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.

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.

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.

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."

Even with all the drama — and now the prolonged silence, possibly permanent — the European Space Agency's (ESA) mission to land a fridge-sized probe on a comet zipping at about 80,000 miles per hour, some 300 million miles from Earth, was a resounding success. This first ever comet landing has captivated the world as very few events in the history — certainly the recent history — of space exploration have.

Every child must leave home one day — but rarely because he has destroyed his home.

The crash of Virgin Galactic SpaceShipTwo over the Mojave Desert last Friday, killing co-pilot Michael Alsbury and seriously injuring pilot Peter Siebold, has renewed discussions on the value of commercial space exploration. Should we continue to do this at the unavoidable cost of human life? Is this simply a moneymaking enterprise so that a few people that can afford the $250,000 price tag can float for a few minutes at the edge of Earth's atmosphere?

Last week, our own Tania Lombrozo ignited an intense discussion of the differences between factual and religious belief. I want to take off from there and examine a no less controversial issue, one that has been in the limelight of cutting-edge physics for the past few years: Do some scientists hold on to a belief longer than they should? Or, more provocatively phrased, when does a scientific belief become an article of faith?

At least when it comes to physical reality, which I define here as that which exists in the cosmos, there is no such thing as complete emptiness.

Quite the opposite, it seems that the more we learn about nature, the busier space becomes. We can, of course, contemplate the idea of a metaphysical emptiness, a complete void where there is nothing, what some people like to call absolute nothingness. But these are concepts we make up, not necessarily things that exist. In fact, calling nothingness a "thing" automatically makes it into a something, a curious paradox.

The other day, I was giving a public lecture when someone asked me a question that I wish people would ask me more often: "Professor: Why are you a scientist?"

I answered that I couldn't do anything else, that I considered it a privilege to dedicate my life to teaching and research. But what's really special in this profession, to me at least, is that it allows us the space to create something new, something that will make us matter. It gives us an opportunity to engage with the "mystery," as Albert Einstein called our attraction to the unknown:

I recently started reading Superintelligence, a new book by Oxford University philosopher Nick Bostrom, who is also director of the Future of Humanity Institute. (Now, that's a really cool job title.)

A recent article in The New York Times explores the explosive wave of smartphone recordings of events, from the most meaningful to the most trivial.

Some of you may have seen "Our Story in 2 Minutes," a 2012 video edited by Joe Bush and with music from Zack Hemsey. As of this writing, it had more than 17.2 million views on YouTube from people all over the world. If you haven't seen it, here is your chance:

It was the Roman poet Lucretius, writing around 50 B.C., who famously proclaimed reason as a tool to achieve individual freedom, as a means of breaking free from superstitions that enslave the human mind:

"This dread and darkness of the mind cannot be dispelled by the sunbeams, the shining shafts of the day, but only by an understanding of the outward form and inner workings of nature."

Given that science is believed to be about certainty, betting on a scientific idea sounds like an oxymoron.

Yet scientists bet on ideas all the time, even if mostly for jest. Of course, this only makes sense before we have any data pointing toward the correctness of the disputed hypothesis.

Well into the 21st century, it is indisputable that we know more about the universe than ever before.

So that we don't get lulled into a false sense of confidence, today I provide a short list of open questions about the cosmos, focusing only on its composition. These are some of the mysteries that keep many fundamental physicists and astronomers busy and hopeful.

Mortality is humanity's blessing and its curse.

Because we are aware of the passage of time, because we know that one day we won't be here — and neither will everyone we love (and everybody else) — we have always searched for an answer to this most painful of mysteries: Why do we die?

However painful death is, to many people immortality is not any better. Why would someone immortal want to live? Where would his or her drive come from?

The origin of life remains one of the most challenging open questions in science.

We don't know (yet) how lifeless molecules self-organized to become a living entity. We do know it happened at least here on Earth some 3.5 billion years ago, possibly earlier. Perhaps "self-organized" is the wrong word, as it gives the impression that there was some kind of intention, that life is a cosmic goal and not an accident.

Last week, I came across George Johnson's piece for The New York Times, "Beyond Energy, Matter, Time and Space," where he writes, in his usually engaging style, about two recent books with opposite viewpoints concerning what we can and cannot know of the world.