I've been accelerating away from earth at 1g for 43 years, and haven't gotten nearly that far

"I remember when I left earth, must have been around 7 years ago"
"Captain, you have been on voyage for the last thousand years"

For the record at 99.7%(c) if a single grain of space dust hit the spaceship, the spaceship would literally undergo nuclear fission. All of the materials would turn into a ball of plasma and gamma radiation.

0:17 my first kerbal space program rocket

I never thought about the fact you'd be able to see the CMB. That's really cool. Great video.

8:08 One way to phrase it is "We are not capped by the speed of light. Only other people are."

On the edge of observable YT, I found a video with proper physics.

Maths equations

“Indeed sir, indeed. Are there more pictures sir?”

I laughed too hard at the first rocket falling over and exploding 😂

To put it in perspective, it took over 5 days for Artemis 2 to get to the moon, and only 15 hours for this sim to get to MARS.

I always wanted to see this particular thought experiment....

4:00 "At this point [near Neptune] you register more than a minute difference [in the ship clock] with a clock on Earth." - so the proper time s (on the ship clock), the Earth time t, and the distance r satisfy r² + s² = t², if r is rendered in light-speed units. The time difference is simply t - s = r²/(t + s), and Neptune is about 4 light-hours from Earth. Since t and s are both about 9 days and 2 hours (or 218 hours), then that comes out to 4²/(216 + 216) hours = 1/27 hour, which is about 2 minutes.

So you can't go anywhere in universe without time traveling into future related to Earth... Whata a fucked up universe we ended up in.

To maintain constant acceleration, you would have to keep increasing the rate you are adding energy into the ship.  Would you get to a point where you have put so much kinetic energy into your spaceship that it would form a black hole?

If you had indeed such a spaceship and flew the 2.2 million light-years to Andromeda, accelerating for the first half of the journey and then turning the ship around to decelerate with 1g during the second half, it would take only about 27 years in the frame of the ship. So, one could travel to the Andromeda Galaxy within a human lifetime, whereas in the frame of earth 2.2 Million years would pass.
To give some numbers: Time elapsed on earth   /     Velocity [% of c]    /     Time elapsed in the spaceship
1 years            /     72.4% of c          /      0.87 years
2 years            /     90.4% of c          /      1.42 years
5 years            /     98.3% of c          /      2.25 years
20 years          /     99.98% of c        /      3.55 years
100 years        /     99.99% of c        /       5.08 years
1000 years      /    99.9999% of c    /      7.28 years

So if you go fast enough, you see what looks like the big bang in reverse

And this is how you only age 8 years while over 4000 years have passed on earth . This is how you time travel .

The protons aren't the only problem.  All the blue-shifted light shifts into ultraviolet, then X-rays, then gamma rays.  So normal starlight would become invisible while bathing you in gamma rays.

The plot of Tau Zero by Poul Anderson is based on exactly this idea. Worthwile read if you like hard sci-fi.

Since the universe is expanding we won't actually reach the border of the observable part in 25 years.