What have the stars done for humanity?

Professor Roberto Trotta. Source: Imperial College London

Professor Roberto Trotta from Imperial College London’s Department of Physics is a theoretical physicist by training and an astrophysicist by trade. His work explores how statistics and machine learning can help us turn complex datasets from telescopes on Earth and in space into real-life insights.

Almost four years later, he gave his inaugural lecture at Imperial. Now, he is a Visiting Professor who wants to empower us to appreciate the sky and stars. His latest book, “Starborn,” was recently featured as BBC Radio 4’s Book of the Week.

We spoke to him to find out what the stars, the sky and everything in between bring to people, and why we should try to take care of our planet so we can still look at the stars .

When I think of space scientists, machine learning and big data are not the first thing that comes to mind. Can you explain why we use big data and AI to explore the world above us?

Machine learning and artificial intelligence are becoming essential to learning about our universe. Galileo and others once looked through telescopes and drew what they saw, and years later at the Harvard Observatory women astronomers examined hundreds of thousands of stars and galaxies with pictures. Because of the complexity and amount of data we have today, we need computers to extract scientific meaning from the deluge obtained from telescopes in space and on Earth.

One of the great cutting-edge frontiers of my field is precisely that. We explore how artificial intelligence (AI) can make sense of the universe for us. We are getting more and more data all the time, but the question is what does it all mean? And that’s where statistics and machine learning come in.

Can you explain to me what you are trying to find out, and what you hope people will learn from this work?

Different people are interested in different things. My research focuses on three main areas: what happened in the first fraction of the second of the Big Bang, how dark matter and dark energy behave, and understanding what the universe is like.

The universe is made of 25% dark matter and 70% dark energy which together make up a whopping 95% of the universe but we don’t have the slightest idea what they are.

We owe our existence to the gravitational pull of dark matter. It plays an important role in making galaxies and stars form, especially at the high speed they do. We are certain that dark matter exists, because we see that it affects the way the universe expands, and the way galaxies move. The question is what is it made of?

Dark energy is harder to explain. We see the universe growing faster and faster and we think it is caused by a repulsive force, an anti-gravity. And this is probably due to the property of empty space itself; as the universe expands it creates more space space, which in turn leads to more repulsive forces so it expands even faster. We believe that this expansion process is driven by dark energy, but no one understands what it is. And we’re trying to find out.

I don’t understand how you can investigate the first millisecond after the Big Bang, because it is such a small time frame for something that has been around for so long. How do you do it?

We now have observations from very early in the history of the universe, radiation from 380,000 years after The Big Bang. The universe has 13.8 billion years under its belt, so 380,000 years after the beginning is a fraction of its age. Thanks to these observations, we can return almost to the beginning.

We’re sure we can rebuild almost everything up to that point. But what happens there? That is the big question.

We believe that the universe expanded very, very fast at an exponential rate in a very small amount of time. We call that moment “inflation,” and we’re trying to reconstruct what that fraction of a second looked like, and what triggered it.

Although this is much higher energy than what is happening now with dark energy, it is the same expansion in effect. The two things may or may not be related.

Only 5% of the universe is made of the stuff you and I are made of. That is one of the great questions of physics. What are the remaining objects and why do they exist? Why is the universe so special?

What have you discovered so far about the universe and its strangeness?

Science has always been a collaborative enterprise, so you’re building on the shoulders of giants. I have very talented young researchers to work with

me in my group, and together we want to provide answers to these questions in a way that uses all the information available in the data with results you can trust.

It is statistical and computational and we are always looking for how we can extract this information from complex datasets.

Your book is about looking at the stars I think you have done a lot and appreciate what the stars have done for humanity.

A Yes, we are all made of stardust but the stars have done much more for us than that. The book is not about the physical nature of stars or dark matter or any of the things we have discussed so far. The book is about the cultural impact of stargazing on humanity, from the moment Homo Sapiens came out of Africa 50,000 years ago, to AI today. The stars have many answers regarding the inspiration and knowledge they give us.

You are making a comparison between Homo Sapiens 50,000 years ago to AI today. Would you say that this effect on the sky and the stars was as great as 50,000 years ago?

We have lost heaven and our connection to heaven, and you may ask if it matters? I think yes, it is very important. If we lose heaven, we lose our awareness of our deep connection back to prehitory.

We are so busy now, we live in cities, we don’t look up and we don’t pay attention to the stars, 150 years ago you could see the Milky Way from London. Now, you can barely see any stars. Wherever I am now in Trieste, Italy, where the sky is relatively dark, you can see many passing satellites, which by some estimates will outnumber the stars in 2030.

What happens when the stars disappear?

By losing connection, you lose the significance of our place in the universe and the meaning it has held for countless generations. This endangers not only the present, but our future as well.

We lose the sense that we are a blue dot floating in a vast, inhospitable dark universe, and that we are far from any place we can call home.

Our planet is irreplaceable, there is no Planet B, and we cannot colonize Mars, not on the time scale we need. We must be united because losing the stars also means losing ourselves.

Is your goal here to empower people to see?

I want to empower people to look at the stars but also think about our trajectory and mark in the universe. Even 50,000 years ago, we changed our environment to suit us. Today, there is a sense of danger through the loss of biodiversity and climate change. By looking at this very long view of the entire arc of human history and how the stars have led us, and hopefully looking up to the stars for more inspiration for the future, we should think: “Where do we go from here?” Instead of the stars or Mars, we need to reclaim the uniqueness and beauty of our place in the universe, our own planet, today.

Is it dangerous for humanity, if one day we look up to the sky and we are greeted by a great darkness, instead of stars?

It’s not dangerous, but we’ll all be poorer. Imagine a world where a veil of clouds covered the sky, as I did in Starborn, and never saw a star, the sun or the moon. It may not be dangerous, but it certainly isn’t very healing.

I see you’ve done a lot of science communication in the past. Is educating others a passion of yours?

It’s something I’ve always done, and I’ve always felt it was my duty as a scientist. I want to bring back some of that passion, excitement and enthusiasm that we scientists are lucky enough to pursue as our main line of work.

It is an honor to share that with the public.

How do you feel about your book being nominated as Book of the Week?

This is an extraordinary honor, of course, and I did not expect it. I want my book to help dispel the myth of a Planet B that we can escape from and contribute to conversations about the urgency of protecting our planet.

We need to pay attention to what is happening here and now, the next generation will have no stars and maybe no planet to live on. To me, that is the important message.

More information:
Starborn: How the Stars Made Us (and Who We Are Without Them). www.hachettebookgroup.com/titl 76/?lens=basic-books

Provided by Imperial College London

Citation: What have the stars done for mankind? (2023, December 20) retrieved 21 December 2023 from https://phys.org/news/2023-12-stars-humankind.html

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