How long does it take to accelerate to near the speed of light while the passenger is conscious?
Humans cannot reach the speed of light, but theoretically they can get close. The acceleration limit that humans can withstand is 9 to 10 g, but when such a high acceleration is reached, it is actually difficult for humans to maintain consciousness. The acceleration that the human body is accustomed to should be the acceleration due to gravity, i.e., 98 meters per second2, if the acceleration is carried out at this speed, then the person on the spacecraft will be able to remain conscious. If the ship ends with 98 meters in 2 seconds to accelerate, from the passenger's point of view, it takes 2It will take 65 years to increase the speed to 99% of the speed of light. That is, suppose there is a spaceship that is going from Earth to the center of the Milky Way, and in the first half of the distance, the spacecraft starts with 9If you accelerate at 8 meters and 2 seconds, and decelerate the remaining half of the distance at the same distance, it will take about 20 years for the spacecraft to reach the center of the galaxy.
Of course, there are some peculiarities when the speed is close to the speed of light. That is, in the eyes of the passengers, he has only traveled at a speed close to the speed of light for a few decades, but in the eyes of people on Earth, he has been on the road for tens of thousands of years, which is the result of time dilation.