Science
The Extreme Temperatures of the Universe

The Extreme Temperatures of the Universe
For most of us, temperature is a very easy variable to overlook.
Our vehicles and indoor spaces are climate controlled, fridges keep our food consistently chilled, and with a small twist of the tap, we get water that’s the optimal temperature. Of course, our concept of what’s hot or cold is actually very narrow in the grand scheme of things.
Even the stark contrast between the wind-swept glaciers of Antarctica and the blistering sands of our deserts is a mere blip on the universe’s full temperature range. Today’s graphic, produced by the IIB Studio, looks at the hottest and coldest temperatures in our universe.
But First: What is Temperature Anyway?
Before looking at this top-to-bottom view of extreme temperatures, it helps to remember what temperature is actually measuring – kinetic energy, or the movement of atoms.
Hypothetically, atoms would simply stop moving as they reach absolute zero. As matter heats up, it begins to “vibrate” more vigorously, changing states from solid to gas. Eventually, plasma forms as electrons wander away from the nuclei.
With that quick primer, let’s dig into some of the hottest insights in this cool data visualization.
Highs and Lows on Planet Earth
Earth’s lowest air temperature, -135ºF (-93ºC), was recorded in Antarctica in 2010. Since then, scientists have discovered that surface ice temperatures can dip as low as -144ºF (-98ºC).
The conditions need to be just right: clear skies and dry air must persist for several days during the polar winter. In surroundings this cold, human lungs would actually hemorrhage within just a few breaths.
On the other end of the spectrum of extreme temperatures, the hottest surface reading on Earth of 160ºF (71ºC) occurred in Iran’s Lut Desert in 2005. In fact, the Lut Desert clocked the highest surface temperature in 5 out of 7 years during a 2003-2009 study, making it the world’s hottest location. The desert’s dark pebbles, dry soil, and lack of vegetation create the perfect conditions for blistering heat.
There are very few organisms that can withstand such temperatures, but one fascinating phylum makes the cut.
The Amazing Tardigrade
Commonly known as a “moss pig” or “water bear”, the one-millimeter long tardigrade is extremely resilient. While most organisms need water to survive, the tardigrade gets around this by entering a “tun” state, in which metabolism slows to just 0.01% of its normal rate.
When water is scarce, the creature curls up and synthesizes molecules that lock sensitive cell components in place until re-hydration occurs. Beyond dry conditions, the tardigrade can also survive both freezing and boiling temperatures, high radiation environments, and even the vacuum of space.
This video courtesy of TEDEd explains more about the hardy critter:
Testing the Limits
For better or worse, humans have pushed the limits of temperature here on Earth.
At MIT, scientists cooled a sodium gas to half-a-billionth of a degree above absolute zero. In the words of the Nobel Laureate Wolfgang Ketterle, who co-led the team: “To go below one nanokelvin (one-billionth of a degree) is a little like running a mile under four minutes for the first time.”
Not all experiments are conducted out of simple curiosity. Conventional bombs already explode at around 9,000ºF (5,000ºC), but nuclear explosions take things much further. For a split second, temperatures inside a nuclear fireball can reach a mind-bending 18,000,000ºF (10,000,000ºC).
The highest man-made temperature ever recorded is 9,900,000,000,000ºF (5,500,000,000,000ºC), created in the Large Hadron Collider at CERN in Switzerland. It was achieved by accelerating heavy lead ions to 99% the speed of light and smashing them together.
Highs and Lows of the Universe
While humans have been able to manufacture extremely hot and cold temperatures, the universe has created these extremes naturally.
Undoubtedly, the creation of the universe is made of the hottest stuff of all. The temperature of the universe at 10⁻³⁵ seconds old was a whopping 1 octillion ºC. Moments later, it “cooled down” to 1,800,000,000ºF (1 billion ºC) when the universe was less than two minutes old.
On the other end of the spectrum, the coolest natural place currently known in the universe is the Boomerang Nebula at -457.6ºF (-272ºC). It’s found 5,000 light years away from us in the constellation Centaurus, and it is currently in a transitional phase as a dying star.
As space exploration goes further than ever, these extreme temperatures may one day reach even hotter or colder heights than we can imagine.
Misc
Visualizing the Biomass of All the World’s Mammals
When the world’s biomass—the stuff we’re made of—is tallied up, humans and cattle outweigh wild mammals by a massive margin.

Visualizing the Biomass of All the World’s Mammals
Even as we understand more about the world we live in, certain aspects of it remain undefined or hard to comprehend.
One such example is in the scale and distribution of Earth’s life. What’s the ratio of wild to domesticated animals? How much do all of the world’s humans weigh?
Until recently, such questions were nearly unanswerable. A new report titled The Global Biomass of Wild Mammals helps shed more light on the composition and scale of life on our planet. The research provides an estimate of the biomass of all mammals, globally—including humans.
So, What is Biomass Anyway?
Biomass is simply the weight of living things.
In this study, researchers
created rough estimates for four major categories of mammals: humans, domesticated animals, and those that were found in wild terrestrial and marine environments. A further breakdown of mammal groups are found within each category.
To achieve this, they took the estimated number of species from census data and multiplied it with each species’ average body mass.
One component worth pointing out is that animals contribute very different amounts to the world’s biomass total. For example, whales significantly outweigh rodents in terms of biomass, even though there are fewer species and populations of whales. The fact that whales are so much larger than rodents means that even smaller populations can contribute a meaningful portion to overall biomass.
Mammalian Biomass, Organized Neatly
Each larger cube above represents 20 million metric tons of carbon, and the entirety of the visualization represents all living mammalian life on Earth.
The paper separates mammals into four distinct categories:
Category | Total Mass (Mt) | Top Sub-Category |
---|---|---|
Domesticated Mammals | 651 | Cattle (416 Mt) |
Humans | 394 | n/a |
Wild Marine Mammals | 40 | Baleen Whales (23 Mt) |
Wild Terrestrial Mammals | 24 | Even-Hoofed Mammals (11 Mt) |
Total | 1,109 |
One of the most obvious takeaways from this data is that humans make up one-third of total mammalian biomass.
Perhaps even more strikingly, the animals we’ve domesticated for food, companionship, and labor make up close to 60% of the total weight of Earth’s mammals. Domesticated dogs and cats alone equal the total weight of all other wild land mammals combined.
The world’s sheep, on their own, weigh as much as all the whales and seals in the ocean. Domesticated buffalo such as the water buffalo, a species commonly found in Asia, combine to have the third largest biomass of all mammals.
Finally, there’s one category of mammal that comes way out on top.
Cattle Planet
The global livestock population has risen along with the human population, and cattle are now the top mammal in the world by weight.
In fact, just the United States’ share of cattle matches the biomass of all wild mammals on Earth.
As the standard of living continues to rise for people around the world, beef consumption has been increasing in many developing countries. Of course, raising cattle is a resource and land intensive operation, and there have been very real impacts on a global scale. For one, cows are a major source of methane emissions. As well, in Brazil, which accounts for around 25% of the world’s cattle population, pasture has directly replaced large swaths of rainforest habitat.
Waning Wildlife
At the very bottom of the visualization, dwarfed by humans and domesticated mammals, lies the vast array of wild mammals that live on planet Earth.
It’s sobering to see that the biomass of North America’s human population alone compares closely with that of all terrestrial wild mammals in the world. This includes plentiful creatures like rats and mice, as well as large mammals like elephants and bears.
Below are the top 10 wild mammalian contributors to biomass in the natural world.
Rank | Contributor | Total Mass (Mt) | Individuals (millions) |
---|---|---|---|
#1 | Fin Whales | 8 | 0.1 |
#2 | Sperm Whales | 7 | 0.4 |
#3 | Humpback Whales | 4 | 0.1 |
#4T | Antarctic Minke Whales | 3 | 0.5 |
#4T | Blue Whales | 3 | 0.05 |
#6 | White-Tailed Deer | 2.7 | 45 |
#7 | Crabeater Seals | 2.0 | 10 |
#8 | Wild Boar | 1.9 | 30 |
#9T | African Elephants | 1.3 | 0.5 |
#9T | Bryde's Whales | 1.3 | 0.1 |
In the ocean, whales and seals are the heavyweight champions. On land, deer, and boar come out on top as they are both heavy and plentiful.
Humans have a complicated relationship with large mammals. We feel a very clear connection to these creatures, and they are often the key figures in conservation efforts. That said, even small populations of humans have wiped out large mammal species in the past.
The news that cattle outweigh wild land animals by a factor of 20:1 is a reminder that human influence is perhaps even more powerful than we think.
The more we’re exposed to nature’s full splendor […] the more we might be tempted to imagine that nature is an endless and inexhaustible resource. In reality, the weight of all remaining wild land mammals is less than 10% of humanity’s combined weight. – Ron Milo, Professor of Systems Biology
Source: The global biomass of wild mammals
Data notes: To come up with the numbers above, scientists estimated the total biomass of wild mammals on Earth by manually collecting population estimates for 392 land mammal species, which make up about 6% of all wild land mammal species, and using machine learning to infer the global populations of the remaining 94%. Their estimate includes 4,805 wild land mammal species out of approximately 6,400 known and extant wild land mammal species, excluding low-abundance species for which data are scarce.
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