More information about the lecture competition with Kim Thorne and Thomas Hertog about the Einstein Telescope (followed by the documentary) Far, near) It can be found at the bottom of this article.
In 1916, Albert Einstein gave new meaning to concepts such as gravity, space, and time with his theory of relativity. It will take less than a hundred years before the gravitational waves he predicted are first measured. Theoretical physicist Kip Thorne won the Nobel Prize in Physics along with Rainer Weiss and Barry Parish.
Their discovery did not come out of nowhere. In 1969, Joseph Weber appeared in the world press. His measuring device, a bar detector, finds evidence of gravitational radiation. Scientists here and there in the world repeat its tools, but no one can confirm its results. Meanwhile, different research groups are working on a detector based on a completely different principle: interferometry.
How did you experience that period as a young researcher?
“I still vividly remember participating in the Summer School of Theoretical Physics in Les Houches, France in 1963. Weber inspired me with his discussions of gravitational waves. His method turned out to be not the right choice, but without him the search for gravitational waves would not have advanced so quickly. It was only in the 2000s that higher sensitivity was achieved using interferometry compared to a bar detector.
LIGO's first measurement campaign, from 2002 to 2010, yielded nothing at all. Doesn't this shake confidence in detecting gravitational waves?
We knew that in principle we would not measure anything during that period. The first detectors were not sensitive enough to detect weak signals of gravitational waves. It was clear from the beginning that it would only work with the second generation.
Then the time finally came: On September 14, 2015, LIGO measured a gravitational wave for the first time. However, its official announcement did not come until months later. What was behind it?
“When I saw the signal coming, it seemed too good to be true. We thought one of the employees wanted to test us. Every now and then a false signal is deliberately inserted into the data to test the vigilance of the data analysts. Only after about two months did we become convinced that it was a real signal.”
The search might also have ended in nothing. Have you ever regretted not choosing a “safer” research field?
'never! As Ray Weiss once said: “The whole process was a lot of fun.” In retrospect, it turned out to be a huge success. But even if we fail, I will never regret it. There were a lot of aspects of physics involved. This made it particularly interesting.
I entered experimental research as a theoretical physicist. How did you manage to bridge the gap between the two worlds?
“For decades, the theory of relativity had been the domain of mathematicians, with almost no connection to experimentation. But as a graduate student at Princeton, I felt that this was changing. That's why I also delved into the experimental sciences, including gravity. I also conducted experiments in physics Particles using a cyclotron in the Physics Building at Princeton University. It turns out that I am well placed as a link between theory and experiment.
There are many phenomena that can cause gravitational waves. You were already convinced in the 1980s that black hole mergers offered us the best detection probability. How did you get there?
“In the early 1970s, supernovas were at the pole. Later, merging stars, such as neutron stars, appeared. At that time, we weren't even sure that black holes existed, let alone that they could merge. But colliding black holes have a greater mass So many neutron stars, so you could measure them 10 times as many in the universe. My assessment – later correctly – was that this would overcompensate for the smaller number of them.
If you have the rare pleasure of winning a Nobel Prize, it usually takes decades. In your case it went very quickly. What does this say about the importance of the discovery?
“It's even stronger, because in the presentation they apologized for not giving the award a year ago!” But it appears that at the time of our correspondence we had already passed the nomination deadline. When I got the call from Sweden, I was somewhat disappointed that the award did not go to the entire team. We made up for this somewhat by having as many team members as possible come to Stockholm for the ceremony. “I think there were 75 of us.”
“But actually, the fact that recognition came so quickly shows how important the detection of gravitational waves is to science. Ultimately, as far as we know, you only have two types of waves that give you information about what's going on far out in the universe: electromagnetic waves, which we measure with telescopes Like the ones we've developed since Galileo, gravitational waves.'
There are several initiatives underway regarding gravitational wave detection: the Einstein Telescope here with us, the US-based Cosmic Explorer, LIGO-India, and even the space-based gravitational wave detector, LISA. How do you view these developments?
'Really beautiful! Our understanding of the universe will be profoundly changed by what we have come to call multi-messenger astronomy. You can measure phenomena using different instruments, such as telescopes, gravitational wave detectors, and neutrino detectors.
Do you expect that we will eventually be able to measure gravitational waves generated by the Big Bang itself?
“We should be able to do this indirectly in the next 10 years by looking at the polarization of the cosmic background radiation. For direct measurements, I expect a lot of gravitational wave detectors in space. This may be a bit too early for the first of these planets, LISA.” But its successor, the Big Bang Observer, should be able to give us the answer around 2050-2060. Once we correctly map the universe's expansion history, we may discover the nature of dark energy.
I have sometimes compared the successive theories of Newton and Einstein, and perhaps future quantum gravity, to matryoshka dolls, wooden dolls that fit together. Do you think there is an inner doll, in which we will find a theory for everything?
'I don't know. I expect that we will be able to find out whether there is a deeper layer or not – that will be something for my granddaughter's generation, who is also a physicist by the way.
She and artist Leah Halloran recently published The Warped Side of the Universe, a book full of drawings, thoughts, and poems about profound questions. How do you see the relationship between art and science?
“The laws of nature are written in the language of mathematics. They are very reliable, but at the same time cumbersome and slow. That's why you have to develop a kind of intuition that tells you what calculations are worth doing, and what you will approximately end up with. For me it is done using pictures.”
“Just like my dear friend, the late Stephen Hawking, I think in geometric structures and images. For me, this makes art and science closely related. In addition, imagination also plays an important role in science communication.”
The future belongs to the youth
Do you encourage young people to use their talents to research gravitational waves?
It's harvest time in gravitational wave physics. It will only increase in the coming decades. But at the same time I would like to emphasize that in this specialty you basically… Great sciencesituation, with extensive partnerships. I must admit that this does not suit me. The younger version of me might not end up in gravitational wave research today.
“Hence my main advice: Take your personality into consideration when making your choice. Also: To be successful, you have to work hard. So choose something that gives you a lot of happiness, so you can put in all that hard work.”
The new underground Einstein Telescope will be Europe's most advanced gravitational wave observatory. Why do we need such a telescope? Why is the detection of gravitational waves so essential to physics? Which country will get it? The Netherlands, Belgium and Germany are jointly investigating whether they can accommodate such a global observatory. on Saturday, March 23 at 7 p.m Kip Thorne and Thomas Hertog will talk about it during the Dukeville conference in Leuven.
This lecture follows immediately World premiere of Far, near. Would you like to be there? EOS allowed 5 double cards to leave of! Send us an email And mention that you want a chance to win tickets. We will draw five bilateral tickets between the participants.
You can find more information about this event here.
