... New propulsion technologies are the key to interstellar travel. In order to perform meaningful exlporation beyond our solar system, we need radical new means of propulsion. Right now, we can barely travel in space at tiny fractions of 1% of the speed of light. Roundtrips to and from the nearest stars will take many hundreds of years. At that rate, everyone on earth who would care would be dead before a mission returned. Even at the speed of light, the nearest stars are years away, let alone other galaxies.
In essence, mankind is completely stranded on Earth (or at least in our solar sytem), until we can travel at many times the speed of light, without high energy (i.e. fuel, weight) costs. This will require a completely new physics.
The cost of ths effort is currently very small. I see keep at it - if we really want to explore beyond planet Earth.
Can't we just tweak a constant here and there?