In 2023, scientists in various fields continue to write those fascinating stories for us. From the oldest black holes to the heaviest animals to the oldest riders, let's take a look back at some of the most amazing discoveries:
The oldest black hole
(图/Chandra & JWST)
In the 13.8 billion years of the universe's history, galaxies have evolved since their inception. Today we know that in almost all galaxy centers, there is a supermassive black hole hidden – hundreds of thousands, if not billions of times, the mass of the Sun.
This year, astronomers discovered the most distant and oldest supermassive black hole ever observed at the center of galaxy UHZ1. The black hole is 13.2 billion light-years away from Earth, dating back only 470 million years after the Big Bang. This discovery will help astronomers reveal exactly how the first supermassive black holes in the universe formed.
The most distant stars
(图/NASA, ESA, CSA, D. Coe,B. Welch,Z. Levay)
Earendel, the most distant star ever discovered by the Hubble Space Telescope. It took 12.9 billion years for the light it emitted to reach our sight, which means that the star shone within the first billion years of the universe's formation. Since the universe is expanding all the time, this star is not simply 12.9 billion light-years away, but 28 billion light-years away!
This year, initial observations of Elendil by the Webb Space Telescope showed that the star is a massive B-type star that is more than twice as hot and about 1 million times brighter than the Sun.
The most distant fast radio bursts
(图/ESO/M. KORNMESSER)
Fast radio bursts (FRBs) are powerful radio pulses that are very short-lived, only between milliseconds. Since the FRB was first detected in 2007, astronomers have continued to capture these intense radio wave bursts, most of which come from galaxies quite far away. Although a lot of FRB events have been captured, many of the puzzles associated with it are still waiting to be solved.
This year, astronomers discovered the most distant FRB to date. The event, named FRB 20220610A, has traveled through the universe for about 8 billion years before it was captured by telescopes on Earth.
The heaviest animal
(图/Alberto Gennari)
The Colossus Peruvian whale (Perucetus colossus) is a species of cetacean. This long-lost ancient whale dates back about 39 million years.
Scientists excavated 18 bones of a colossus Peruvian whale in the Peruvian desert, including 13 vertebrae, four ribs and part of the hip bone of the right hip. These bones are all very large, much larger than those of all other whales of the same period. Calculations have shown that the total weight of the Colossus Peruvian whale may be between 85~340 tons. If this cap is correct, then the Colossus Peruvian whale will be the heaviest animal ever recorded.
The oldest wooden structure
(Photo/Nature)
When did humans first start building wooden buildings? The answer is earlier than previously thought. This year, scientists excavated well-preserved wood at the archaeological site of Kalambo Falls in Zambia that dates back at least 476,000 years — which predates the evolution of our Homo sapiens.
By analyzing the stone cuts on the wood, the researchers believe that these large logs, which have been transformed, may be the foundation of the platform or part of a dwelling. This is the world's earliest evidence that people deliberately put logs together. Timber is rarely found in such an ancient site as they usually decay and disappear, but at Kalambo Falls, the high water level allows the timber to be preserved permanently.
The oldest footprint
（图/Charles Helm）
More than 20 years ago, footprints left by human ancestors more than 50,000 years ago are very rare. At that time, there were only four archaeological sites in the whole of Africa where traces of ancient humans existed. Today, more than 20 years later, the situation is very different. In Africa, there are as many as 14 ancient human sites dating back more than 50,000 years, of which 5 are located in East Africa and 9 are concentrated in South Africa.
In 2023, scientists discovered the oldest footprint belonging to Homo sapiens to date by dating seven ancient human sites in a South African heritage complex. These ancient traces span a wide range of years: the most recent date back to about 71,000 years ago, and the oldest to 153,000 years ago.
The oldest rider
(图/Michał Podsiadło)
The use of horses as a means of transportation was a defining event in the development of human culture, marking a key turning point in human history. Previously, since riding a horse did not necessarily have to be a signature piece of equipment, most of the archaeological research focused on the horse itself, rather than the rider.
In 2023, after a meticulous survey of a large number of archaeological sites, archaeologists developed a set of "horseback riding syndrome": it uses six characteristics of human bones as indicators of horseback riding activity, which is used to determine whether people in prehistoric mounds may have ridden horses in the past. In a burial mound in Hungary dating from about 4300 BC, the owner of four of the six riding features is revealed, probably the oldest rider ever found.
The most accurate timer
(Photo/CERN)
The atomic clock is currently the most accurate timekeeper in the world, and it uses the energy transition of electrons to keep time. Just like the electrons in the atom, the protons and neutrons in the nucleus also occupy discrete energy levels, so the nucleus has a similar transition. This transition promises to lead to a more accurate type of clock than an atomic clock – a nuclear clock. However, building a nuclear clock is a very difficult task, because it is extremely difficult to observe such nuclear transitions and accurately know the energy difference of the energy levels.
One of the characteristics of a nuclear transition is the emission of a photon, and by measuring this photon, the energy of the nuclear transition can be accurately measured. This year, physicists finally detected the photons emitted by the transition by changing the probability of photons emitted by thorium-229, taking a crucial step in the development of nuclear clocks.
The hottest state of matter
(Photo/STAR)
Quarks and gluons are elementary particles in the universe, and they are tightly bound together under the action of force, one of the fundamental forces in nature, to form complex particles such as protons and neutrons. The only way to separate these composite particles is to create some of the hottest states of matter in the lab, the quark gluon plasma (QGP).
In modern physics, physicists must use special devices, such as the Relativistic Heavy Ion Collider (RHIC), to study QGP. During the experiment, detecting a particle called (upsilon) is the ideal particle to determine whether a collision produces a QGP. This year, for the first time, scientists measured the inhibition of three particles on the RHIC and discovered the expected pattern.
Mammals that sleep the least
（图/Brocken Inaglory /wikimedia commons）
Northern elephant seals are some of the best divers in the world, and they spend most of their time at sea. For years, scientists have puzzled how northern elephant seals, which spend long hours foraging at sea, get enough sleep. Because unlike cetaceans and "eared" seals, such as sea lions, walruses cannot sleep in a single hemisphere, meaning that one half of the brain rests and the other half remains alert.
In 2023, scientists recorded the brain activity of northern elephant seals for the first time and found that northern elephant seals only sleep an average of less than 2 hours a day at sea. Unlike other marine mammals, they enter full REM sleep, showing sleep paralysis. And they will dive into the ocean at a depth of about 300 meters to sleep, a position below the depth occupied by their predators.
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