Marcelo Gleiser

Marcelo Gleiser is a contributor to the NPR blog 13.7: Cosmos & Culture. He is the Appleton Professor of Natural Philosophy and a professor of physics and astronomy at Dartmouth College.

Gleiser is the author of the books The Prophet and the Astronomer (Norton & Company, 2003); The Dancing Universe: From Creation Myths to the Big Bang (Dartmouth, 2005); A Tear at the Edge of Creation (Free Press, 2010); and The Island of Knowledge (Basic Books, 2014). He is a frequent presence in TV documentaries and writes often for magazines, blogs and newspapers on various aspects of science and culture.

He has authored over 100 refereed articles, is a Fellow and General Councilor of the American Physical Society and a recipient of the Presidential Faculty Fellows Award from the White House and the National Science Foundation.

A little less than a year ago, I wrote on these pages about the long-standing controversy of whether running is good or bad for your heart.

On Aug. 21, a narrow, 70-mile wide swath of the United States from Oregon to South Carolina will be the stage for one of the most (if not the most) spectacular celestial events, a total eclipse of the sun.

Space.com has put together a nice informational guide, including a video and a map explaining where to go, what to expect, and how to watch it safely. This is the first total solar eclipse in America in almost 40 years. The next one in the U.S. will be on April 8, 2024.

The history of science — in particular the physical sciences, like physics and astronomy — can be told as the incremental realization that there is large-scale coherence in the universe.

By large-scale coherence, I mean that some of the same physical laws hold at scales as diverse as the atom and the galaxy, and even the universe as a whole. In a sense, the universe speaks one language and scientists act as the interpreters, translating this language in terms that humans can understand and relate to.

The largest study of its kind — analyzing data from 24,763,389 results between 1996 to 2016 — has found that the average American runner, from 5k runners to marathoners, is getting slower.

Let's face it: Vegetarians are a strict minority of the U.S. population.

The numbers seem to be increasing, though data from various surveys vary widely.

Sometimes, I veer off my beloved scientific topics to explore another of my passions — human endurance.

Today we address the composition of the universe, in the final essay of our trilogy on cosmic questions.

As the great German astronomer Johannes Kepler once wrote in the early 17th century: "When the storm rages and the shipwreck of the state threatens, we can do nothing more worthy than to sink the anchor of our peaceful studies into the ground of eternity."

This is the "big question" — the one that has been with us in one way or another since the beginning of history.

Every culture that we have a record of has asked the very same question: How did the world come to be? How did people and life come to be? Taken within this broader cultural context, it's no surprise that modern-day scientists are as fascinated with the question of origins as were the shamans of our distant ancestors.

I often get asked what an "expanding universe" really means.

It's confusing, and for very good reasons. So, if you are perplexed by this, don't feel bad. We all are, although cosmologists — physicists that work on the properties of the universe — have figured out ways to make sense of it. In what follows, I'll try to explain how to picture this.

In the next few weeks, we will address other bizarre cosmic questions, such as the meaning of the Big Bang and the future and material composition of the universe.

When it comes to particle physics — the branch of physics that tries to find nature's fundamental building blocks of matter — it's all about energy and momentum. Moving (or kinetic) energy, to be precise.

The higher the speeds of the particles, the more violent their collisions.

Why all the violence?

Well, we are trying to "see" things that are millions of times smaller than atomic nuclei. And we can't just keep cutting matter down to find its smallest pieces.

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