If you are in a commercial airliner traveling at 500 miles per hour and you stand up in the aisle between seats and jump up in the air, why doesn’t the airplane move 500 mph under you and why don’t you crash toward the back of the plane? Why do you land in the same place you jumped from? Why when the flight attendant pours you coffee does the coffee stream not flow backwards toward the back of the plane?
The answers are because you and the coffee are moving with the airplane at the same speed – the same reason two people in the backseat of a moving car can toss a set of keys to each other without breaking the window at the back of the car.
Back on the ground, we are on Earth, moving with the earth. The air, the trees, the people, the pebbles on the ground, the coffee – all are moving with the planet. When you jump up or pour coffee it does what it does because everything is moving the same speed as the earth, just like in the airplane.
Spoiler alert – in the future there never will be artificial gravity – astronauts won’t be able to walk around in spaceships.
In the movies most spaceships like the Starship Enterprise employ a convenient technology they call “artificial gravity” to overcome this weightlessness problem. In a few movies they even rotate parts of the ship, though the part of the ship that rotates often has no relevance to the part of the space ship people are walking around in.
No matter. Walking around is a convenient way to avoid a big budget.
Weightlessness is a pesky little problem and we’ve become comfortable accepting that on spaceships of the future you’ll be solidly on the floor. Venture outside to fix anything and you’ll be weightless maybe (unless you use something they call “gravity boots”) but inside, put something on a table and it stays on the table. People won’t be weightless in spaceships in the future.
That’s why they call this stuff science fiction. There won’t be any artificial gravity and to the dismay of Kirk and Spock a spaceship that looks like their’s will have weightless people inside.
Another design, a real design, for a spaceship that would actually have “artificial gravity” is called the Von Braun spacewheel, and envisioned in movies wanting more realism. The Von Braun spacewheel looks like this contraption. Of course, it spins and as it does the occupants inside experience centripetal acceleration, also sometimes known as artificial gravity.
So why doesn’t NASA build one of these?
Well, along comes the real world, pushing Hollywood right outta there.
They don’t have the lifting power to get all the parts up there. It’s doubtful the Falcon-heavy will be utilized for such a project.
Assembly and then pressuring it inside are formidable obstacles. This is not impossible, but beyond available budgets.
Zero gravity laboratories, like the present International Space Station have taught us that research in microgravity environments is valuable.
With exercise, astronauts do just fine, so why bother?
Alas, we may send people to Mars one day, but those poor ol’ chaps will be weightless all the way, and exercise like they do on the ISS.
Did you know once in history it was decided that everything that ever will be invented has already been invented? It’s true.
“Charles H. Duell was the Commissioner of US patent office in 1899. Mr. Deull’s most famous attributed utterance is that ‘everything that can be invented has been invented.’ Most patent attorneys have also heard that the quote is apocryphal.” Quoted here.
That being said, they said it at the end of the nineteenth century, they will say it again! But alas, more things and technology will come along – not at a “stead” pace, as you ask, but in jerks, leaps and bounds, stalls and stumbles!
Great question, and you see, that’s what we mean when we say everything is relative. Your “speed” is always relative to something else. If you don’t compare it to something else, you might as well be standing still.
Relative to you, the other spaceship is standing still. You are both just floating there while Earth quickly moves away from you.
If you were going 90% the speed of light relative to your launching site on Earth, then if you looked back at Earth through a telescope you’d see them all aging very quickly, but to you and your neighboring spaceship, you’d both not experience any personal change. You’d be able to see the other ship and vice versa quite normally.
In fact, if you took a flashlight and pointed it straight ahead in the direction of your travel, even though you were going 90% the speed of light relative to Earth, the beam of light would leave your flashlight at the speed of light relative to you. That’s only possible because time has slowed down for you, making light always look like it’s going light speed. You will not notice any change personally.
On Earth, people looking at you in a telescope would see you were moving and aging very slowly, and although the light of your flashlight would not appear to be going much faster than your spaceship, because your time has slowed down, you see it going out at the speed of light and people on Earth are moving slowly.
Consider this. Here you stand or sit. But the earth is spinning at about 1000 mph at the equator. We are also going around the sun at about 67,000 mph and orbiting the galactic center of the Milky Way galaxy at about 514,000 mph, and our galaxy is approaching the Andromeda Galaxy at about 250,000 mph. So you are not standing or sitting still at all! You are moving very fast right now, but when you shine a flashlight in all directions the beam leaves your flashlight at the speed of light relative to you and your sense of time.
The same happens to you and your friend in the nearby spaceship. You can look out the porthole, see him, and wave and he can see you and wave back as if both your ships were stationary in space and just floating next to each other. It’s all relative.
Will Earth ever be rid of bad guys? Yes, because in the future there will be no life on Earth at all.
When all else fails, the sun will grow so hot as it ages the oceans and fresh water will dry up. Vegetation and all other lifeforms will cease to exist. Then the sun will grow and become a red giant, completely swallowing Mercury and Venus, and possibly Earth, but if not Earth, Earth would be too close for comfort from the sun’s surface.
At that point I suspect Earth will be completely void of all evil, rogue and repressive regimes and bad guys. In fact, it will be completely void of pretty much everything and look much like what Venus looks like today!