Marcelo Gleiser

Two years ago yesterday, Dec. 12, nearly 200 countries came to a consensus that greenhouse emissions — mostly caused by the burning of fossil fuels — had to be drastically cut if we were to halt the planetary-changing consequences of a choking atmosphere.

Trial and error, experimentation, the understanding that some questions have complex answers or no answers at all, the notion that failure teaches, the acceptance that mistakes can actually guide you in the right direction, persistence in the face of difficulty: These are some of the everyday components of scientific research, accumulated wisdom that can serve us well in many walks of life — from how to face challenges as individuals to running corporations.

Last week, my 13.7 co-blogger Tania Lombrozo reported on a study she developed with graduate student Sara Gottlieb on whether science can explain the human mind.

As Tania wrote, this was a survey-based study asking the participants "whether they thought it was possible for science to one day fully explain various aspects of the human mind, from depth perception and memory loss to spirituality and romantic love."

For this post-Thanksgiving week, I'd like to suggest a remarkable video produced over two decades by NASA scientists.

Satellites monitored populations of plant life on land and oceans, mapping variations of green regions of vegetation and snow cover on the North and South Poles. As seasons pass, we witness a rhythmic dance between white and green, as if the planet itself were breathing.

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.

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.

If you are going to watch The Lost City of Z expecting some sort of Indiana Jones sequel, don't bother.

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