Once an ancient tourist destination, Plutonium cave, also known by the nickname “hell’s door”, hides a secret that only after 2,000 years, modern scientists can explain.
Two thousand years ago, ancient travelers arrived at a Greco-Roman temple at Hierapolis (modern-day Turkey), located above a cave believed to be a portal to the afterlife. Their purpose is simple: watch animals, from birds to cows, collapse in front of the cave. This cave called “Plutonium” – named after the Greek god of hell Pluto – is said to be able to spit out “the breath of death” , taking the life of any creature that dares to come near, except for the high priests. They are the ones who are immune to the “breath of death” and are responsible for bringing the animals into the cave to sacrifice.
Natural historian Pliny “The Elder” describes this phenomenon as the ” gate of Charon “ – the ferryman who carried the souls of the dead across the Styx and Acheron rivers to the underworld in Greek mythology.
The entrance to the Plutonium cave.
However, today, scientists have lifted the mythological curtain behind this seemingly supernatural phenomenon. According to a study published in the journal Archeology and Anthropology this past February, a fissure in the earth’s surface, deep inside the cave, has been producing CO2 at “deadly ” concentrations . Specifically, with a portable gas analyzer, Mr. Hardy Pfanz and a team of volcanologists found CO 2 with a concentration of 4-53% at the mouth of the cave and the highest at 91% inside. This concentration is more than enough to kill all living things.
“Mammalian species (including humans) can start to have problems at less than 5% CO 2 ,” Pfanz told CNN. “At 7%, the longer we stay, the more severe the symptoms like sweating, dizziness, increased heart rate. Even higher concentrations lead to suffocation due to lack of oxygen as well as blood, brain cells… being acidified.”
Therefore, all animals that enter the cave quickly collapse. Pfanz revealed that, during the research, the team found the carcasses of several birds, mice and more than 70 beetles.
During the day, this gas is scattered by sunlight. The cave becomes most dangerous at dawn, the volcanic gas that accumulates overnight enough to kill all living things nearby.
At dawn, carbon dioxide concentrations reach 50% at the bottom of the lake in the cave, up to 35% at 10 cm but begin to decline rapidly at 40 cm and above. This elevation accumulation also explains the ghostly recorded event, that when the Roman priests led the ox near this “gate of hell” , the ox died but the man was fine: simple Simply put, a person standing upright is much taller than an animal, thus avoiding the release of toxic gases.
Like in the past, today, Plutonium still attracts thousands of visitors each year. Italian archaeologist Franceso D’Andria – who rediscovered the cave in 2013 – said he and his colleagues also found evidence of a stage once erected around Plutonium to serve the Ancient travelers.
The ancient Greek geographer Strabo once described: “ Any animal that goes inside will face instant death . The bulls that were led inside all collapsed and were dragged outside. I threw in a few sparrows and they immediately fell,” he wrote.
The graphic simulates the buildings surrounding Plutonium, including the seats for the audience.
Strabo realized this reaction was related to the gas – “space is full of smoke, so dense that the ground cannot be clearly seen” – but does not understand why the gas affects the animals but the monks and did not bother. He said that they may be protected by gods or simply monks who held their breath when entering the cave.
However, Mr. Pfanz’s research has also revealed the mystery behind this: the monks and the animals are of different heights ! It is known that CO 2 is heavier than oxygen, so it will sink to the bottom, forming a toxic “gas lake” on the ground. Therefore, the animals will “have enough” and the monks will be safe.
“The noses of the animals were right in the middle of the lake of poison gas,” Pfanz said.
In addition, Mr. Pfanz said that the monks knew well about the origin of the “breath of death” as well as the change in gas concentrations at different times of the day. Research results also show that CO2 concentration is quite high at dawn and dusk because the gas is dispersed by sunlight. However, archaeologist D’Andria disagrees with this view. He said that, based on finding many oil lamps at the cave entrance, “it is very likely that many religious activities were carried out at night”.
Thus, the “gate to hell” is actually a hiding place for a rather dangerous scientific phenomenon. However, the ancient city of Hierapolis still becomes one of the attractions that attract thousands of tourists not only because of the Plutonium cave but also because it has hot springs. If you have the opportunity to visit this place, remember to pay attention to safety!