Science serves as a powerful tool for unlocking the mysteries of the universe, but understanding its limitations is essential for its effective application. There are occasions where I have used the handle of a knife as a hammer (锤子), but the result would have been better if I’d had a more suitable tool at hand. As far as science goes, it is really good at testing things that are testable, but not so for those that are not.
We can do, and have done, an impressive amount with our brains. But there are limits. Sometimes these limits go away if we keep at it for long enough — we just need better facilities and experiments to get the answer. Breaking new ground in modern science this way can be costly. Next-generation supercomputers or incredibly large telescopes are expensive, yet these may be required to find answers to some of the unsolved mysteries of the universe.
Sometimes the limits we encounter in trying to unlock the nature of the universe are cognitive (认知的). Think about this: human DNA is only about 1.2 percent different from that of chimps (黑猩猩). Chimps are smart, no question. But could you teach them advanced mathematics? What if our DNA were another 1.2 percent further evolved than it is? What might our brains be capable of then? The level of abstract thinking might be unimaginable.
Sometimes the limits we hit are fundamental. There are laws of nature we may never be able to understand, however advanced our brains might become. There are experiments we might never be able to perform. We may never be able to test what caused the universe to be created, and what caused the cause of the universe being created. This is where science may never break through.
For something to be considered scientific, it must, by definition, be testable. There is a problem here: it may not need to be testable right now, but it must be testable at some point in the future by experiment. If an idea is untestable, that doesn’t mean it is wrong. It means it is untestable for now. These untestable ideas also happen to be some of the most interesting ones, probably because they’ve puzzled humanity for centuries.

Why does the author mention “knife” and “hammer” in Paragraph 1?