1900: A physics genius wandering around Europe

Chapter 121 Question : Twin Paradox

The first relativity seminar was truly worth the trip.

Even those who didn't understand physics could feel the excitement of the academic confrontation.

Although this is not a real fight with guns and swords, it still feels like every move draws blood.

A question is an attack from the other party, and a concept or formula is a good way to resolve the attack.

It seems silent and invisible, but in fact it is full of dangers.

It is true that the devil is always one step ahead of the righteous!
Einstein's powerful mathematical ability and rigorous logical ability gradually put pressure on those who originally opposed the theory of relativity.

People with low level of skills can't even ask good questions.

When Born's thought experiment was solved, the level of the meeting immediately rose to a higher level.

Some common problems can no longer be put on the table.

Everyone understood that it was time for the masters to fight each other.

For a moment, the atmosphere in the venue became tense, and many ordinary students' palms were sweating from the suppressed pressure.

Lorenz was also extremely excited as he had hosted so many academic conferences.

There was never a game 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 emotions of people in the venue.

That is the change from previous contempt to 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 person must be a genius no less than Bruce Lee.

"Everyone, do you have any questions?"

"I think this young man Einstein seems to be still unsatisfied and is getting more and more courageous as the battle goes on."

A low laugh broke out in the meeting hall.

Even Ridgeway smiled.

At this time, another voice sounded.

Li Qiwei felt that it looked familiar and looked back.

Hey!
It turned out to be Professor Case.

Today he was wearing a handsome suit and his hair was combed neatly. He looked energetic and a dozen years younger.

Since Chris's ranking was released, Professor Case's reputation has also risen.

Everyone in the industry knows that there is a physics professor in Cambridge. Although he is just a physicist, he has lofty ambitions and a broad mind.

He even sat down with top physicists to debate the nature of light.

Now he is striving to become a physicist. He can be said to be still strong despite his old age and still willing to move forward with his old age.

Professor Case said, "Hello, Einstein."

"My question also requires a thought experiment, but it's about time."

"Suppose there are twin sisters. The elder sister leaves the earth on a spaceship at a speed close to the speed of light, while the younger sister stays on the earth."

"After the elder sister flies for a while, she returns to Earth. Who is younger, the elder sister or the younger sister?"

"According to the clock slowing effect of the theory of relativity, since my sister is moving at a speed close to the speed of light, the time she experiences will slow down, so my sister is younger."

"But from the younger sister's perspective, motion is relative. The younger sister is moving at the same speed of light as the older sister, so the younger sister should be younger."

“So, this leads to a contradictory result.”

"How does the theory of relativity explain this problem?"

As soon as Professor Case finished asking the question, he immediately attracted everyone's attention.

He is indeed the physicist who is closest to a physicist. With such a powerful imagination, he will surely have an epiphany one day and step into the realm of a physicist!

Professor Case responded in a low-key manner. He seemed calm on the surface, but in fact he was secretly delighted.

My name, Case, has finally made its way into the physics community.

This question is very interesting, and it is a little different from Born's length contraction effect.

Because it is not a question of the sequence of events.

It seems that the theory of relativity cannot resolve this contradiction.

At this time, even those senior physicists were thinking about this problem. If they tried to deduce it from the formula, they would find it very troublesome and might not succeed.

Is this really a loophole in the theory of relativity?
Many people were breathing rapidly.

This question is obviously a level higher than the previous two, and fewer and fewer people can understand it.

"Professor Case is indeed worthy of his reputation. This question is extremely sharp. I don't think Einstein would be able to answer it."

"It's really exciting. I thought the train problem was the climax, but I didn't expect there would be another expert. Physics is really profound."

"This time, the theory of relativity is likely to lose."

Li Qiwei looked at Professor Case and it seemed that the other party had indeed undergone a transformation.

With his ability, he shouldn't be able to ask such a question.

It seems that pressure is motivation.

Professor Case, fearing that others would discover that he was a fake, suddenly had an inspiration and pointed out a fallacy.

In fact, his question is a well-known one, that is, the twin paradox.

In real history, it was proposed by Lang Zhiwan at a conference to question the contradictions of the theory of relativity.

This problem is actually a non-inertial system problem because it involves the acceleration and deceleration of the spacecraft.

If we use general relativity to explain it, it will be simpler.

However, if we use the special theory of relativity, it will be much more troublesome and the analysis process will be extremely cumbersome.

However, Li Qiwei felt very relieved when he looked at Einstein on the stage, because he knew that he would be able to answer this question.

Einstein was deeply moved at this moment!

The reason is simple, because he predicted this problem in advance, and it was Bruce Lee who raised it.

Bruce Lee asked this pointed question when the two of them were exchanging letters.

At that time, Einstein himself could not answer this question perfectly.

In the end, it was Bruce Lee who came up with a brilliant idea, gave the concept of proper time, and used the space-time diagram to solve the problem in a vivid way.

Thinking of this, he looked at Li Qiwei and gave a knowing smile.

Li Qiwei also smiled and gave a thumbs up.

Einstein took in everyone's expressions and thought to himself, I'll just give you a little shock.

He was full of confidence and said, "Thank you very much for your question, Professor Case. This is a very good question."

"If my sister keeps flying forward in her spaceship and never returns to Earth."

"Then this problem is almost a replica of the train problem just now, except that it has changed from a space problem to a time problem."

"If the spacecraft does not fly 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 watching trains shorten each other.”

"This situation can be easily analyzed from the light cone diagram."

"But the problem now is that the spacecraft has returned, and the two of them met directly in reality."

“That’s when things get complicated.”

"But fortunately, relativity can still explain this problem."

"Before I answer, let me share with you an interesting anecdote. Bruce once raised this question when I discussed it with him privately."

“And the main solution was also thought of by him.”

"Next, I will explain it to you on his behalf."

boom!
Einstein's words shocked everyone.

It turns out that this problem had already been thought of by others. No wonder Einstein was not nervous at all on the stage and had a smile on his face.

At the same time, everyone was impressed by Bruce Lee's genius.

That man was like a god, standing high in the sky, and people could only worship him.

At least the senior physicists present thought that the twin paradox could not be explained at all.

Poor Professor Case was in tears. He had thought he could make a big splash, but he didn't expect that he had always been in the hands of others.

As everyone waited, Einstein began to explain.

(End of this chapter)