PhysicsTo create a wormhole that doesn't collapse, you need exotic matter Making a wormhole that a human could theoretically travel through would require an upside-down universe and negative energy Features
PhysicsWill time ever end? The answer lies in the death throes of the cosmos The universe might meet its end in a big freeze, a big crunch, or a big rip. But whether time ends with the demise of the cosmos depends on whether it is even real after all Features