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.

Since my last post was on Earth's hosting of life, it's natural to follow with a discussion of life elsewhere.

From the outset, we must state two essential facts: first, that we have no concrete evidence that intelligent aliens have ever visited our planet; and, second, that we have no evidence that there is life outside Earth, intelligent or not.

Let's look into the alien visitation question first — and leave the question of life elsewhere for another time.

Living in cities or suburbs, amid the race of everyday routine, we have little time to care about what goes on at the planetary level — or about the uniqueness of our planet.

As Europe was being torn apart in the early 17th century by conflicts between Catholics and Protestants — that would lead to the devastating Thirty Years War in 1618 — the German astronomer Johannes Kepler wrote:

"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."

Some 130 million years ago, when dinosaurs roamed Earth, two dead stars in a far-away galaxy collided violently, after spiraling around each other for millions of years.

The dead stars were neutron stars, exotic objects the size of Mount Everest and with the mass of the sun. Being this small and dense, the gravitational force is fierce. Someone once compared the pull of gravity near the surface of a neutron star to having all the population of Paris tied to your feet.

As a Brazilian-born scientist, it pains me to witness the devastating cuts — and proposal of future additional reductions — to the country's science funding.

The cut of 44 percent in March brought the 2017 budget for Brazil's Ministry of Science, Technology, Innovation and Communications the lowest level in 12 years. Additional cuts of about 16 percent have been proposed for the 2018 budget.

In 1915, Albert Einstein concluded his General Theory of Relativity, a theory that would revise our understanding of gravity in radical ways.

Before Einstein, the dominant description of gravitational phenomena was based on Isaac Newton's theory, proposed in 1687. According to Newton, every two objects with mass attract one another with a force proportional to their masses and inversely proportional to the square of their distance: double the distance, the attraction falls by a factor of four.

Albert Einstein didn't like them.

To him, black holes were a bit of an embarrassment, as they compromised his dream of a "rational" nature, that is, natural phenomena that we could describe and quantify with the usual methods of science. According to this view, good scientific theories shouldn't generate absurd (read: "irrational") results.

If it's true that a picture is worth a thousand words, what NASA's Cassini mission has left for us is indeed a treasure.

Launched in 1997, the mission terminated dramatically last week with the probe's final plunge into Saturn's upper atmosphere.

The Sign, a documentary directed, shot and produced by Josh Turnbow and Robert Dvoran and set to air Thursday, addresses whether the end of days is coming this month, as some biblical literalists predict.

The "sign" in the title refers to an alignment in the sky peaking on Sept. 23, whereby Mercury, Venus, Mars, and Jupiter will be around the constellations of Virgo and Leo, together with the sun and moon. Sept. 23 is when Jupiter leaves Virgo after being there for a while.

America seems to be a magnet for devastating hurricanes these days.

This year, Harvey came out strong with its horrific toll on parts of Texas and Louisiana. Now Irma, downgraded slightly Friday morning to a Category 4 storm from its most recent days as a Category 5, has left destruction in its wake as it plows through the Caribbean and Cuba — and is on path to hit Florida Sunday morning.

Hurricane Harvey is a devastating reminder of how helpless we are when facing nature's human-dwarfing powers.

We dig holes and barricades, build dams and create ingenious systems of canals and levees. We try to pull the brakes on natural forces, or at least tame them. These measures protect us, and we surely would be worse off without them. We have come a long way since our cave dwellings.

This has been quite a space week for Americans.

After Monday's stunning solar eclipse, Wednesday night PBS will air its two-hour documentary film about the two Voyager missions, launched 40 years ago. The Farthest: Voyager In Space, celebrates a technological and intellectual achievement rarely matched in history. Two small, nuclear-powered spacecraft have traveled farther than any other man-made machine and have forever changed our views of the solar system — and our place in it.

"Nature loves to hide."

This is how, more than 25 centuries back, the pre-Socratic Greek philosopher Heraclitus of Ephesus expressed the sense of mystery we all feel when we start pondering how the world works.

There seem to be hidden mechanisms, secret pacts between the things that make the world the world, from the smallest building blocks of matter to the neurons in our brains to the way the whole universe is stretching out in its inexorable expansion.

I entered the packed cafeteria with tray in hand, searching for the right food to eat.

Around me, hundreds of people of all ages spoke excitedly in dozens of different languages, commenting on each other's ideas, asking questions, and thinking of the next steps in their research programs.

Lunchtime at the United Nations?

There is comfort in distance, especially when the distance is in time.

Things that will happen far in the future seem not to bother us much, given that we will, most likely, be out of the picture.

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.

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

The idea that neuroscience is rediscovering the soul is, to most scientists and philosophers, nothing short of outrageous. Of course it is not.

Picture this: You are in the bathroom, doing your usual thing after breakfast, when you notice blood in the water sitting in your white, porcelain toilet.

Scared, you schedule an appointment with a gastroenterologist, who recommends a colonoscopy and a biopsy. It could be cancer, it could be a harmless colitis. But there you are, confronted, perhaps for the first time of your life, with your own mortality.

In the current issue of the New York Review of Books, David Kaiser and Lee Wasserman, the president and the director of the Rockefeller Family Fund (RFF), respectively, explain why the organization decided to divest its holdings on fossil fuel companies.

Although the divesting decision is broad-ranging, they single out ExxonMobil for its "morally reprehensible conduct."

I start with a remarkable quote:

There's no question that running changes your heart.

The issue is whether these changes are good or bad. I don't mean the occasional 3 miles once or twice a week, although even this minimal amount of exercise seems to have positive health benefits.

On Aug. 15, the news broke that a Russian radio telescope detected strong signals from outer space.