy other than change its form, into, say, chemical bonds.
Likewise, and for the same reasons, you cannot spontaneously form energy/matter, since there would be nothing to form it from. No raw material, so to speak.
Statistically speaking, the chances are near-immeasurably low, but it happens all the time in nature, just usually with as much being destroyed as created. At the subatomic level it's really impossible to tell if something is here, there, left, right, up, down, before, after, or if it exists at all, and particles are always popping in and out of existance, just with such a balance that no one notices it. I suppose it must happen every now and then that one particle will dissappear and two will replace it, but at that level we wouldn't be able to measure, and so couldn't notice, and probably wouldn't care. Going by pure statistics, it's possible for every atom in the universe to pop out of existance simultaniously, with none of them returning. It's also possible that another big bang could randomly appear in the universe that is already here, filling it with twice as much matter and energy (2x infinity though does seem like a bit of a logic error). This can be derived from what we have observed. Though we assume there is some grand scheme to things that is hyperdimensional and just beyond our reach, it's also possible that everything is ruled by pure chance. To have anywhere near a likely chance though, you would have to wait longer than the theoretical lifespan of the universe, or at least as long as it has been since the big bang.
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The awesome thing is no, niether matter nor energy are created. And they are not destroyed. A finite level of matter and energy would require some seriously a**l recycling habits. The rock cycle, the water cycle. Matter and energy in its various forms are used, exhausted, and then broken down and reused again. Nothing is wasted. The truly amazing thing though is that it has always been here, and it always will be. Matter has always been, and it's just such a radical thought, the idea that something was never created, but simply has always been in existance. ANd it always will be.
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No, new energy cannot be created. Everything is made of materials that existed before it. Basically the matter in our universe came from a different type of energy. The only way existence is possible would be if time and matter has always existed. If it didn't always exist, then it would of been impossible for the energy to pop out of nowhere and create time, because what has always existed needs no creation.
In the Big Bang? I was always confused as to where matter/energy goes in a black hole too...
i no that the matter, at least, gets ripped apart down to the atom and placed in the supercondenced core that is sooo dence its gravity can absorb light and not let it go. as for the energy, so far we no it can enter the event horizon and not come back out, but i cant even guess what would happen to it once inside.