Chapter 121 Question 2: The Twin Paradox
The first symposium on the theory of relativity was indeed a worthwhile trip.
Even those present who do not understand physics can feel the excitement of academic confrontation.
Although this is not a fight with real swords and guns, it is still like inviting blood.
A question is the opponent's attack, and a concept or formula is a trick to resolve the attack.
It seems silent and invisible, but in fact it is surrounded by dangers.
It’s true that the Tao is as high as the devil!
With Einstein's powerful mathematical ability and rigorous logical ability, people who originally opposed the theory of relativity gradually gained pressure.
People with low skills cannot even ask questions well.
When Born's thought experiment was solved, the level of the meeting immediately increased.
Some ordinary problems can no longer be put on the table.
Everyone understands that it will be time for the masters to compete with each other later.
For a time, the atmosphere in the venue became tense, and many ordinary students had sweaty palms due to suppression.
Lorenz was also extremely excited. He had chaired so many academic conferences.
There has never been a scene that made him feel tense.
But now, he felt it!
As the host, he has the most comprehensive perspective and can clearly distinguish the changes in the emotions of everyone in the venue.
That is from the previous contempt to the current caution. The theory of relativity is not easy to falsify!
Even he himself was impressed by Einstein's analysis and ideas.
He felt that the other party must be a genius no less than Bruce Lee.
"Everyone, do you have any questions?"
"I see that this young man Einstein seems to have more to say, and the more he fights, the braver he becomes."
There was a burst of laughter in the venue.
Even Li Qiwei smiled.
At this time, another voice sounded.
Li Qiwei felt something familiar and looked back.
Oops!
It turned out to be Professor Case.
Today he is wearing a handsome suit and his hair is meticulously combed. He looks energetic and ten years younger.
Since Chris’s ranking was released, Professor Case’s reputation has also grown.
Everyone in the industry knows that there is a physics professor in Cambridge. Although he is only a mere physicist, he has lofty ambitions and a broad mind.
I even sat down with top physicists to debate the nature of light.
Now he is sprinting towards the realm of physicist. He can be said to be strong and strong, and would rather move away from his old age.
Professor Case said: "Hello, Einstein."
"My question also requires a thought experiment, but it is about time."
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"Suppose there are a pair of twin sisters. The elder sister leaves the earth in a spaceship with a speed close to the speed of light, while the younger sister stays on the earth." What about being young? "
"According to the clock slowness effect of the theory of relativity, because the sister is moving at a speed close to the speed of light, the time she experiences will slow down, so the sister is younger."
"But in the eyes of the sister. Come on, movement is relative. The younger sister is moving at the same speed as the older sister, so the younger sister should be younger. "
"So, this will lead to a contradictory result. "
"How does the theory of relativity explain this problem?"
When Professor Keyes finished asking, he immediately received everyone's attention.
As expected, he is indeed a physicist who is closest to a physicist. With this powerful imagination, he will surely have an epiphany and step into the realm of a physicist in the future!
Professor Case responded in a low-key manner, calm on the surface, but actually secretly happy inside.
My name, Keyes, finally appears in the world of physics.
This question is very interesting. It is a bit different from Born's shrinkage effect just now.
Because it is not a matter of the order of events.
The theory of relativity does not seem to be able to resolve this contradiction.
At this time, even the senior physicists were thinking about this issue. If they derive it from the formula, they will find it very troublesome and may not be successful.
Is this really a flaw in the theory of relativity?
Many people have shortness of breath.
This question is obviously a higher level than the previous two, and fewer and fewer people can understand it.
"Professor Case is well-deserved. This question is so sharp that I guess Einstein couldn't answer it."
"It's really exciting. I thought the previous train question was the climax, but no. Thinking that there are masters, physics is really profound.”
"This time, the theory of relativity is probably going to fail."
Li Qiwei looked at Professor Case, and it seemed that the other party had indeed undergone a transformation.
Originally, with his strength, he should not be able to ask such a question.
It seems that pressure is motivation.
When Professor Case was afraid that others would find out that he was a parallel import, he was inspired to point out a fallacy.
In fact, his problem is a famous problem, that is, the twin paradox problem.
In real history, it was proposed by Langevin at a meeting to question the contradictions of the theory of relativity.
Because this problem involves the acceleration and deceleration of the spacecraft, it is actually a non-inertial system problem.
If we use general relativity to explain it, it will be simpler.
But if you use special relativity, it will be a lot of trouble, and the analysis process is extremely cumbersome.
However, Li Qiwei looked at Einstein on the stage and felt very relieved because he knew that the other person would definitely be able to answer this question.
Einstein was feeling extremely emotional at this moment!
There is no other reason, because he predicted this problem in advance, and it was also raised by Bruce Lee.
Bruce Lee asked this pointed question when the two of them exchanged letters.
Einstein himself at the time could not answer this question perfectly.
In the end, Bruce Lee came up with a fantastic idea that gave the concept of proper time, and combined it with the space-time diagram to solve this problem vividly.
Thinking of this, he looked at Li Qiwei with a knowing smile.
Li Qiwei also smiled softly and gave a thumbs up.
Einstein Xin has a panoramic view of everyone’s expressions, and I will give you a little shock.
He was full of confidence and looked down upon the world, saying: "Thank you very much for your question, Professor Case. This is a very good question."
"What if my sister drives the spaceship and keeps flying forward and never returns to the earth."
"Then this problem is almost a replica of the train problem just now, except that it changes from a space problem to a time problem. "
"If the spacecraft never flies back, then according to the theory of relativity, if the two of them can see each other, they are indeed younger than each other."
"It's like seeing the trains become shorter than each other. Same.”
“This situation can be easily analyzed from the light cone diagram.”
"But the problem now is that the spacecraft has returned and the two people met directly in reality."
"This situation will become complicated."
"But luckily Yes, the theory of relativity can still explain this problem."
"Before answering, I will share with you an anecdote, that is, this problem was raised by Bruce when I discussed it in private."
“And the main solution was also what he thought of.”
"Next, let me explain it to everyone on his behalf."
Boom!
Einstein’s words shocked everyone.
It turns out that this problem has been thought of by others for a long time. No wonder Einstein was not nervous on stage and had a smile on his face.
At the same time, everyone was impressed by Bruce Lee's genius.
That man is like a god, standing high in the sky, and people can only worship him.
At least the senior physicists present believe that the twin paradox cannot be explained at all.
Poor Professor Keyes was on the verge of tears. He originally thought he would become a sensation, but he never expected that he would always be in the hands of others.
With everyone’s expectations, Einstein began to explain.
(End of this chapter)