Month: May 2023

Researchers at a Tokyo university say their vaccine slowed the ageing process in mice, and could even aid the treatment of ageing-related diseases.

What if you could live forever? It’s a question long pondered by fictional supervillains and Silicon Valley billionaires alike.

Now researchers in Japan say they may have taken a step toward boosting human longevity with successful trials of a vaccine against the cells that contribute to the ageing process.

In laboratory trials, a drug targeting a protein contained in senescent cells – those which have naturally stopped reproducing themselves – slowed the progression of frailty in older mice, the researchers from Tokyo’s Juntendo University said.

The vaccine also successfully targeted the senescent cells in fatty tissue and blood vessels, suggesting it could have a positive impact on other medical conditions linked to ageing.

"We can expect that (the vaccine) will be applied to the treatment of arterial stiffening, diabetes and other ageing-related diseases," Juntendo professor Toru Minamino told Japan’s Jiji news agency.

What is cellular senescence?

Cells become senescent when they stop duplicating themselves, often in response to naturally-occurring damage to their DNA. Cellular senescence is thought to contribute to the ageing process itself, as well as ageing-related diseases like Alzheimer’s and some cancers.

"Senescent cells secrete a series of factors that disrupt the function of the tissue," Dr Salvador Macip, head of the University of Leicester’s Mechanisms of Cancer and Ageing Lab, told Euronews Next.

"They ‘call’ cells from the immune system, in theory to be cleared by them (but that eventually fails) and create a chronic low level inflammation, mixed with fibrosis," Macip said.

Macip was part of an international team of academics from universities in the UK, Spain, Nigeria and Saudi Arabia that published research on another method of tackling senescent cells in October this year.

"The biological process of ageing is very complex, therefore it is unlikely that one single strategy will completely stop it or reverse it. However, there are probably many ways to slow it down, and clearing senescent cells seems to be one of the easiest and potentially more effective," he said.

The limit on lifespan

In laboratory tests, preventing the build-up of senescent cells extended the lifespan of mice by 15 per cent, Macip told Euronews Next. Other, similar experiments have achieved as much as a 35 per cent increase, he said.

But before you get too excited, it’s worth bearing in mind that researchers still don’t know how much a living creature’s lifespan can be extended.

"This is a very interesting question, and one that we still have not agreed upon. Some believe there is a ‘hard’ limit for human lifespan (around 130 years is the current estimate), while others think that, on paper, immortality should be feasible," Macip said.

"It’s still early to know how much life can be extended and whether there’s a limit or not".

We may not have to wait too long for an answer, though.

"The field of anti-ageing research is advancing very fast. In the last decade, there have been many key discoveries," Macip said.

"The person that will take the first anti-ageing pill has probably already been born".

Source: https://www.euronews.com/next/2021/12/14/can-we-live-forever-new-anti-ageing-vaccine-could-bring-immortality-one-step-closer

The James Webb Space Telescope (JWST) has discovered the first evidence that millions of supermassive stars up to 10,000 times the mass of the sun may be hiding at the dawn of the universe.

Born just 440 million years after the Big Bang, the stars could shed light on how our universe was first seeded with heavy elements. Researchers, who dubbed the giant stars "celestial monsters," published their findings May 5 in the journal Astronomy and Astrophysics.

"Today, thanks to the data collected by the James Webb Space Telescope, we believe we have found a first clue of the presence of these extraordinary stars," lead study author Corinne Charbonnel, an astronomy professor at the University of Geneva in Switzerland, said in a statement.

Related: The early universe was crammed with stars 10,000 times the size of our sun, new study suggests

The researchers found chemical traces of the gigantic stars inside globular clusters — clumps of tens of thousands to millions of tightly packed stars, many of which are among the most ancient to have ever formed in our universe. Roughly 180 globular clusters dot our Milky Way galaxy and, because they are so old, serve astronomers as windows through time into the earliest years of our universe.

Mysteriously, some of the stars in these clusters have wildly different proportions of elements (oxygen, nitrogen, sodium and aluminum) despite forming at roughly the same time and from the same gas and dust clouds 13.4 billion years ago.

Astronomers believe this elemental variety could be explained by the existence of supermassive stars — cosmic giants born in the denser conditions of the early universe that burned their fuel at much higher temperatures, producing heavier elements that subsequently "polluted" smaller infant stars (which usually consist of much lighter elements).

But finding these stars has proven difficult. Anywhere between 5,000 to 10,000 times the size of our sun, the fiery giants burned at temperatures of 135 million degrees Fahrenheit (75 million degrees Celsius). As bigger, brighter and hotter stars die out the fastest, these cosmic monsters have long since met their demise in extremely violent explosions called hypernovas.

"Globular clusters are between 10 and 13 billion years old, whereas the maximum lifespan of superstars is two million years. They therefore disappeared very early from the clusters that are currently observable. Only indirect traces remain," co-author Mark Gieles, a professor of astrophysics at the University of Barcelona, said in the statement.

To spot the scattered chemical residue of the ancient monsters, the researchers trained the JWST’s infrared camera on the galaxy GN-z11, which is one of the most distant and ancient galaxies ever discovered, sitting 13.3 billion light-years away from Earth. Different chemicals absorb and emit light at different frequencies, so by breaking down the light coming from different globular clusters found across GN-z11, the astronomers discovered that not only were its stars tightly packed but they were surrounded by high levels of nitrogen.

"The strong presence of nitrogen can only be explained by the combustion of hydrogen at extremely high temperatures, which only the core of supermassive stars can reach," Charbonnel said.

Having found the first clues for the celestial monsters, the researchers will look across more globular clusters in more galaxies to see if their discovery holds elsewhere.

Source: https://www.livescience.com/space/cosmology/james-webb-telescope-finds-evidence-of-celestial-monster-stars-the-size-of-10000-suns-lurking-at-the-dawn-of-time

The James Webb Space Telescope took its first close look at a "mini-Neptune" — the most common type of planet beyond our solar system — and found signs of water.

Astronomers have finally peered past the clouds on the exoplanet GJ 1214b, a mini-Neptune planet around a star about 40 light-years away. Mini-Neptunes, like a shrunken down version of the familiar gas giant, are a common type of planet in our galaxy — but because there isn’t one in our own solar system, these worlds have largely remained a curiosity for scientists.

Previous observations of the distant planet were foiled by thick cloud layers, but the powerful James Webb Space Telescope’s (JWST) infrared heat vision allowed astronomers to find a new view through the haze. The results, published May 10 in the journal Nature, reveal that GJ 1214b has an atmosphere made of steam, hinting at its past as a possible "water world," according to NASA researchers.

"For the last almost decade, the only thing we really knew about this planet was that the atmosphere was cloudy or hazy," Rob Zellem, an exoplanet researcher at NASA’s Jet Propulsion Lab, said in a statement. The team used JWST’s Mid-Infrared Instrument (MIRI) to map the temperature of the planet as it moved through its orbit, capturing information on both its day and night sides and enabling astronomers to figure out what it’s made of.

The temperature on GJ 1214b shifted dramatically from day to night, getting as hot as 535 degrees Fahrenheit (280 degrees Celsius) and then cooling down by more than 100 degrees F at night. Imagine a day on Earth with sweltering heat during the day, and then a blizzard overnight — that’s what a 100-degree difference would look like here! On GJ 1214b, this huge temperature swing indicates that the planet’s atmosphere can’t be just light hydrogen molecules; instead, there has to be something else like water or methane. Researchers see this finding as an interesting clue into the planet’s past, since the atmosphere doesn’t match what the star is made of.

GJ 1214b "either lost a lot of hydrogen, if it started with a hydrogen-rich atmosphere, or it was formed from heavier elements to begin with — more icy, water-rich material," lead study author Eliza Kempton, a University of Maryland astronomer, said in the statement. "The simplest explanation, if you find a very water-rich planet, is that it formed farther away from the host star," she added.

Astronomers still have a lot left to figure out about GJ 1214b, but they hope to observe more mini-Neptunes with JWST in the near future. According to Kempton, they hope to figure out a "consistent story" for how mini-Neptunes are created, and how this particular one ended up with so much water.

Source: https://www.livescience.com/space/exoplanets/james-webb-telescope-discovers-ancient-water-world-in-nearby-star-system

[There's a photo of it at the source link below as well as a map of where it travels. Jan]

Over the last few weeks, an enormous balloon has been spotted circling Earth’s Southern Hemisphere in the upper reaches of the atmosphere, sparking fears that it may be a spy balloon like the UFOs that were shot down above North America in February.

But the massive floating bubble is actually NASA’s latest telescope, the Super Pressure Balloon Imaging Telescope (SuperBIT). And rather than spying on unsuspecting people below, the telescope is peering into the cosmos above in search of dark matter.

The giant balloon, which is wider than a football field, was launched on April 16 from Wānaka, New Zealand and has since completed more than two full revolutions around the Southern Hemisphere — the longest continuous flight for a balloon-borne telescope, according to a NASA statement(opens in new tab).

On May 6, photographer Erwin Enrique Sandoval captured a crisp image of SuperBIT around 25 miles (40 kilometers) above Coyhaique in southern Chile. "We could see it high in the afternoon sky," Sandoval told Spaceweather.com(opens in new tab). "It was very large."

SuperBIT’s primary goal is to search for evidence of dark matter by taking detailed images of galaxies in order to spot signs of gravitational lensing — the phenomenon where light from a distant galaxy gets magnified as it travels through gravitationally warped space-time around a closer galaxy — that could provide clues about the invisible yet abundant matter’s true identity.

A new study, released April 20 in the journal Nature Astronomy(opens in new tab), revealed that light from oddly-warped "Einstein rings" could shed light on dark matter’s true identity.

At its lofty altitude, SuperBIT sits above 99.2% of Earth’s atmosphere, which means there is little to no air to obscure its view of the stars, according to the SuperBIT website(opens in new tab). At this height, the telescope can also capture images by day or night.

Astronomers believe the data collected by SuperBIT is comparable in quality to the Hubble Space Telescope, according to Spaceweather.com. And the balloon-borne telescope has already captured several stunning shots(opens in new tab) of distant galaxies.

But astronomy is not the only possible use for giant balloons like this. In June 2020, space tourism company Space Perspective released its plans to eventually take civilians to the edge of space using similar balloons.

Keen-eyed observers and astronomy enthusiasts could have plenty more chances to catch a glimpse of the balloon. "Hopefully, we’ll complete many more revolutions about the hemisphere over the next several weeks," Debbie Fairbrother(opens in new tab), chief of NASA’s Scientific Balloon Program Office, said in the statement. (A single revolution could take anywhere between one and three weeks depending on wind patterns.)

Source: https://www.livescience.com/space/astronomy/weird-balloon-circling-the-southern-hemisphere-isnt-a-spy-craft-its-nasas-newest-telescope

[However, to be exact, it wasn't big. It was only 1 foot long but it was totally bizarre. Jan]

Here’s the video: https://www.youtube.com/watch?v=frnio8eSFyk

Astronomers have observed a radiation belt outside the solar system for the first time, imaging high-energy particles trapped by a magnetic field around an ultra-cool dwarf star around 18 light-years from Earth.

The newfound radiation belt is double-lobed, just like the radiation belts that encircle Jupiter, the largest planet in the solar system. But if the dwarf star’s radiation belt were placed next to that of Jupiter, it would be 10 million times brighter.

The radiation is in the form of persistent, intense radio emissions. Imaging revealed the presence of a cloud of high-energy electrons trapped in the magnetic field of the dwarf star, which is known as LSR J1835+3259.

"We are actually imaging the magnetosphere of our target by observing the radio-emitting plasma  —  its radiation belt  —  in the magnetosphere," research lead author and University of California, Santa Cruz postdoctoral fellow Melodie Kao said in a statement(opens in new tab). "That has never been done before for something the size of a gas giant planet outside of our solar system."

Related: Listen to the terrifying rumble of Earth’s magnetic field being assaulted by a solar storm

The first image of a radiation belt outside the solar system, which was captured using 39 radio telescopes to create a virtual telescope spanning the globe from Hawaii to Germany.

The first image of a radiation belt outside the solar system, which was captured using 39 radio telescopes to create a virtual telescope spanning the globe from Hawaii to Germany. (Image credit: Melodie Kao, Amy Mioduszewski)
The image was captured by the team using a network of 39 radio telescopes, which combined to form a single virtual telescope called the High Sensitivity Array.

LSR J1835+3259 was the only object beyond the solar system that Kao was confident could be observed with enough detail to resolve its radiation belts. And, because the dwarf star has a mass that lies between low-mass stars and brown dwarfs — objects often referred to as "failed stars" because they lack the mass needed to initiate nuclear fusion at their cores — the new observations could help astronomers find the dividing line between small stars and large planets.

"While the formation of stars and planets can be different, the physics inside of them can be very similar in that mushy part of the mass continuum connecting low-mass stars to brown dwarfs and gas giant planets," Kao said.

Strong magnetic fields form a magnetic bubble around a planet called a magnetosphere, which can trap and accelerate charged particles to speeds approaching that of light. Many planets in the solar system have magnetospheres, as does the sun. Even one solar system moon — the huge Jovian satellite Ganymede  —  has a magnetosphere.

Magnetospheres come with different strengths and different characteristics, however. For example, the magnetosphere of Mercury, the closest planet to the sun, has only around 1% the strength of Earth’s magnetic bubble, which is strong enough to protect our planet’s atmosphere and life from highly energetic charged particles from the sun. After the sun, Jupiter has the strongest magnetic field in the solar system.

All the planets in the solar system with magnetic fields also have radiation belts consisting of trapped high-energy charged particles around them. While the radiation belts of Earth, known as the Van Allen Belts, are donut-shaped bands of high-energy particles from solar wind, the majority of the particles trapped by magnetic fields around Jupiter creating double lobe-shaped radiation belts come from its volcanic moon Io.

Regardless of their origin, these trapped particles are deflected by magnetic fields toward the poles of planets, generating auroras. On Earth, these take the form of the northern and southern lights here, or the aurora borealis and the aurora australis, respectively.

The image of LSR J1835+3259 taken by Kao and her team also marks the first time for a body beyond the solar system that the location of an object’s aurora and that of its radiation belts has been successfully differentiated.

Auroras can be used to measure the strength of magnetospheres, if not their shape, so the findings could help determine the strength of the magnetic fields of other dwarf stars, something which is largely unknown currently. Building the theoretical understanding of the magnetic fields of these intermediate-mass objects could, in turn, shed light on the magnetospheres of exoplanets.

"Now that we’ve established that this particular kind of steady-state, low-level radio emission traces radiation belts in the large-scale magnetic fields of these objects, when we see that kind of emission from brown dwarfs  —  and eventually from gas giant exoplanets  —  we can more confidently say they probably have a big magnetic field, even if our telescope isn’t big enough to see the shape of it," Kao said.

Because Earth’s magnetosphere has been so crucial in protecting life on our planet and allowing it to evolve, scientists theorize that magnetic fields around exoplanets may be key to understanding the habitability of worlds beyond the solar system.

"This is a critical first step in finding many more such objects and honing our skills to search for smaller and smaller magnetospheres, eventually enabling us to study those of potentially habitable, Earth-size planets," research co-author Evgenya Shkolnik, an astrophysics professor at Arizona State University, said in the same statement.

The team’s research was published on Monday (May 15) in the journal Nature.(opens in new tab)

Source: https://www.space.com/dwarf-star-radiation-belt-first-outside-solar-system

[It is amazing how many little moons exist around Saturn. But Saturn is really a planet that is surrounded by the results of massive violence. That's where its rings come from. But all these little moons are an amazing discovery. Jan]

Jupiter’s brief but glorious reign as the planet with the most moons in our solar system came crashing down this week as scientists confirmed the discovery of 62 new moons orbiting Saturn — bringing the ringed planet’s total to a whopping 145 moons.

That’s a decisive leap ahead of Jupiter’s 95 confirmed moons – a total that eclipsed Saturn’s moon count for several months after 12 new moons were officially recognized orbiting Jupiter in late December. Saturn is now the first and only planet in the solar system with more than 100 known moons, according to researchers at the University of British Columbia(opens in new tab) (UBC), who aided in the new discoveries.

The team of international researchers made their detections using data from the Canada-France-Hawaii Telescope on top of Mauna Kea, Hawaii between 2019 and 2021. By analyzing a trove of sequential images taken over 3-hour observation windows, the team identified 62 moons that were previously either too small or too dim to detect. Some of the smaller moons measured just 1.6 miles (2.5 kilometers) wide — a distance smaller than the length of the National Mall in Washington, D.C.

All of the 62 newly detected moons are "irregular moons," meaning they follow distant, elliptical orbits around their host planet and often move in retrograde — or in the opposite direction of Saturn’s rotation. Many of these tiny, oddball moons clump together in similar retrograde orbits, suggesting they may have originated from a larger parent moon that broke apart millions of years ago, according to the researchers.

"As one pushes to the limit of modern telescopes, we are finding increasing evidence that a moderate-sized moon orbiting backwards around Saturn was blown apart something like 100 million years ago," Brett Gladman(opens in new tab), a professor of astronomy and astrophysics at UBC, said in a statement.

The new moons are expected to be recognized later this month by the International Astronomical Union — a group of more than 12,000 scientists responsible for designating celestial bodies, among other things.

Jupiter could not be reached for comment.

Source: https://www.livescience.com/space/saturn/scientists-discover-62-new-moons-around-saturn-raising-total-to-145-the-most-in-the-solar-system

[This issue of oceans on other distant moons is very fascinating. Jan]

A reanalysis of Voyager data suggests that four of Uranus moons may have oceans tucked between their cores and icy crusts.

Hidden oceans may lurk under the icy crusts of four of Uranus’ moons.

Scientists recently reanalyzed data from the Voyager spacecraft that flew by Uranus in the 1980s and found that four of Uranus’ largest moons — Ariel, Umbriel, Titania and Oberon — may be warm enough to host liquid oceans. In Titania and Oberon, these oceans might even be warm enough to potentially support life, according to a recent study in the Journal of Geophysical Research(opens in new tab).

"When it comes to small bodies — dwarf planets and moons — planetary scientists previously have found evidence of oceans in several unlikely places, including the dwarf planets Ceres and Pluto, and Saturn’s moon Mimas," study lead author Julie Castillo-Rogez(opens in new tab) of NASA’s Jet Propulsion Laboratory in Southern California said in a statement(opens in new tab). "So there are mechanisms at play that we don’t fully understand."

The new study integrated 1980s Voyager 2 data with information on other icy moons such as Pluto’s Charon and Saturn’s Enceladus drawn from more recent NASA missions such as Galileo, Cassini, Dawn, and New Horizons. Uranus has 27 moons, but the researchers focused on the five largest, which are Ariel, Umbriel, Titania, Oberon and Miranda. Of these, Ariel is the smallest at 720 miles (1,160 kilometers) across, while Titania is the largest at 980 miles (1,580 km) across.

Previously, scientists thought only Tatiana was likely to generate any internal heat via radioactive decay — the process by which unstable atoms lose energy through radiation — believing the other moons to be too small. However, modeling the other moons’ porosity suggested that all but Miranda are insulated enough to retain internal heat created by radioactive decay. The researchers also found that any potential oceans beneath the icy crusts of these moons would be rich in chlorides, ammonia and salts, both of which would lower the freezing point of the water. The combination of a low freezing point and enough internal heat could mean that Ariel, Umbrial, Titania and Oberon all have oceans dozens of miles deep within their interiors, the researchers reported.

In 2020, scientists detected some evidence of recent geological activity on Ariel, suggesting the possible movement of a potential inner ocean. Miranda also has surface features that look relatively fresh, according to the researchers, but their modeling suggests that if the moon did have a liquid ocean at some point, it is likely frozen by now.

To find out if these hidden oceans really exist, scientists will have to get creative. Spectrometers that can detect wavelengths of light reflected by ammonia and chlorides could help prove the presence of these chemicals under the crusts. Scientists could also use instruments that can detect electrical currents carried by liquid water to probe beneath these moons’ surfaces. New modeling studies on how these moons formed could also help researchers plan what kind of observations they will need to make in the future, Castillo-Rogez said.

"We need to develop new models for different assumptions on the origin of the moons in order to guide planning for future observations," she said.

Source: https://www.livescience.com/space/uranus/4-of-uranus-biggest-moons-have-secret-underground-oceans-new-study-suggests

[The James Webb telescope is advancing astronomy at an insane pace. This is the first ever photo of an asteroid belt outside of our solar system. You can view the photo at the source link at the bottom. Jan]

The debris structures around the star Fomalhaut are more complex than comparable features in our own solar system.

NASA’s James Webb Space Telescope captured this image of the dusty debris disk surrounding the young star Fomalhaut using its Mid-Infrared Instrument. The image reveals three nested belts extending out to 14 billion miles (23 billion kilometers) from the star. The inner belts were revealed by Webb for the first time.

The first asteroid belt ever found outside the solar system is more complex than expected, new observations by the James Webb Space Telescope (JWST) reveal.

Astronomers used JWST to examine the dusty ring system around Fomalhaut, a young, hot star that lies about 25 light-years from Earth and is visible with the naked eye in the constellation Piscis Austrinu, the Southern Fish.

Fomalhaut’s ring system consists of three nested belts that extend out for around 14.3 billion miles (23 million kilometers) — about 150 times the distance between Earth and the sun. The rings are more complex than either the Kuiper Belt, a ring of frigid bodies beyond Neptune, or the main asteroid belt, which sits between Jupiter and Mars, the new JWST observations show.

Annotated version of an image captured by NASA’s James Webb Space Telescope showing the dusty debris disk surrounding the young star Fomalhaut, The image reveals three nested belts extending out to 14 billion miles (23 billion kilometers) from the star. The inner belts were revealed by Webb for the first time.

Astronomers discovered a dusty structure surrounding Fomalhaut in 1983 using NASA’s Infrared Astronomical Satellite. Yet the two inner belts of this system had never been sighted before this observation with the JWST.

The dust belts around the young star are thought to be debris from collisions between larger bodies like asteroids and comets, and are therefore referred to as "debris disks." These disks are different than protoplanetary disks, which hold material that later gloms together to form planets. Debris disks form later, after planets are in place.

"I would describe Fomalhaut as the archetype of debris disks found elsewhere in our galaxy, because it has components similar to those we have in our own planetary system," András Gáspár of the University of Arizona, the lead author of a study announcing the new results, said in a statement(opens in new tab).

"By looking at the patterns in these rings, we can actually start to make a little sketch of what a planetary system ought to look like —  if we could actually take a deep enough picture to see the suspected planets," Gáspár added.

Fomalhaut’s outermost belt, which is twice as large as the Kuiper Belt, has been imaged previously by the Hubble Space Telescope, the Herschel Space Observatory and the ground-based Atacama Large Millimeter/submillimeter Array (ALMA). None of those instruments were able to see the interior structure within the outer belt, however.

"Where the JWST really excels is that we’re able to physically resolve the thermal glow from dust in those inner regions. So you can see inner belts that we could never see before," study team member Schuyler Wolff, also of the University of Arizona, said in the same statement.

Going forward, astronomers hope to image debris disks like Fomalhaut’s around other stars using JWST.

"With Hubble and ALMA, we were able to image a bunch of Kuiper Belt analogs, and we’ve learned loads about how outer disks form and evolve," Wolff continued. "But we need the JWST to allow us to image a dozen or so asteroid belts elsewhere. We can learn just as much about the inner warm regions of these discs as Hubble and ALMA taught us about the colder outer regions."

Just like Jupiter dominates the main asteroid belt and Neptune sculpts the Kuiper Belt, astronomers believe that debris disks outside the solar system may be shaped by unseen planets. That means there may well be a planet or two lurking in the rings around Fomalhaut.

"We definitely didn’t expect the more complex structure with the second intermediate belt and then the broader asteroid belt," Wolff said. "That structure is very exciting, because any time an astronomer sees a gap and rings in a disk, they say, ‘There could be an embedded planet shaping the rings!’"

One feature already spotted by JWST in the rings may indicate the presence of forming protoplanets. The team saw what Gáspár labeled "the great dust cloud," which may point to a collision in the outer ring of Fomalhaut between two "under construction" infant planets. This feature could therefore be an expanding cloud of very fine dust particles from two icy bodies that smashed into each other.

A similar feature was spotted in the same ring by Hubble back in 2008. It had dissipated by the time the space telescope reexamined the ring system in 2014, researchers said.

Deeper investigations of more systems like Fomalhaut with JWST could reveal how planets move through these pancake-flat disks. Observing the dust cloud itself, meanwhile, could reveal details about the structure of planetary systems other than our own. This includes discovering what their asteroids — which are much too small to see even with powerful instruments like JWST or Hubble — are like, and if they are similar to the space rocks that swirl around our star and its planets.

The team’s research was published online Monday (May 8) in the journal Nature Astronomy(opens in new tab).

Source: https://www.space.com/james-webb-space-telescope-fomalhaut-asteroid-belt-photo

[This is a fascinating little analysis. I used to think, long ago, that the pyramids were too big to easily have been built, but archaeologists have found the places where the workers lived and they even found the diary of someone who worked on the pyramids. It's actually fascinating. The pyramids were built by professionals and there are modern stone masons in Europe who use techniques that are similar to what had to be used on the pyramids. Much of what was done is not as mysterious as you might think once you understand what stonemasons can do. The estimates herein are relatively accurate. Jan]

GIVEN THAT SOME 4,600 years have elapsed since the completion of the Great Pyramid of Giza, the structure stands remarkably intact. It is a polyhedron with a regular polygon base, its volume is about 2.6 million cubic meters, and its original height was 146.6 meters, including the lost pyramidion, or capstone. We may never know exactly how the pyramid was built, but even so, we can say with some confidence how many people were required to build it.

We must start with the time constraint of roughly 20 years, the length of the reign of Khufu, the pharaoh who commissioned the construction (he died around 2530 B.C.E.). Herodotus, writing more than 21 centuries after the pyramid’s completion, was told that labor gangs totaling 100,000 men worked in three-month spells a year to finish the structure in 20 years. In 1974, Kurt Mendelssohn, a German-born British physicist, put the labor force at 70,000 seasonal workers and up to 10,000 permanent masons.

These are large overestimates; we can do better by appealing to simple physics. The potential energy of the pyramid—the energy needed to lift the mass above ground level—is simply the product of acceleration due to gravity, mass, and the center of mass, which in a pyramid is one-quarter of its height. The mass cannot be pinpointed because it depends on the specific densities of the Tura limestone and mortar that were used to build the structure; I am assuming a mean of 2.6 metric tons per cubic meter, hence a total mass of about 6.75 million metric tons. That means the pyramid’s potential energy is about 2.4 trillion joules.

To maintain his basal metabolic rate, a 70-kilogram (154-pound) man requires some 7.5 megajoules a day; steady exertion will raise that figure by at least 30 percent. About 20 percent of that increase will be converted into useful work, which amounts to about 450 kilojoules a day (different assumptions are possible, but they would make no fundamental difference). Dividing the potential energy of the pyramid by 450 kJ implies that it took 5.3 million man-days to raise the pyramid. If a work year consists of 300 days, that would mean almost 18,000 man-years, which, spread over 20 years, implies a workforce of about 900 men.

Sweat Equity

SHEER HUMAN MUSCLE CAN RAISE A GREAT PYRAMID BECAUSE MOST OF THE MASS IS NEAR THE BOTTOM AND THE WORK CAN BE DIVIDED AMONG THOUSANDS OF PEOPLE AND DISTRIBUTED OVER DECADES. IT WAS THUS NO GREAT DRAIN ON NATIONAL RESOURCES—AND THINK OF THE SPIN-OFF EFFECTS!

A similar number of workers might be needed to place the stones in the rising structure and then to smooth the cladding blocks (many interior blocks were just rough-cut). And in order to cut 2.6 million cubic meters of stone in 20 years, the project would have required about 1,500 quarrymen working 300 days a year and producing 0.25 cubic meter of stone per capita. The grand total of the construction labor would then be some 3,300 workers. Even if we were to double that number to account for designers, organizers, and overseers and for labor needed for transport, tool repair, the building and maintenance of on-site housing, and cooking and laundry work, the total would be still less than 7,000 workers.

During the time of the pyramid’s construction, the total population of the late Old Kingdom was 1.5 million to 1.6 million people, and hence such a labor force would not have been an extraordinary imposition on the country’s economy. The challenge was to organize the labor, plan an uninterrupted supply of building stones, and provide housing, clothing, and food for labor gangs on the Giza site.

In the 1990s, archaeologists uncovered a cemetery for workers and the foundations of a settlement used to house the builders of the two later pyramids at the site, indicating that no more than 20,000 people lived there. That an additional two pyramids were built in rapid succession at the Giza site (for Khafre, Khufu’s son, starting at 2520 B.C.E., and for Menkaure, starting 2490 B.C.E.) shows how quickly early Egyptians mastered the building of pyramids: The erection of those massive structures became just another series of construction projects for the Old Kingdom’s designers, managers, and workers. If you build things, it becomes easier to build things—a useful lesson for those who worry about the sorry state of our infrastructure.

This article appears in the June 2020 print issue as “Building the Great Pyramid.”

Source: https://spectrum.ieee.org/how-many-people-did-it-take-to-build-the-great-pyramid