For a hundred years, we've sensed the presence of an invisible force. Dark matter. First proposed by Fritz zwicky in the 1930s and later confirmed beyond a reasonable doubt by Vera Rubin herself. What would the universe look like without dark matter? Galaxies would still form, but they fly apart. Their outer stars would spin off like sparks from a pinwheel. In 1933, Fritz Zwicky noticed this problem in galaxies within the Coma Cluster. The visible matter couldn't account for the galaxy speeds he observed. He called it dunkle natire dark matter.

Decades later, Vera Rubin found the same mystery in spiral galaxies. Stars far from the center weren't slowing down. Rotation curves were flat, speeding up an astronomical anomaly, begging for an invisible explanation. Imagine two galaxies, one governed by Newton's laws alone and one with an unseen halo of dark matter. In the dark matter rich galaxy, stars at the outer edges orbit almost as swiftly as those near the center. This observation is a cornerstone of the dark matter hypothesis. It suggests not only that there's an unseen mass enveloping the galaxy, but but that the dark matter would produce a telltale heartbeat, revealing its presence. This iron ball is heating to 3,000 degrees.

As it glows, it's radiating light across the electromagnetic spectrum. We can see it, we can measure it, we can interact with it. This is normal matter behaving exactly as we expect. It's dark and it's matter, but it's not dark matter. And most of the universe, it's nothing like this ball. Picture this. You're hunting for something that makes up 85% of the universe. But you've never seen it, can't touch it.

And you aren't even sure you can prove that it exists. Your detector sits a mile underground, colder than Antarctica, waiting for a collision that might happen once in a decade. And when it finally does, you're not even sure it's real. That's exactly what happened to my guest today. And what he discovered next will completely change how you think about the invisible universe around us.

I knew this Dharma results since I was an undergrad student in 1995. From experimental point of view, other experiments, almost all of these experiments that are more sensitive than Dharma have already excluded that particular signal.

Imagine Earth plowing through a cosmic headwind of invisible particles, dark matter particles. As our planet circles the sun, we glide on a helix, riding through that dark matter wind. Sometimes we push against it. Sometimes it blows with us. In March, the Earth trails behind the Sun. By June, it charges straight into the stream. The signal peaks. Six months later, the Earth swings around, moves away and the wind slackens.

It's then when the signal dips and then the pattern repeats. Orbit after orbit, year after year. This annual rise and fall is the telltale heartbeat of scientists have been searching for the faint whisper of dark matter. And this signal is what the Dama Libra experiment claims to have seen not just for one or two years, but for nearly the past 30 years. The signal that piqued Kaichuan's interest 30 years ago was produced by the Dama Libra experiment. It shows the telltale pulse of our cosmic dance around the sun as the sun itself moves around our galaxy. The predictions of the dark matter model match exactly on what Dharma Libra has observed. So why don't all of Kaixuan's colleagues agree that Dharma has made the definitive detection?

Right here on the campus of UC San Diego, scientists are working to see the invisibil the missing matter that makes up most of the matter in the universe. What they do is very complementary to what scientists using cosmic microwave background do. We're all on the same team. Although it's claimed that scientists competitors have seen a dark matter Signal for over 30 years, this signal remains controversial. We'll explore the nature of that signal, how it was made, how it was first detected and why colleagues are very skeptical about it. We'll interview the primary players in the new generation of searches. Using liquid noble gases like xenoc, fighting against backgrounds man made natural and cosmic in nature. We'll reveal the techniques and technologies that spin off from this research in a.

Fascinating way that this research into cosmology.