Self-Motivation
David Goggins
Former Navy Seal
Career Development
Bryan Cranston
Actor
Critical Thinking
Liv Boeree
International Poker Champion
Emotional Intelligence
Amaryllis Fox
Former CIA Clandestine Operative
Management
Chris Hadfield
Retired Canadian Astronaut & Author
Learn
from the world's big
thinkers
Start Learning

Without Dark Matter, It's Unlikely That Any of Us Would Exist at All

Never have so many owed so much to — something so invisible.

Lisa Randall: Dark matter is just a form of matter, which is to say it acts like matter when it comes to gravity. So it clumps together like the matter we know about. It’s found in galaxies, for example, because of gravitational force. What distinguishes dark matter from ordinary matter is that it has no interaction as far as we know with light. So we see ordinary matter. It’s made up of atoms. Atoms are made up of charged particles. But so far as we know, dark matter is just an entirely new form of matter not made up of atoms, not made up of the stuff we’re familiar with. And the question we eventually have is what is it made up of exactly?

But as far as the physics of the universe goes, it’s just a form of matter. The reason we’re aware of dark matter is because of the gravitational effects. In fact, if you look at just the energy stored there’s five times as much dark matter as there is ordinary matter. So you observe this gravitational effects in galaxies for example. I mean one of the ways we first knew about dark matter was by looking at the motion of stars. The motion of stars responds to the gravitational force of all the matter around. It doesn’t care whether or not it interacts with light. The stars of course are bright because they interact with light. But they’re responding to the gravity of the matter including the dark matter. So that was evidence for dark matter. And now there’s lots of other evidence for dark matter too having to do with the way light bends or what galaxy clusters look like when they merge. So there’s really a lot of physical evidence that tells us dark matter is out there in the universe. Then the question for theoretical physicists like myself becomes: What is this stuff and what do we mean by that? Well, is it an elementary particle? Is it more than one elementary particle? If it is a particle, what is the mass of that particle? Does it have any interactions at all?

So far we haven’t seen any interactions with the light with which we’re familiar, but maybe there’s a small interaction that we just haven’t seen yet or maybe it attracts in an entirely different way. The only thing we know for sure is that there is this matter and it interacts via gravity. Dark matter was actually essential to the formation of structures we see in the lifetime of the universe. Now it’s important to say structures we see in the lifetime of the universe. Even without dark matter, structure would have formed. But the actual size of the galaxies that we see is only possible because dark matter was present. Ordinary matter interacts with radiation. Radiation would have washed away small objects like galaxies. Now I realize galaxies don’t seem small to you, but on the scale of what radiation could wash away they’re actually small. So dark matter was essential to forming objects of that size. It also was important because it meant that matter came to dominate over radiation sooner in the evolution of the universe because there was a lot more matter. And again matter domination is important for the formation of structure because radiation won’t form structure. I mean just think about it. Light’s not clumping into little balls the same way matter would. So both because of its abundance and because it doesn’t interact with light, dark matter was actually essential to the formation of the structure that we see.

Here's what we know about dark matter:


1. It's there.

2. Its gravity affects things around it.

3. Aside from those two, we don't really know much.

That doesn't mean there aren't plenty of people who would like to help out...

Physicist Lisa Randall steps up to the Big Think camera this week to share her thoughts on dark matter and space in general. She's just recently published a book about dark matter, called Dark Matter and the Dinosaurs: The Astounding Interconnectedness of the Universe.

The “new normal” paradox: What COVID-19 has revealed about higher education

Higher education faces challenges that are unlike any other industry. What path will ASU, and universities like ASU, take in a post-COVID world?

Photo: Luis Robayo/AFP via Getty Images
Sponsored by Charles Koch Foundation
  • Everywhere you turn, the idea that coronavirus has brought on a "new normal" is present and true. But for higher education, COVID-19 exposes a long list of pernicious old problems more than it presents new problems.
  • It was widely known, yet ignored, that digital instruction must be embraced. When combined with traditional, in-person teaching, it can enhance student learning outcomes at scale.
  • COVID-19 has forced institutions to understand that far too many higher education outcomes are determined by a student's family income, and in the context of COVID-19 this means that lower-income students, first-generation students and students of color will be disproportionately afflicted.
Keep reading Show less

How Hemingway felt about fatherhood

Parenting could be a distraction from what mattered most to him: his writing.

Ernest Hemingway Holding His Son 1927 (Wikimedia Commons)
Culture & Religion

Ernest Hemingway was affectionately called “Papa," but what kind of dad was he?

Keep reading Show less

The biology of aliens: How much do we know?

Hollywood has created an idea of aliens that doesn't match the science.

Videos
  • Ask someone what they think aliens look like and you'll probably get a description heavily informed by films and pop culture. The existence of life beyond our planet has yet to be confirmed, but there are clues as to the biology of extraterrestrials in science.
  • "Don't give them claws," says biologist E.O. Wilson. "Claws are for carnivores and you've got to be an omnivore to be an E.T. There just isn't enough energy available in the next trophic level down to maintain big populations and stable populations that can evolve civilization."
  • In this compilation, Wilson, theoretical physicist Michio Kaku, Bill Nye, and evolutionary biologist Jonathan B. Losos explain why aliens don't look like us and why Hollywood depictions are mostly inaccurate.
Keep reading Show less

Masturbation boosts your immune system, helping you fight off infection and illness

Can an orgasm a day really keep the doctor away?

Image by Yurchanka Siarhei on Shutterstock
Sex & Relationships
  • Achieving orgasm through masturbation provides a rush of feel-good hormones (such as dopamine, serotonin and oxytocin) and can re-balance our levels of cortisol (a stress-inducing hormone). This helps our immune system function at a higher level.
  • The surge in "feel-good" hormones also promotes a more relaxed and calm state of being, making it easier to achieve restful sleep, which is a critical part in maintaining a high-functioning immune system.
  • Just as bad habits can slow your immune system, positive habits (such as a healthy sleep schedule and active sex life) can help boost your immune system which can prevent you from becoming sick.
Keep reading Show less

Live on Tuesday | Personal finance in the COVID-19 era

Sallie Krawcheck and Bob Kulhan will be talking money, jobs, and how the pandemic will disproportionally affect women's finances.

Quantcast