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Carl Sagan on 'Cosmos'

Over the past few years, there has been a growing number of people who believe the Earth is flat. A 2019 YouGov survey of more than 8,000 Americans found that as many as one in six are "not entirely certain the world is round."

Flat Earth Theory has, surprisingly, gained a lot of traction. A 2021 study published in the National Library of Medicine posited that the theory is buoyed by "the cognitive tendency to interpret, favor, and recall information in order to strengthen one's personal beliefs" or, in other words, confirmation bias. Though the "how" and "why" of Flat Earth Theory and its popularity is fascinating (and troubling, to be honest), the scientifically proven truth is that the Earth is round. It is a globe. It is spherical.

Of course, the knowledge that the Earth is round is not new. Ancient Greek philosophers across centuries studied and found evidence that the Earth is indeed round thousands of years ago. Way back in the 6th century BC, Pythagoras first proposed the Earth was round from observing the shape of the Moon. In the 5th century, Empedocles and Anaxagoras noticed evidence of the Earth's true shape by observing its curved shadow during lunar eclipses. In the 4th century, Aristotle argued the Earth was round after noting how ships disappear "hull-first" over the horizon line. In the 3rd century, Eratosthenes actually calculated the Earth's circumference using geometry and shadows with shocking accuracy.

earth, globe, sphere, flat earth, skeptics, scienceWe've got the whole (round) world in our hands. Image via Canva

Naysayers remain skeptical, and there's probably no changing their minds, but to this day, experts insist the Earth is round and back it up with cold, hard science. NASA posted this video just days ago. Watch:

- YouTubewww.youtube.com


Here's where Carl Sagan comes in.

Sagan hosted the original version of TV's Cosmos: A Personal Journey in 1980-81. According to PBS, Cosmos would become "one of the highest-rated programs in the history of public television" largely due to Sagan's ability for "reinterpreting intricate scientific jargon into elegant and memorable statements that the common person can easily conceptualize and appreciate." The show would be revived in 2014 with astrophysicist Neil deGrasse Tyson at the helm.

In the first episode of Cosmos, Sagan easily proved the Earth was a sphere using a piece of cardboard, some sticks, and the work of none other than the ancient Libyan-Greek scholar, Eratosthenes. Watch:

- YouTubewww.youtube.com

"How could it be, that at the same moment, a stick in Syene would cast no shadow and a stick in Alexandria, 800 km to the north, would cast a very definite shadow?" Sagan asked. "The only answer was that the surface of the Earth is curved," he concluded. "Not only that, but the greater the curvature, the bigger the difference in the length of the shadows."

Considering the distance between the two cities and the lengths of the shadows they produced, Eratosthenes was able to determine that the Earth had a seven-degree curve. He used that calculation to speculate the Earth was 25,000 miles in circumference.

These days, we know that the earth is 24,901 miles in circumference, which means Eratosthenes was less than 100 miles off. Didn't we say his accuracy was shocking? Not bad for over 2,000 years ago.


This article originally appeared five years ago.

Carl Sagan's keynote address at the 5th Emerging Issues Forum at NCSU.

Carl Sagan, the legendary astrophysicist and science communicator, was best known for his incredible ability to express complicated concepts in a way that the everyday person could understand. He did so most notably as host of PBS’s groundbreaking “Cosmos: A Personal Voyage" from 1980 to 1981.

Sagan was also a brilliant futurist who was way ahead of his time. In 1961, he predicted that the clouds of Venus might be home to life, an idea that has gained traction over the past few years. He also predicted many of America's current problems in 1995 and correctly claimed that one day AI would be used for psychotherapy back in the '70s.

He was also ahead of his time when sounding the alarm about Climate Change, evidenced by a 1990 speech he gave at the 5th Emerging Issues Forum. In the keynote address, he said that America should treat the climate crisis as seriously as it did the Cold War. Sagan’s speech was delivered a year after the fall of the Berlin Wall, which concluded the icy, 5-decade conflict between the U.S. and the Soviet Union.

For some context, in 1990, only 30% of Americans were worried about global warming or the greenhouse effect. Today, 54% describe climate change as a “major threat” to the country’s well-being.

- YouTubeyoutu.be

“The amount of money that the United States has spent on the Cold War since 1945 is approximately 10 trillion dollars,” Sagan says, adding that with that amount of money, one could own everything in the country, minus the land.

“How certain was it that the Russians were going to invade? Was it 100% certain? Guess not since they never invaded. What if it was only, let’s say 10% certain? What would advocates of big military buildup have said? We must be prudent. It’s not enough to count on only the most likely circumstance," Sagan continues.

“I ask my friends who are comfortable with that argument, including the editorial page of the Wall Street Journal, why doesn’t that same argument apply to Global Warming? You don’t think it’s 100% likely? Fine. You are entitled to think that. If it’s only a small probability of it happening since the consequences are so serious, don’t you have to make some serious investment to prevent it or mitigate it? I think there’s a double standard of argument working and I don’t think we should permit it.”



Sagan would then list the steps we can take to mitigate the effects of climate change, including eliminating CFCs (chlorofluorocarbons), increasing fuel efficiency in cars and trucks, seeking out new alternative energy sources, dealing with the global population crisis and planting trees. "A tree is an engine for taking carbon dioxide out of the atmosphere and it does it. It’s not the only thing a tree does, but that is one of the things that trees are good for and it's especially relevant to this issue,” Sagan says.

Sagan’s solutions are the same ones we discuss today, although fears of a global population crisis have waned over the years.

Sagan concluded his address by comparing the dangers of global warming to those faced by the U.S. during the Cold War and making an argument that many support today: fighting climate change is also good economic policy.

"So, what I say to those who complain that it is too uncertain–beyond pointing out the standards that were applied to the Cold War ought to be applied here–I say look, every one of these steps makes good sense, makes good economic sense,” Sagan says. “And think of all of the industries that are implied by what I have just said, especially alternative energy sources. There is money to be made in developing a technology which will appropriately address greenhouse warming."

You can watch the entire address here:

- YouTubewww.youtube.com

via David Grinspoon / YouTube

In 1989, CNN founder Ted Turner asked iconic astrophysicist and science communicator Carl Sagan about his political leanings.

Surely, someone with such a deep understanding of the universe and a passion for humanism would have important insights into how we organize ourselves politically.

"Are you a socialist?" Turner asked Sagan. "I'm not sure what a socialist is," he replied.


While it seems unlikely Sagan was unfamiliar the concepts of socialist political theory, he was smart to sidestep the loaded term.

Socialism is such a broad concept that, in the modern era, it could be applied to numerous countries of varied economic development from Cuba to Canada. Conservatives tend to see it as a malignant political idea and point to Venezuela as a failed socialist state.

While many liberals point to Democratic Socialist countries in Europe such as Denmark and Germany where people have a standard of living that is comparable and, in some ways superior, to the United States.

Back in the '80s "socialist" was used by the U.S.S.R. to describe its totalitarian communist regime, so Sagan was smart to distance himself with any association with the bloc.

Ted Turner asks Carl Sagan if he is a socialist.www.youtube.com

So Sagan provided his own definition.

"But I believe the government has a responsibility to care for the people," he said.

"I'm talking about making people self-reliant, people able to take care of themselves," he continued. "There are countries which are perfectly able to do that. The United States is an extremely rich country, it's perfectly able to do that. It chooses not to. It chooses to have homeless people."

He also noted that in 1989 we were 19th in infant mortality. "We are 19th in the world in infant mortality. Eighteen other countries save the lives of babies better than we. How come?" Sagan asked, rhetorically.

Sadly, things have only gotten worse over the past 31 years. The U.S. is currently ranked 47 infant mortality.

"They just spend more money on them," said Sagan. "They care about their babies more than we care about ours. I think it's a disgrace."

Sagan also believed that the U.S.'s priorities are completely mixed up. We have a hard time helping our most vulnerable citizens, but we still have enough money to pay for high-priced weapons systems.

"Just look at what something like 'Star Wars,'" Sagan said, pointing to a costly '80s defense program. "We've already spent $20 million on it. And if these guys are permitted to go ahead, they will spend a trillion."

31 years later, things haven't improved, we're near an all-time high in military spending at a time when the world has never been more peaceful.


"Think of what that money could be used for: to educate, to help, to bring people up to a sense of self-confidence," Sagan added.

"To improve not just the happiness of people in America, but their economic standing, to improve the competitiveness of the US compared to other countries. We are using our money for the wrong stuff."


This article originally appeared on 10.5.20

via YouTube

Over the past few years, there has been a growing number of people who believe the Earth is flat. A recent YouGov survey of more than 8,000 Americans found that as many as one in six are "not entirely certain the world is round."

Maybe there wouldn't be so much scientific illiteracy in this world if we still had Carl Sagan around.

Sagan hosted the original version of TV's "Cosmos" in 1980. It would be revived in 2014 with astrophysicist Neil deGrasse Tyson at the helm.


In the first episode of "Cosmos," Sagan easily proved the Earth was a sphere using a piece of cardboard, some sticks, and the work of an ancient Libyan-Greek scholar, Eratosthenes.

Carl Sagan explains how Eratostenes knows the earth is curvewww.youtube.com

"How could it be, that at the same moment, a stick in Syene would cast no shadow and a stick in Alexandria, 800 km to the north, would cast a very definite shadow? Sagan asked.

"The only answer was that the surface of the Earth is curved," he added. "Not only that but the greater the curvature, the bigger the difference in the length of the shadows."

Considering the distance between the two cities and the lengths of the shadows they produced, Eratosthenes was able to determine that the Earth had a seven-degree curve. He used that calculation to speculate the Earth was 25,000 miles in circumference.

These days we know that the earth is 24,860 in circumference, so Eratosthenes was 140 miles off, not bad for over 2,000 years ago.


This article originally appeared on 7.22.20