Is your grandmother still alive according to Einstein’s theory of relativity? | Sciences

It was a random question. Sabine Hosseinfelder was in a taxi with a young man, and when she informed him that she was a theoretical physicist, he asked the young man: “A shaman told me that my grandmother is still alive because of quantum mechanics. Is that true?”

The young man might not know it, but Hossenfelder was the perfect person for him to ask that question.

The scientist, who now works at the Center for Mathematical Philosophy at the University of Munich in Germany, spends her time searching for answers to these kinds of questions.

“This is what sparked my interest in physics from the start: all those big questions that are hard to answer,” she told BBC News Mundo, the BBC’s Spanish-language service.

“Twenty years later, I still don’t have the answers, but if you ask me a question, I can give you a very long answer.”

These answers are reflected in journal articles and in books such as Lost In Math (“Lost In Math”, in free translation, no release in Brazil) and Existential Physics: A Scientist’s Guide to Life’s Biggest Questions (“Existential Physics: A Scientific Guide to Life’s Most Important Questions”, also without a copy in Brazil).

Moreover, she has become known through her blog BackRe (Action) and her popular YouTube channel.

Hundreds of thousands of people follow the world on the Internet. “We are drawn to mysteries,” he says.

“I think behind this attraction is a desire to understand how we fit into this universe, and what these fundamental laws that we use in physics are telling us,” explains Hossenfelder. “They don’t exactly answer all of the big questions, but they do give us an idea of ​​what is and isn’t possible.”

But let’s go back to the question at the beginning of this text: Could what the shaman said to the young man in the taxi be true?

“I didn’t really know what to answer, because quantum mechanics itself has nothing to do with the afterlife,” says Hossenfelder.

“But after thinking about it for a bit, I came to the conclusion that it wasn’t entirely fake.”

“Quantum mechanics aside, it is true that our theories of space and time, which go back mainly to Albert Einstein, tell us something about the reality of the past as well as the future, although the future is more complex because of this quantum mechanics.”

After this thread, I came up with an answer to the strange question.

“What Einstein taught us, although I think it was a surprise to him that it was even a consequence of his theory, is that basically you can’t talk about the existence of this present moment without also acknowledging the existence of the past in exactly the same way,” says Hossenfelder.

You may have already noticed: the present is a moment between the past and the future.

If you ask what you are doing now, you will answer that you are reading this article, but even this answer has a little past.

“Everything you experience, everything you see, you see as if it were a short time in the past,” Hossenfelder details.

That is, the moment “now” is impossible to describe.

Furthermore, “what we call the present moment may be someone else’s future or past. Einstein called this idea the independence of the observer.”

For a better understanding, let’s remember one of Einstein’s famous thought experiments.

Until then, two currents of physics thought differently: the Newtonians claimed that when measuring the speed of light, it would be different depending on how you were moving; Maxwell argued that the speed of light is always the same.

Einstein focused on a key component of speed: time.

And he realized that the statement about time was a question of what is simultaneous.

For example, if you say a train arrives at the station at 7:05 AM, that simply means that it arrives at the platform at the same time you read 7:05 AM.

But Einstein believed that the idea of ​​things happening at the same time actually depends on how you move.

This means that the flow of time may not be the same for everyone.

To explain this, Einstein imagined a man standing on a train station platform. Suddenly, two bolts fell on one side of it at exactly the same distance.

The light from each beam hits your eyes at exactly the same moment.

For this man, the two rays fell simultaneously.

But at that very moment a train is passing by, traveling at nearly the speed of light. There is a woman.

When light is emitted from the spokes, the train moves toward one while moving away from the other.

The light coming from the beam towards the person on the train reaches the woman’s eyes first, because the distance is shorter. The rear beam light comes on later.

That is, unlike the man on the platform, for the woman the time passed between the two rays: one fell before the other.

So if the speed of light is constant – and it is – then who is the right observer? Did the lightning strike at the same time, or one after the other?

Answer: No, and both. Both have an equally valid perspective.

“All observers have the same rights, so to speak: their reality is no more real than mine,” Hossenfelder notes.

The impossibility of defining a concept is now called simultaneous relativity.

The theoretical physicist explains: “Einstein said we have to treat time as a dimension, and he created an entity called space-time.”

“Once you do that, you can’t present a specific moment right now, because that doesn’t work for all observers.”

Following this logic, if there is no unambiguous idea of ​​what is happening now, as Hossenfelder points out, then every moment could be someone’s “now.”

This will include every moment of your past and future.

“This leads to the conclusion that the past exists in the same way as the present,” says Hossenfelder.

This thinking leads us to believe that your great-grandmother’s past exists in the same way as our present.

“Of course, if you want to talk to your grandmother, none of this will help you … We don’t know how to do it yet,” he says.

These last words caught our attention: What did you mean by “after”?

“At this point,” says the scientist, “I have to admit that the following are things that I think are interesting, but which may or may not be true.”

To say the least, we were intrigued, especially given that Sabine Hossenfelder’s musings are drawn from a study of fundamental physics.

“If you think about it, when someone dies in some way, they continue to exist,” says Hossenfelder.

“What happens is that all the information that made up your personality—the specific bonds of atoms, the synapses in your brain and so forth—disintegrates and breaks down. But we know, from the way the basic laws of nature work, that this information is not to be destroyed.”

“The only thing that happens is that it spreads out in minute associations in the remains of the body, entangles itself with other particles, and spreads across the planet and, in the long term, throughout the universe.”

So: the information is still there, but for practical purposes it is impossible to retrieve.

However, Hossenfelder wonders: who knows what will happen in a billion years?

“The universe will exist for some time, so there is potential for technological development,” Hossenfelder says.

“Even if the information that makes up a person is no longer in one place and we can’t talk to them, maybe someone will figure out how to do it. Or something in the nature of human beings can change; maybe some cosmic consciousness also spreads and this information spreads out. Make it available again. Says the scientist.

“I know it sounds crazy, and I admit I find it hard to understand intuitively, but based on what we know about how our current theories work, our existence seems to transcend the passage of time. There is something timeless about information that makes us, besides shaping all of something in the universe.”

As Einstein wrote…