Some people say that people on a light-speed spaceship will not age, so are human cells still active?

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This idea does not fully understand why people do not age at the speed of light. Theoretically, when a person's speed reaches the speed of light (you can imagine riding a light-speed spaceship), time stops and distance is zero. In other words, time does not pass, cells do not metabolize, and of course people do not age.

But this question says that time does not change, so why don't we get older? Which scientist said that time does not change in a light-speed spaceship? Are you just imagining it? The speed of light question is a scientific question. To understand this question, you must honestly learn some basic common sense, such as what is the speed of light, why the speed of light is the fastest speed in the universe, what is Einstein's speed of light limit and the speed of light invariance theory, why the speed of light cannot be broken, etc.

Briefly explain the theory of time dilation

In Einstein's special theory of relativity, one of the most important theories is the speed time dilation theory, which states that the faster the speed, the slower the time passes, and when it reaches the speed of light, time stops. In layman's terms, it is called the length contraction and time dilation effect, which means that the faster the speed, the slower the time passes, and the shorter the distance, and when it reaches the speed of light, time stops and the distance is zero.

That is to say, in a light-speed spaceship, you will not feel the passage of time, nor the distance. To reach any place, you will arrive in a split second. Your cells will not feel the passage of time, that is, there will be no metabolism, and you will arrive. The speed time dilation effect follows the formula: t'=t/√[1-(v/c)^2]

Here t' is the value of the speed time dilation effect; t is the time recorded by the first clock of the low-speed observer; v is the speed of the second clock relative to the first clock; c is the speed of light. According to this formula, we can understand that the time dilation effect must have a reference system, that is, there are two clocks, one is the clock in high-speed motion, and the other is the observer's clock.

The so-called time dilation or length contraction and clock slowdown is relative to the observer. That is, the clock of a stationary observer moves normally, while the clock of a person moving at high speed will slow down.

The code name of the speed of light constant is c. According to the formula, when the speed of movement reaches 0.5c, the time dilation effect reaches 1.15 times, which means that time is 15% slower relative to a stationary observer, and so on; when the speed reaches 0.8c, the time dilation effect reaches 1.66 times; when the speed reaches 0.9c, the time dilation effect reaches 2.29 times; when the speed reaches 0.99c, the time dilation effect reaches 7 times; when the speed reaches 0.9999999999999c, the time dilation effect reaches 7.07 million times.

This is no longer just a theory or conjecture, but has been verified by countless observations and experiments in the scientific community for more than 100 years and is irrefutable. This theory has been widely used in the development of science and technology and in our lives, such as satellite navigation, which would be impossible without the adjustment of the theory of relativistic time dilation.

The slowing down of the clock here should not be understood as just the slowing down of the clock scale, but rather the slowing down of the essence of time.

What is the substance or essence of time?

Time is not the scale of a clock. The scale of a clock is just a timekeeping tool set by people based on long-term experience and the natural conditions of the earth. In modern physics, that is, under the conditions of relativity, time, space, and matter are a trinity, interdependent, and cannot exist alone.

The relationship between the trinity is: space is the container of matter. Without this container, matter cannot exist and there will be no matter; matter is the content of space. Without matter, space is empty, that is, an absolute vacuum, and time and space disappear at the same time; time is the basis and record of the movement and change of matter and is one-dimensional, that is, any matter is subject to birth, aging, sickness and death, and is one-dimensional and cannot look back. When time stops, matter and space disappear at the same time.

From this we can see that time is an inherent sign of material movement and spatial changes. That is to say, when time slows down, it is not just the clock scale itself that slows down, but the substantial slowing down of the spatial changes in material movement. The clock scale only records the process of this material movement.

The essence of the human body's time slowing down is that the metabolism slows down, and time stopping means that the metabolism stops.

This sounds amazing, and it is precisely because of this amazing discovery that Einstein's greatness is even more evident. It was from the discovery of the speed of light that he created a series of theories, including the special theory of relativity and the general theory of relativity, and discovered that the essence of gravity is the curvature of space-time caused by mass.

The relativity of space and time is not only reflected in speed time dilation, but also in gravity time dilation. That is, the greater the gravity in the environment, the slower the time will be, and the time in a black hole is still.

Einstein also warned everyone: No material movement can reach the speed of light

The movement of matter cannot reach the speed of light, and of course it cannot exceed the speed of light. Einstein gave a mass-speed relationship formula through the mass-increase effect: M=m/√[1-(v/c)^2], where M is the kinetic mass of the matter, m is the rest mass of the matter, v is the speed of movement, and c is the speed of light.

According to this formula, the faster the speed of matter moves, the greater the kinetic mass (or kinetic energy). As the speed approaches the speed of light, the momentum of matter approaches infinity. What is infinity? The entire universe is finite, and if a particle moving at the speed of light becomes infinite, can the universe contain it? So this is a paradox.

No particle can reach the speed of light, which has been confirmed by countless experiments and observations by scientists. In the Large Hadron Collider, scientists use huge energy to accelerate a beam of protons to 99.9998% of the speed of light, and its energy level reaches 7 trillion electron volts, which is equivalent to an aircraft carrier sailing at a speed of 20 knots. Its kinetic energy is already amazing.

At this point, if we add a 9 or 1 to the end of this percentage, the energy required will increase exponentially, and finally it will be impossible to concentrate the world's energy to push a particle to speed up. This proves that no matter can reach the speed of light, even a trillion particles can stand on the tip of a needle, let alone a spaceship or a person?

Therefore, the human delusion of extending life by using light-speed spacecraft will never come true. In the so-called high speed, such as 1% of the speed of light, that is, 3,000 kilometers per second, future spacecraft may be able to reach this speed.

However, the time dilation effect of this speed is extremely small. According to the formula, the time dilation effect is about 1.00005, which means that time will slow down by 0.05%. In this way, life span will be extended by 1577.88 seconds in one year, which is about 0.44 hours. In 100 years, life span will be extended by 44 hours, which is less than 2 days.

However, in high-speed spacecraft, the damage to the body caused by radiation, weightlessness, etc. will far outweigh the longevity effect brought by speed. For example, although the space station is well protected, astronauts will suffer great damage to their bodies after only staying there for half a year or a year, such as osteoporosis and radiation damage. It will take a long time to recover after returning to Earth.

Therefore, don’t dream about the longevity of a light-speed spacecraft, what do you think? Welcome to discuss, thank you for reading.

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