This is my view, the primitive beings that we are, cannot imagine what is possible.
The universe so extensive, the light we see from some stars took up to billions of years to reach us. Those suns "stars" might not even exist anymore but we wouldn't know for millions or billions of years as the light is still traveling towards us.
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Yep. Welcome to astrophysics.
The sun could’ve blown up about nine minutes ago, and we’ll just find out here in a couple of seconds.
The very fact that there is a speed of light, that it is knowable, and that it bounds speed in normal space, is a big part of the discussion about alien life.
I dislike the analogy between the speed of sound and the speed of light. The two “barriers” are fundamentally different.
We broke the sound barrier. But we already knew that it could be broken. A 50 caliber rifle bullet, for example, went well beyond the speed of sound, and runs closer to Mach 3. So, Bell, when they designed the X-1, basically shaped it like a 50 caliber rifle bullet.
However, the speed of light is absolute because, well, Einstein was right. As you get to relativistic velocities, the mass of an object increases. And it simply increases to an infinite number at the actual speed of light, so even if we were to figure out a propulsion system they were able to push a spaceship to somewhere near that speed, it still couldn’t break the “barrier”.
And, because Newton was right, the propulsion is a big part of the problem with interstellar travel. In order to get a ship to 50% of velocity of light, you have to apply Newton‘s third law to the propellant, whatever that is. If the propellant goes out the back of the ship at the speed of light, then 50% of the mass of the ship has to be propellant in order to get the ship to 50% the speed of light.
However, you’re gonna need to slow down as you approach your destination. So, in order to get to 50% the speed of light, assuming that we have this incredible engine you’ll need 50% of the mass to be propellant, and then 50% of the remaining mass has to be propellant in order to bring the ship to a stop at our destination, so, 75% of the mass for a one-way trip.
But let’s talk about this incredible engine for a bit.
We need to talk about specific impulse. It’s basically a measure of how efficient the rocket is at turning mass into thrust, it has to do with the momentum. More here:
https://en.wikipedia.org/wiki/Specific_impulse
Right now, chemical rockets achieve a specific impulse of about 300. The Raptor on the Space-X Starship are up around 340. Some, like the J2 on the Saturn V, get close to 420 in a vacuum. Pretty good. Enough to get us to the Moon.
But to get to that incredible engine - the one that emits propellant at the speed of light - we need to be up around 30,000,000 for specific impulse. That’s a very, very long way from where we are, and even if we improve engine efficiency by a factor of 100,000, we still only get one way to another star with 75% fuel.
“We can bend space itself” via Alcubierre - well, perhaps, but you would have to convert nearly as much of the ship’s mass into pure energy to get there.
Interstellar travel is a physics problem, not an engineering one.