What is dark matter, the unseen stuff that makes up most of our universe? No one knows – yet.
The new XENON1T experiment at Italy’s Gran Sasso Laboratory is led by an international team of scientists who will be able to search for dark matter with unprecedented sensitivity. XENON is so sensitive that it will be able to detect the flash of light from a single photon. Dr. Ran Budnik heads the Weizmann Institute’s pivotal XENON1T team, which is responsible for the control system, the active water shield around the detector, and the external calibration system. This Nature article has more information.
The subject of dark matter has gotten some close attention lately, including from one of my favorite people, Lisa Randall, a professor of theoretical physics at Harvard University. Maria Popova, creator of Brain Pickings, recently wrote a review of Randall’s book, Dark Matter and the Dinosaurs for The New York Times. When Maria posted a picture of the book (on her Instagram feed, brainpicker) after she’d read it in preparation for writing the review, it was so full of neon sticky notes that they looked as if they might outnumber the pages. This level of scrutiny and dedication won’t surprise anyone who knows Popova.
In her review, Popova describes Randall’s theory that a “thin disk of dark matter in the plane of the Milky Way triggered a minor perturbation in deep space that caused the major earthly catastrophe that decimated the dinosaurs.”
Hang on. I thought dark matter just kind of sat there, taking up 85 percent of the universe, interacting with gravity but not with light. Why would it suddenly kill the dinosaurs, and...hang on again....what does that mean for the species, including us, roaming the same tiny blue planet in space today?
“Sixty-six million years ago,” Popova wrote, “according to [Randall’s] dark-matter disk model, a tiny twitch caused by an invisible force in the far reaches of the cosmos hurled a comet three times the width of Manhattan toward Earth at least 700 times the speed of a car on a freeway. The collision produced the most powerful earthquake of all time and released energy a billion times that of an atomic bomb, heating the atmosphere into an incandescent furnace that killed three-quarters of Earthlings. No creature heavier than 55 pounds, or about the size of a Dalmatian, survived. The death of the dinosaurs made possible the subsequent rise of mammalian dominance, without which you and I would not have evolved to ponder the perplexities of the cosmos.”
That last part really got me. It’s strange how the cosmos works, and how it seems to point in the direction of protecting emerging intelligence. Early in the life of our solar system, for example, our planet was bombarded with cosmic debris. Now, we are protected by the gravity of Jupiter, which makes it less likely that the Earth will be dealt a fatal blow. Maybe this has nothing whatsoever to do with Randall’s theory that dark matter wiped out the dinosaurs, paving the way for more intelligent creatures to emerge, but I couldn’t help but think about it when I read about her theory.
Unlike most scientists who believe that dark matter is likely made up of only one type of particle, Randall theorizes that it may be comprised of “a variety of building blocks that interact through different forces.” This theory considers the possibility that “while most dark matter doesn’t interact with ordinary matter, a portion of it might."
I’ve read all of Randall’s books, and I'm planning to curl up with her latest over the holiday break. She an imaginative, funny, brilliant, and clear writer, and her thoughts on creativity in the scientific process have changed the way I do my own work and think about the world. I’ve always seen creativity everywhere, even in the most tedious circumstances, but it was from Randall that I realized what it truly means to live in this universe at the human scale, which happens to be right smack in the middle between the macro and nano scales that we are now able to perceive, thanks to science.