> “the Universe sprang into existence last Thursday”
I have memories from before last Thursday; therefore, this claim would contradict what currently seems to be true. That's the best I can do. If you're a physicalist, you cannot deny this claim with certainty either: if electrical activity in the brain is truly the substrate of consciousness, then you have to admit to the possibility that you could be a brain in a vat, hooked up to some kind of world simulator.
> “I am the only entity that exists”
That would imply that I'm God. And I'm pretty sure I'm not God. Therefore, other conscious entities must exist.
> “Jupiter doesn’t actually exists, it merely appears to exist.”
To be is to be perceived, in my view. I don't think there's a meaningful distinction between the two.