I have encountered this sentence:
Science can explain how gravity works between two objects, but why
should it be based on the exact equations we find rather than others?
In fact, why should gravity exist at all? Answering the “why”
questions sometimes stretches necessity to its limits.
What is the meaning of the phrase : stretches necessity to its limits. what is the meaning of stretch something to its limit?
Best Answer
At least a couple of paragraphs before and after your cited excerpt are primarily preoccupied with defining "necessity" in this context. What's being metaphorically "stretched" is the philosophical concept of "necessity". Some theorists believe God is a necessary component of reality, for example, and others think there are multiple universes, not all of which even have gravity. In order to cover extremes like that, the concept of "necessity" has to be metaphorically stretched so far it breaks (its usefulness as a way of thinking about reality is broken, no longer functions adequately)
He's talking about the fact that we live in a fine-tuned Universe. As Hawking says, The remarkable fact is that the values of [the universal constants] seem to have been very finely adjusted to make possible the development of life so people may say it's a "necessity" that the strong nuclear force, for example, is within a percentage or so of the actual value we observe (if not, we couldn't exist in order to observe the value at all). But the concept of "necessity" becomes very imprecise (we're metaphorically stretching the definition) if we invoke the multiverse.