“What is real? What can I know for certain?” Is this related to Rene Descartes’ “I think therefore I am” ?
Yes. Thus Nietzsche says:
“Fundamental certainty. - “I imagine” [“Ich stelle vor”], therefore there is a Being [ein Sein]: cogito, ergo est. - That I am this imagining Being, that imagining is an activity of the ego, is no longer certain: just as little is everything that I imagine. - The only Being that we know is the imagining Being. […] Characteristic of imagination is change, not motion: passing away and coming to be, and in imagining anything persistent is lacking. On the other hand, it posits two persisting things, it believes in the persistence of 1. an ego, 2. a content; this belief in persistence, in substance, i.e. in the remaining identical thereof with itself, is a contradiction with the imagination process itself. […] Inherently clear, however, is that imagining is nothing resting, nothing identical-with-itself, unchangeable: the Being therefore, which alone is guaranteed to us, is changing, not-identical-with itself, has connections [Beziehungen] (conditions, thinking must have a content, in order to be thinking). - This is the fundamental certainty about Being. But imagining predicates precisely the opposite of Being! But that does not mean that it is true! But maybe this predication of the opposite is only a condition of the existence of this kind of Being, of the imagining kind! That is to say: thinking would be impossible, if it did not fundamentally mistake the essence of esse [das Wesen des esse]: it must predicate substance and that which is identical [das Gleiche], because a cognition [ein Erkennen] of the completely fluent is impossible, it must impute properties to Being in order to exist. There need not be a subject or an object for imagination to be possible, but imagination must believe in both. - In short: that which thinking considers, must consider, to be the real, may be the opposite of that which is!”
[Nachlass.]
Let’s put it this way…if there wasn’t a human being on this planet, or in the entire universe, the universe would still exist. Sure, there wouldn’t be things labeled “trees,” or “sound,” or even “thought,” but the actual physical atoms of the universe would still remain in place.
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How would you know the universe(object) still exist if there’s no human being (subject) who can decide the reality of his surroundings?
Because the existence of atoms is not dependent on the existence of the consciousness defining it as an atom.
hey sawelios! I liked ur response a lot.
but I didn’t understan it very well lol…
did you mean that Nietzsche says that we can be absolutely certain that imagination exists?.
I thought Nietzsche didn’t believe in absolutes at all. 
you can deny everything if you want, question everything, and that is fine, but what purpose does that serve for real life application of your life and or goals etc etc?
How do you know?
As you can see, Nietzsche did believe in an absolute: namely, in the existence of something, at least. And he thought that we could say at least two things about that something with certainty: 1. that that something was changing; 2. that it needed the idea of something unchanging. This belief is grounded in experience. Experience tells us that something exists; that this something is in flux; and that, in order for consciousness to exists (and it exists, that’s for sure), there must be at least the illusion of something beyond the flux, something unchanging.
That is not the question.
Are we headed towards Hume’s “…we can have no idea of anything…” territory?
oregonstate.edu/instruct/phl302/ … ment2.html
If so, Ddood, I recommend just changing the language to “I assert…” rather than “I know…”. I think that is is the soultion that makes the conflict go away! 
But that is my general statement to questions of this nature. The statement should sum up why I didn’t answer it.
hey sawelios, do u agree with Nietzsche on that?
Not very familiar with quantum physics,eh?
Can we know anything with any degree of certainty? I don’t think so. Being thinking beings that is where we live 95% of our existence, in thought. I don’t think we have any concept of the real with any degree of certainty at all.
I didn’t realize quantum physics proves that without humans, atoms wouldn’t exist.
Tautologies are all that can be know for certain.
The proof is here, and it is not just a simple sefl-referential paradox either:
If you “don’t think so,” then you are correct because you are not certain (A).
If you “do think so,” then you might not be correct because its not certain that you could be certain if it was certain…if you follow me. You could still be certain that you believe you were certain (B).
Nonetheless there is a case of “uncertainity” happening in either scenario. The epistemological activity, that is, the discourse in language happening here about this fact, will always produce a tautology in the end; the asking of the question means there is an answer or there is not an answer. It is either unknowable (A), or only believable (B). So the tautology is the self-evident truth of uncertainity that is revealed in the discourse-- “all dogs are dogs”…well yeah! Duh!
[size=75]But what is a dog?[/size]
[cue spooky music]
I spelled uncertainity like this on purpose because it is a non-first-person suspension of experience which allows me to posit the question without my falling victim to the problem of it.
The being-of-uncertainty is “Uncertainity”, which is a universal condition for mind.
You are real.
And all the infinite without and within that makes you real is also real.
You can know that you are real. Your heart must tell your mind that it is so (which it does), and your mind must accept the truth of it.
You can know that you are mortal.
You can know that there is no duplication – that is the miracle of identity.
That you can know for certain.
There’s a lot you can know for certain.
Simply trust your heart, repair from psychological damage that happens to you so that you can feel equally as well as think, and you will know much for certain, knowledge that baffles the mentally centered and affectively damaged.
No.
And Descartes was wrong.
The correct statement is: “I think, therefore we are”.
Yes, I do.