upworthy

science

via Carl Sagan Planetary Society/Wikimedia Commons and John Finkelstein/Pexels

Carl Sagan used a sliced apple to perfectly explain the fourth dimension.

The concept of the fourth dimension seems beyond human comprehension. As three-dimensional beings, we are unable to see beyond a physical object's height, width and depth. What else could there be? Even if you understand the concept, it is almost impossible to picture it in your mind, which is bound by the limits and realities of the physical world around us.

Enter Carl Sagan, revered as one of the greatest science communicators of his time. Perhaps best known for his research into extraterrestrial life, he was one of the first people to demonstrate that life could have existed on Mars. Sagan possessed a unique gift for demystifying complex scientific concepts, making them accessible and thrilling for the general public. If you never had the pleasure of watching him on television, you could imagine him as something of a Scientific Mister Rogers. Friendly, a wonderful storyteller, and always able to distill difficult lessons into their simplest form.

In 1980, on Episode 10 of the groundbreaking PBS show “Cosmos,” Sagan embarked on a mission to explain the seemingly impossible fourth dimension.


carl sagan, cosmos ,4th dimension, 3-D, 4-D, 2-D, physics, theoretical physics, math, science, space, spacetime, einsteinA great communicator and handsome, to boot.Giphy

Many of us have commonly heard of time being considered the fourth dimension. That's not so hard to understand — in order to locate an object in the universe, you'd need to know three dimensions of its spatial location and also the time during which it exists.

But there is also a more theoretical and harder to understand place, where all four dimensions are spatial. It is nearly impossible for any of us to comprehend... without the help of a gifted teacher.

What’s excellent about Sagan’s explanation is that he uses simple and relatable objects: an apple and a Tesseract, or a hypercube.

carl sagan, cosmos ,4th dimension, 3-D, 4-D, 2-D, physics, theoretical physics, math, science, space, spacetime, einsteinSagan explains that if an apple existed in a 2-dimensional space, anyone living in this "flatland" would only see a cross-section of it at a time.Giphy

"In discussing the large scale structure of the cosmos, astronomers sometimes say that space is curved. Or that the universe is finite but unbound," Sagan begins. "Whatever are they talking about?"

Yeah, this guy gets it.

Sagan then goes on to explain how a two-dimensional being living in a flat world would perceive a three-dimensional object like an apple.

Watch his full explanation here. It's hypnotic and entertaining and incredibly enlightening.

- YouTubewww.youtube.com


“Imagine we live in this ‘Fllatland’/2-D plane with no concept of ‘up’ or ‘down.’ Then along comes a 3-D object like an apple. We do not even notice it until it crosses our plane of existence — and even then, we have no idea what the apple is,” Sagan explains. “We see only a fragment as it passes through our plane. There is no way we can comprehend the 3-D quality/dimension of the apple, because it is more than we can understand. We only have the evidence of what has passed through our plane.”

To further demonstrate, Sagan stamps the apple into an inkpad and then onto the surface in front of him, which represents Flatland and all of its inhabitants. Inside Flatland, the apple exists only as its points of contact on the paper; or four small dots. He adds that as the apple passes through the 2-dimensional Flatland, its cross-section changes. So someone living in that plane of existence would experience the apple as an ever-shifting and rearranging set of shapes or objects. Wild!

Sagan then related this two-dimensional experience of the third dimension to how we might try to understand the fourth. To do so, he used the Tesseract, a four-dimensional cube, to demonstrate how difficult it is for us to perceive or visualize dimensions beyond our own three.

carl sagan, cosmos ,4th dimension, 3-D, 4-D, 2-D, physics, theoretical physics, math, science, space, spacetime, einsteinA tesseract can not exist in 3-dimensional space, but it can be approximated the same way a cube can be drawn on paper.Giphy

Sagan explains that the tesseract is a cube expanded into a 4th dimension, but "I cannot show you a tesseract because I, and you, are trapped in three dimensions." But what he can do is show us a 3-dimensional rendering of one. Just like a cube can be drawn and approximated (or cast a shadow) onto a piece of paper, a 4-dimensional tesseract can be imperfectly represented in 3-dimensional space. Still following?

At this point, Sagan is asking the viewer to expand their minds to understand the fourth dimension metaphorically. Though we cannot see it or even properly visualize it, that doesn't mean that the things we can see can't offer clues and lessons about the fourth dimension.

Studying 4-dimensional space can help in our understanding of the universe around us. Just because we see and experience only three dimensions doesn't mean that's all that exists. It's critical for physicists and mathematicians to be able to understand and map these theoretical spaces to better comprehend things we otherwise can not explain. Remember the ever-changing, rearranging set of shapes as the apple passes through Flatland?

Sagan’s demonstration of the fourth dimension isn’t just a wonderful explanation of a scientific idea that many of us find difficult to comprehend; it’s also a great example of how to teach complex ideas by combining clear explanations, everyday concepts everyone can understand, and brilliant storytelling.

This article originally appeared last year. It has been updated.

Van Gogh's Starry Night, 1889.

Vincent van Gogh never got to enjoy his own historic success as an artist (even though we've been able to imagine what that moment might have looked like). Van Gogh died in 1890 at the age of 37 in Auvers-sur-Oise, France after shooting himself in the chest with a revolver. It was a tragic end to a turbulent life marked by mental instability and severe self-doubt.

According to the Van Gogh Museum, in a letter to his brother Theo in 1890, just a couple of weeks before his death, Van Gogh wrote, "...my life, is attacked at the very root, my step also is faltering." The man was struggling and exhausted. The high standards he had set for himself and his art were taking a toll. He was unsure about his future and, up to this point, had not received much recognition for his work and thought himself a failure "as a man and as an artist."

His most well-known work, Starry Night, was famously painted while Van Gogh was staying in an asylum in France 1889 after he mutilated his ear during a psychotic episode. According to the Van Gogh Museum, though, this may not be the full story. While it is widely agreed that Van Gogh did in fact cut off his own ear, the museum notes that it was because of a fight between Van Gogh and Paul Gaugin, the artist he had been working for in Aries, that led to the violent explosion that highlighted his deteriorating mental state.

Vincent Van Gogh, artist, 19th century, famous artist, Starry NightVincent Van Gogh's Self-Portrait, 1889Image via Canva.

As one of the best known and most studied artists of the 19th century, Van Gogh's madness and how it influenced his work is not new information. But it turns out that those of us who have appreciated his work have been missing out on some critical details for more than 100 years—revealed in the 2010s thanks to the Hubble Space Telescope.

A video at the bottom of the page will explain everything, but before we get there, let's do some backstory:

We known Van Gogh was an artist—and a genius artist at that—but, it turns out, he was also scientist. Kind of.

Whether intentionally or not, fresh eyes have found that Van Gogh's art—aside from being breathtaking—also captures one of science and nature's most elusive concepts: Turbulence.

The concept of turbulence is hard to understand with math, but it turns out art makes it fairly easy to comprehend through depiction. So, what is turbulence?

According to Britannica, turbulence, or turbulent flow, is a concept of fluid dynamics in which a type of fluid flow (liquid or gas like air or water or air) undergoes an irregular fluctuation or energy cascade. In other words, the air or water swirls and eddies as it moves: big eddies make smaller eddies, and those make even smaller ones, and so on. Common examples of turbulent flow include blood flow in arteries, lava flow, atmosphere and ocean currents, and the flow in boat wakes or surrounding the tips of aircraft wings.

It looks like this:

figures, flow, turbulence, turbulent flow, science, movementTurbulent flow illustrated and animated.All Van Gogh GIFs via TED-Ed.

The thing is, scientists only started figuring this out pretty recently.

turbulence, turbulent flow, science, nature, researchAnimation of art referencing science.All Van Gogh GIFs via TED-Ed.

And yet, there was Mr. Vincent van Gogh, 100 years earlier in his asylum with a mutilated ear and able to accurately capture this turbulent flow in what would become his most famous work, Starry Night.

Starry Night, Van Gogh, turbulence, art, art captures scienceAnimated Starry NightAll Van Gogh GIFs via TED-Ed.

The folks who noticed Van Gogh's ability to capture turbulence checked to see whether other artists did the same. Most of the Impressionists achieved "luminance" with their art—a striking and lifelike depiction of light's effect on color. While impressive, they did not capture or depict turbulence the way Van Gogh did.

The Scream, Edvard Munch, art, popular art, history, painting An animated depiction of The Scream.All Van Gogh GIFs via TED-Ed.

Not even Edvard Munch's The Scream, with it's swirling color and movement, could recreate what Van Gogh had accomplished.

Even in his darkest time, Van Gogh was able to capture—with eerie accuracy—one of nature's most complex and confusing concepts 100 years before scientists had the technology to do so.

Who would have thought that the beauty Van Gogh captured was foreshadowing what scientists would observe in the real, natural world in a century's time? To learn even more, watch the TED-Ed video below:

- YouTubeyoutu.be

This article originally appeared twelve years ago. It has been updated.

Why is text reversed in mirrors?

Have you ever wondered why text shows up backwards in a mirror? It's confusing to our brains because it doesn't seem like anything else is flipped like that. If we turn our head, it doesn't move the opposite direction in a mirror. Or does it? After all, right-handed you is actually left-handed you in the mirror. Right? (Wait, is that right?)

Mirrors can be confusing, despite not being very complicated. A mirror image is simply a reflection of what's before it. But when someone else is looking at us head on, they don't see text in reverse, so why don't we see what other people see when we see ourselves in a mirror?

Kitten Aww GIF by MOODMANGiphy

(If you think this is a super stupid question with a super obvious answer, congratulations. Pat yourself on the back and scootch along so the folks who don't fully grasp the physics of mirrors can enjoy a demonstration that makes it a little easier to understand.)

"Why do mirrors reverse text?" asks the creator behind @humanteneleven on YouTube. "You might think it's just a property of mirrors—they flip things from left to right—but that's not true." He then picks up a metal arrow to show that it points the same direction in the mirror as it does in real life. So why is the text flipped when the arrow isn't?

- YouTubewww.youtube.com

He then holds up a book to show how the text on the book cover appears backwards, just like the shirt. But when he holds up a Ziploc bag with the word "HELLO" written on it, the word shows up properly.

That's because he had to flip the book over to see the cover text in the mirror. The baggy he could just hold up and see the letters through the transparent plastic, just as we see them in real life. If he flips the baggy over like he did the book, the text shows up backwards in the mirror, just like it does in real life.

"So it's actually not the mirror that's flipping anything from left to right," he says. "It's the human."

People appreciated the simple, straightforward explanation and demonstrations.

"One of the most insightful demonstrations I've seen. It's simple and explains the phenomenon. Well done!"

"While I've heard this explanation many times before, I've only recently seen it demonstrated with text-on-transparency, which is what really makes it click. Great video!"

"Love these sorts of demonstrations. It’s a bit of a complicated one, but I love seeing how different people's minds work when explaining simple things like this. My kid explains it with “left is on the left, right is on the right, things aren’t flipped, they are mirrored” but it’s true that you are the one who flips things and I’ve never thought of it that way before."

"Oh my God, I haven't understood explanations from physics videos about why mirrors flip but this, gosh this helps."

Mirrors have been hilariously befuddling people in other videos as they try to figure out how the mirror knows what's behind a barrier placed in front of objects.

@sarahcoome

this is kinda creepy 👀 #mirror #relatable #creepy

Is this something all of us should probably have learned in high school? Yes. Do all of us remember everything we learned in high school? No. Does the scientific explanation make perfect sense to everyone even if it's explained in detail? Um, no.

Like the reversed text question, having a simplified explanation that doesn't fully get into the nitty gritty physics and geometry of how mirrors work is helpful for some folks.

- YouTubewww.youtube.com

For those who do want a bit more scientific substance to their explanations, this next video does a good job of giving a bit more detail while still keeping the explanation simple. It even uses a visual diagram to explain:

- YouTubewww.youtube.com

And for those who say, "This is so basic! How do people not understand this?" here's a video that really does get into the nitty gritty physics and geometry of how mirrors work, diving into ray and wave optics, photons, wave functions, probability, and quantum mechanics. It's only 12 minutes, and it manages to entertain while explaining, but it certainly blows the notion that understanding mirrors is super simple.

- YouTubewww.youtube.com

As one commenter wrote, "I thought I understood mirrors. I understand mirrors even less now. And that's a compliment."

Isn't science fun?


Health

17-year-old launches fascinating "Sperm Racing" league to get people talking about male fertility

"When you really think about it, we all won our own individual sperm races to get onto this planet," one viewer said.

Canva Photos

Ladies and gentlemen, place your bets on the healthiest and most mobile sperm!

At one point or another, we all saw the videos in health class that explained how babies are made. A pivotal scene in these educational films is the inevitable race between sperm as they make their way through the cervix and uterus in a frantic rush to reach the egg before they're destroyed. It's really wild to think about—out of hundreds of millions of sperm released during sex, only one (1!) will successfully penetrate the outer layer of the egg and achieve fertilization.

And even that is not guaranteed. Successful conception requires the right timing and environmental factors in the woman's body, and it also requires strong, healthy, mobile sperm. The odds are long, and only the best can survive!

It's a wonder it took someone so long to come up with the brilliant idea: Sperm races!

sperm, sexual health, fertility, infertility, men, men's health, mens fertility, sexAnd they're off to the races!Giphy

A 17-year-old "student and entrepreneur" from California named Eric Zhu recently had the idea to pit men against each other to see who had the healthier, stronger sperm.

The whole thing has the atmosphere of a supercharged UFC fight. There's a live crowd, a pre-match weigh in, professional hype crew. There's music and lights. Apparently, if you attend a bout, you can even bet on the results of the race.

After the contestants provide a, uh, sample, the sperm are introduced onto a tiny track that mimics the shape of the female reproductive system complete with "chemical signals, fluid dynamics, and synchronized starts." Using a sophisticated series of microscopes and high-tech cameras, every movement of the sperm are tracked as the two contestant's quite literally race to the finish line.

The "athletes" recruited even train before the big showdown by honing in on their diets, workout routines, and mental discipline.

On stage at the event, the Sperm Racing team showed a video that alleged to represent a real-live sperm race. In reality, reporters later found out, the video shown was merely a 3D representation of a race that had been conducted beforehand behind closed doors.

The authenticity of the race and competition is still up for debate. Still pretty entertaining though if you can suspend your disbelief:

It's complete insanity, with a heavy hand on the marketing and hype. But it's (mostly) for a good cause. Zhu launched Sperm Racing to start a broader conversation around male fertility, which is seeing an alarming decline.

Around the globe, men's sperm quality and counts are suffering, in part due to environmental factors, diet, and more. Fertility is so often seen and discussed as a women's issue, but more men need to know they play an important role. Certain factors are out of our control, but diet, exercise, sleep, stress management, and more can actually play a massive role in sperm quality.

Male infertility is responsible for about half of all infertility, which is what you would expect. But did you know that sperm quantity and quality also play a major role in embryo development, miscarriage risk, birth weight, fetal health, and likelihood of other pregnancy complications? If not, you're not alone. We don't talk about this nearly enough.

sperm, sexual health, fertility, infertility, men, men's health, mens fertility, sexHaving healthy sperm is way more important than most people realize.Giphy

There are some fair criticisms of Sperm Racing, to be clear. Some commenters find the whole thing gross and off-putting, and it's worth questioning why we need to wrap men's health in this hyper-macho, sports-like packaging for people to take it seriously. There's talk on the official Sperm Racing website of setting up an official league, the best competitors becoming professional athletes. "Where legends are born," the eye-rolling manifesto reads. It reeks of the same men who won't get their regular prostate exams because they think it's "gay" (yes, that's really a thing).

And, of course, there are still many questions about the authenticity of the science behind Sperm Racing, and the ethics behind letting people bet on something that may be pre-determined and not actually performed live.

Then again, the whole thing is just so absolutely, absurdly ridiculous that it can't help but generate headlines and grab attention. And maybe that's exactly the point. Having a salad and going for a run to improve your sexual health isn't overly exciting. But training for a chance to win the Sperm Racing championship belt? Now that's guaranteed to get a few reluctant dudes up off the couch, even if they have no real intention of competing.

OSZAR »