So, we humans are made up of matter, consisting of vibrating...

So, we humans are made up of matter, consisting of vibrating strings of energy, that comprises less than 5% of the universe. Aliens are real and they may well be made up of dark matter and dark energy that comprises the other 95%, who knows?
We don't know what dark energy or dark matter are and whether string theory (vibrating strings) is a viable description of dark energy and matter as the jury is still out on this question.
Is dark energy even allowed in string theory?

In string theory, a paradigm shift could be imminent. In June, a team of string theorists from Harvard and Caltech published a conjecture which sounded revolutionary: string theory is said to be fundamentally incompatible with our current understanding of dark energy—but only with dark energy can we explain the accelerated expansion of our current universe.

"In string theory there are fields which could explain dark energy in a similar way – locally, they are in a state of minimal energy, but still their energy has a value greater than zero," explains Timm Wrase. "So these fields would provide the so-called dark energy, with which we could explain the accelerated expansion of the universe."

But Cumrun Vafa from Harvard University, one of the world's most renowned string theorists, published an article on June 25, raising many eyebrows. He suggested that such "bowl-shaped" fields of positive energy are not possible in string theory.

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As I said, the jury is still out.