Schrödinger's cat is a thought experiment. The cat is supposed to be real in the experiment. The experiment is supposed to be seen as silly.
People can reason through the math at the level of particles and logically there should be no reason why the same quantum logic wouldn't apply to larger systems. So if a bunch of particles can be entangled and if on observation (unrelated to consciousness) the wavefunction collapses (and thereby fully determines reality) then the same should be able to happen with a particle and a more complex system, such as a real live cat. After all, what is a cat except for a bunch of particles? This means the cat is literally both alive and dead until the superposition resolves.
The problem is that philosophers have sometimes abused this apparent paradox (both alive and dead!?) as some sort of Deep Mystery of quantum physics. It's not a deep mystery at all. It's just something that illustrates that if you take the Copenhagen interpretation literally then you have to bite the bullet and admit that a cat (or a human, etc) can be both alive and dead at the same time. Not just seemingly so, but actually so in reality. As that's the only thing that's consistent with the small scale quantum experiments. Schrödinger came up with this thought experiment because he realized the implications of the Copenhagen interpretation and concluded the implications were absurd.
If you're not willing to bite that bullet (and most quantum physicists nowadays aren't) then you have to look at other possibilities. For instance that the world splits and that in one world the cat is alive and in the other the cat is dead. In one world you'll observe the cat being alive and in the other world you observe the cat as dead. Both worlds are equally real and in both worlds you have the sensation of being in the only real world.
(I only have an elementary understanding of QM)
If you're not willing to bite that bullet (and most quantum physicists nowadays aren't)
Incorrect. Most physicists today would tell you that schodinger's cat is |alive>+|dead>.
If the world simply "splits," then you've got a hidden-variable theory, which has been ruled out by Bell's inequality measurements. Instead what happens is more complicated, and is mathematically equivalent to one-world quantum mechanics.
Suppose you believe in the Copenhagen interpretation of quantum mechanics. Schroedinger puts his cat in a box, with a device that has a 50% chance of releasing a deathly poisonous gas. He will then open the box, and observe a live or dead cat, collapsing that waveform.
But Schroedinger's cat is lazy, and spends most of its time sleeping. Schroedinger is a pessimist, or else an optimist who hates cats; and so he mistakes a sleeping cat for a dead cat with probability P(M) > 0, but never mistakes a dead cat for a living cat.
So if the cat is dead with probability P(D) >= .5, Schroedinger observes a dead cat with probability P(D) + P(M)(1-P(D)).
If observing a dead cat causes the waveform to collapse such that the cat is dead, then P(D) = P(D) + P(M)(1-P(D)). This is possible only if P(D) = 1.
If you don't say that only conscious agents can collapse waveforms, then you have to agree that something in the box collapses the waveform as seen from inside the box, while it's still uncollapsed to Schroedinger. And Schroedinger's opening the box collapses that waveform for him; but it is still uncollapsed for someone outside the room. This seems like it might be equivalent to many worlds - all possibilities already exist; you just haven't chosen which one you're going to access until you open the box.
But if you do say that only conscious agents can collapse waveforms, then it's something about their mental processes that does the collapsing. This could mean their beliefs matter. And then, the cat is always dead.
ADDED: People. Read the entire post before responding. I am not claiming that the cat is always dead. I am not claiming that consciousness collapses waveforms. I am claiming that there are only 2 known alternatives:
If you can't produce another alternative, and you don't believe in many-worlds, you owe me an upvote.
Finally, this post is supposed to be fun! You are crushing all whimsy and playfulness on LessWrong when you pile downvotes like bricks on anything playful because it does not provide a complete and satisfactory resolution.