Here in our Universe, the light that gets emitted from objects isn’t necessarily the same as the light that arrives in either our eyes or our instruments. Not only are there many intervening effects that can alter a signal on the way — by interacting with fields, by passing through neutral and ionized matter, and by having to compete with sources of noise — but there are kinetic (motion-based) and gravitational (spacetime-based) effects that alter those signals while in transit as well. In particular, three main effects all can systematically shift light of any wavelength toward either redder or bluer wavelengths:
the relative motion of the emitting source and the receiving observer,
the changes in the gravitational field that the traveling signal experiences during its journey,
and the effects of either expansion or contraction of the spacetime through which the signal travels.
These three effects can lead to redshifts or blueshifts, depending on which direction they occur in, and it was long expected that they’d affect all waves, not just light waves, in a similar fashion. Now that we’re in the era of gravitational ... Continue Reading »
Trauma doesn’t end when the danger does, and for decades, science couldn’t explain why.
Rachel Yehuda, a leading PTSD researcher, has spent her career inside that question, uncovering the way that trauma can leave impressions on our genes, sometimes passing biological echoes of those events to the next generation.
Now, she’s focused on MDMA therapy, which could actually break the chain.
This video This isn’t a trip, it’s the most challenging therapy session of your life is featured on Big Think.
Continue Reading »
What determines the extent of employers’ wage-setting power? It boils down to how easily — borrowing Beyoncé’s phrase — you can “release your job” when pay isn’t good enough. But how simple is it for someone to quit Walmart if they are dissatisfied with their wage?
To answer this question, my collaborators Suresh Naidu and Adam Reich and I surveyed about 10,000 Walmart workers in 2019 using a Facebook-based strategy, similar to the Shift Project. As we saw previously, Walmart, the nation’s largest private employer, has long been associated with low pay. In 2019, its voluntary company-wide minimum wage stood at $11 per hour, lagging behind competitors like Target and Costco. If paying jobs were truly easy to replace, one would expect Walmart jobs to be among the easier to quit and move on from, or market pressure would already have pushed Walmart wages to match those competitors.
To make an apples-to-apples comparison, here I focus on roughly 1,300 workers earning exactly $11 in states where that wage was legal (i.e., the state minimum wage was below $11). We asked these workers ... Continue Reading »
With the launch of Artemis II in April of 2026, humans are finally set to add to the historical precedent set in the late 1960s and early 1970s: a return to the Moon. Prior to their expected arrival at our nearest neighboring planetary body, expected to occur after just over a four day journey, a gap of more than 50 years persisted between human visits to the Moon. During the Apollo era, only 24 people ever flew to the vicinity of the Moon, traveling hundreds of thousands of miles from Earth to do so. Twelve of those travelers, on six independent missions, actually set foot on the lunar surface. Many artifacts have been left behind on the Moon during that time: flags, photographs, seismometers, mirrors, and even vehicles, while those same humans brought back rocks, dirt, and actual pieces of the Moon. (An autonomous sample return mission, from the lunar far side, was also conducted by China earlier this decade.)
Of everyone still alive today, fewer than 25% are old enough to have memories of these monumental moments in history: when ... Continue Reading »
For early 16th-century Europeans, this map was a revelation. It showed a previously unknown island metropolis in the recently discovered Americas — an alien Venice, if you will.
However, by the time this first European portrait of the Aztec capital Tenochtitlan was published in 1524, the city, once home to perhaps 200,000 people, was already gone — razed in 1521 by Spanish conquistador Hernán Cortés. In its place, Mexico City would eventually rise.
Yet this is more than the ghost map of a recently deceased city. It is a multi-layered document of first contact, evidence of the hybridization of two clashing cultures as well as the dominance of one over the other.
Curiously, nobody knows who exactly made this map. The leading theory is that it was based on an indigenous chart of the city. Cortés had obtained from the Aztec emperor Montezuma a map of the coastline, so it seems plausible that a native cartographer provided a cartographic outline of the capital, too.
The map shows a city labelled Temixtitan built on islands in Lake Texcoco. Four causeways in the cardinal directions connect ... Continue Reading »
Most people spend years searching for a mentor who will change their life, never realizing the most valuable lessons are already happening around them.
Shark Tank’s Robert Herjavec breaks down why the traditional idea of mentorship is not only outdated, but actively getting in the way of your growth.
This video The hidden reason smart people stop growing is featured on Big Think.
Continue Reading »
There’s a legendary bit of wisdom that applies just as well to theoretical physics as it does to the drug culture from which it arose: “Don’t get high on your own supply.” While theoretical physicists are famous for coming up with extraordinary, creative, exotic scenarios for what may yet be possible in the Universe, there’s a great danger in buying into such an idea, and thinking that it’s likely, before a sufficient amount of supporting evidence has been found in favor of it. This was the fallacy that led to the rise of elegant, beautiful, and compelling scenarios — grand unification, supersymmetry, extra dimensions, and string theory — whose predictions simply don’t appear to match experimental reality in any measurable way.
The danger isn’t in having and developing an idea that’s speculative, but rather in believing in it so strongly that you reach for it as your go-to explanation whenever you see even a tiny hint that could potentially support it. This is the cognitive fallacy of motivated reasoning, and even theoretical physicists, particularly when armed with suggestive-but-inconclusive data, are susceptible ... Continue Reading »
In this monthly issue, we look at resilience not as a buzzword or a self-help prescription, but as a property — one that shows up, or doesn’t, at every scale.
Continue Reading »
In the late 20th century, the world came together to plug a hole in the ozone layer — the part of Earth’s atmosphere that absorbs most of the Sun’s harmful ultraviolet radiation. If left unchecked, this hole would have exposed life on Earth to dangerous — and in some regions potentially lethal — levels of radiation, but an international treaty brought us back from the brink of disaster.
That treaty, the Montreal Protocol, is a lesson in human resilience: We can save the world, because we already did it once before.
An epidemic of deadly fridges
The story of the Montreal Protocol starts, bizarrely, with an epidemic of deadly fridges in the 1920s. In those pioneer days of electric home refrigeration, everyone’s favorite new kitchen appliance relied on highly toxic, flammable, or corrosive gases to keep food chilled. A faulty compressor or leaky pipe could wipe out an entire family in their sleep, and in the first half of 1929, gas from fridges killed at least 15 people in Chicago alone.
Danger drove innovation, and in 1928, General Motors engineer Thomas Midgley Jr. synthesized ... Continue Reading »
Not long ago, I found myself in line at my local dry cleaner. It’s a modest shop, the kind of place you’ve passed a thousand times without a second thought. But the man behind the counter — let’s call him Howard — is not a modest man. He pays an almost fussy, forensic level of attention to every customer. He remembers names and checks garment tags twice. He asks follow-up questions about a persistent wine stain on a lapel that suggest he genuinely, deeply cares about the outcome of his work.
When it was finally my turn at the counter, I thanked him for the meticulousness he brought to his work and casually asked how business had been. Howard sighed. He smiled a weary smile and paused. “Where to start?” he said. Then he told me about 2020.
When the pandemic struck, dry cleaners were among the hardest-hit businesses in the country. It was a perfect storm of obsolescence. Offices shuttered and weddings were canceled. Between remote work and the sudden “Zoom-casual” dress code, the demand for pressed shirts and dry-cleaned suits ... Continue Reading »
Here in our Universe, the light that gets emitted from objects isn’t necessarily the same as the light that arrives in either our eyes or our instruments. Not only are there many intervening effects that can alter a signal on the way — by interacting with fields, by passing through neutral and ionized matter, and by having to compete with sources of noise — but there are kinetic (motion-based) and gravitational (spacetime-based) effects that alter those signals while in transit as well. In particular, three main effects all can systematically shift light of any wavelength toward either redder or bluer wavelengths:
the relative motion of the emitting source and the receiving observer,
the changes in the gravitational field that the traveling signal experiences during its journey,
and the effects of either expansion or contraction of the spacetime through which the signal travels.
These three effects can lead to redshifts or blueshifts, depending on which direction they occur in, and it was long expected that they’d affect all waves, not just light waves, in a similar fashion. Now that we’re in the era of gravitational ... 
What determines the extent of employers’ wage-setting power? It boils down to how easily — borrowing Beyoncé’s phrase — you can “release your job” when pay isn’t good enough. But how simple is it for someone to quit Walmart if they are dissatisfied with their wage?
To answer this question, my collaborators Suresh Naidu and Adam Reich and I surveyed about 10,000 Walmart workers in 2019 using a Facebook-based strategy, similar to the Shift Project. As we saw previously, Walmart, the nation’s largest private employer, has long been associated with low pay. In 2019, its voluntary company-wide minimum wage stood at $11 per hour, lagging behind competitors like Target and Costco. If paying jobs were truly easy to replace, one would expect Walmart jobs to be among the easier to quit and move on from, or market pressure would already have pushed Walmart wages to match those competitors.
To make an apples-to-apples comparison, here I focus on roughly 1,300 workers earning exactly $11 in states where that wage was legal (i.e., the state minimum wage was below $11). We asked these workers ... 
With the launch of Artemis II in April of 2026, humans are finally set to add to the historical precedent set in the late 1960s and early 1970s: a return to the Moon. Prior to their expected arrival at our nearest neighboring planetary body, expected to occur after just over a four day journey, a gap of more than 50 years persisted between human visits to the Moon. During the Apollo era, only 24 people ever flew to the vicinity of the Moon, traveling hundreds of thousands of miles from Earth to do so. Twelve of those travelers, on six independent missions, actually set foot on the lunar surface. Many artifacts have been left behind on the Moon during that time: flags, photographs, seismometers, mirrors, and even vehicles, while those same humans brought back rocks, dirt, and actual pieces of the Moon. (An autonomous sample return mission, from the lunar far side, was also conducted by China earlier this decade.)
Of everyone still alive today, fewer than 25% are old enough to have memories of these monumental moments in history: when ... 
For early 16th-century Europeans, this map was a revelation. It showed a previously unknown island metropolis in the recently discovered Americas — an alien Venice, if you will.
However, by the time this first European portrait of the Aztec capital Tenochtitlan was published in 1524, the city, once home to perhaps 200,000 people, was already gone — razed in 1521 by Spanish conquistador Hernán Cortés. In its place, Mexico City would eventually rise.
Yet this is more than the ghost map of a recently deceased city. It is a multi-layered document of first contact, evidence of the hybridization of two clashing cultures as well as the dominance of one over the other.
Curiously, nobody knows who exactly made this map. The leading theory is that it was based on an indigenous chart of the city. Cortés had obtained from the Aztec emperor Montezuma a map of the coastline, so it seems plausible that a native cartographer provided a cartographic outline of the capital, too.
The map shows a city labelled Temixtitan built on islands in Lake Texcoco. Four causeways in the cardinal directions connect ... 
There’s a legendary bit of wisdom that applies just as well to theoretical physics as it does to the drug culture from which it arose: “Don’t get high on your own supply.” While theoretical physicists are famous for coming up with extraordinary, creative, exotic scenarios for what may yet be possible in the Universe, there’s a great danger in buying into such an idea, and thinking that it’s likely, before a sufficient amount of supporting evidence has been found in favor of it. This was the fallacy that led to the rise of elegant, beautiful, and compelling scenarios — grand unification, supersymmetry, extra dimensions, and string theory — whose predictions simply don’t appear to match experimental reality in any measurable way.
The danger isn’t in having and developing an idea that’s speculative, but rather in believing in it so strongly that you reach for it as your go-to explanation whenever you see even a tiny hint that could potentially support it. This is the cognitive fallacy of motivated reasoning, and even theoretical physicists, particularly when armed with suggestive-but-inconclusive data, are susceptible ... 
In this monthly issue, we look at resilience not as a buzzword or a self-help prescription, but as a property — one that shows up, or doesn’t, at every scale.
In the late 20th century, the world came together to plug a hole in the ozone layer — the part of Earth’s atmosphere that absorbs most of the Sun’s harmful ultraviolet radiation. If left unchecked, this hole would have exposed life on Earth to dangerous — and in some regions potentially lethal — levels of radiation, but an international treaty brought us back from the brink of disaster.
That treaty, the Montreal Protocol, is a lesson in human resilience: We can save the world, because we already did it once before.
An epidemic of deadly fridges
The story of the Montreal Protocol starts, bizarrely, with an epidemic of deadly fridges in the 1920s. In those pioneer days of electric home refrigeration, everyone’s favorite new kitchen appliance relied on highly toxic, flammable, or corrosive gases to keep food chilled. A faulty compressor or leaky pipe could wipe out an entire family in their sleep, and in the first half of 1929, gas from fridges killed at least 15 people in Chicago alone.
Danger drove innovation, and in 1928, General Motors engineer Thomas Midgley Jr. synthesized ... 
Not long ago, I found myself in line at my local dry cleaner. It’s a modest shop, the kind of place you’ve passed a thousand times without a second thought. But the man behind the counter — let’s call him Howard — is not a modest man. He pays an almost fussy, forensic level of attention to every customer. He remembers names and checks garment tags twice. He asks follow-up questions about a persistent wine stain on a lapel that suggest he genuinely, deeply cares about the outcome of his work.
When it was finally my turn at the counter, I thanked him for the meticulousness he brought to his work and casually asked how business had been. Howard sighed. He smiled a weary smile and paused. “Where to start?” he said. Then he told me about 2020.
When the pandemic struck, dry cleaners were among the hardest-hit businesses in the country. It was a perfect storm of obsolescence. Offices shuttered and weddings were canceled. Between remote work and the sudden “Zoom-casual” dress code, the demand for pressed shirts and dry-cleaned suits ...