Deferrals require you to re-apply, which means you might not get in again.

That depends on the school. Many do not require you to re-apply.

Sure, and the foundational breakthroughs in physics has allowed us to spend more time thinking about social progress and technology. The two are tightly coupled.

I can't even begin to calculate how many hours of humanity has been saved by the breakthroughs and technology that physics has bequeathed us.