These sulfur gas particles reflect incoming solar radiation and have a strong cooling effect. What did life on Earth look like at the time, and how did it change as a consequence of these events? There were certainly bacteria and there were also algae and unicellular primitive animals, or protists.
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There is also evidence that the first multicellular animals originated at this time, probably something like sponges. Why is a matter of speculation: There are a number of ideas on this, but they are difficult to test. One idea is that on Snowball Earth, ecosystems may have been more isolated from one another and this might be a situation that would be helpful for evolving new forms of life, and particularly forms of life that are altruistic — ones with cells that find that there is an advantage in working together rather than working individually.
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So more isolation of different ecosystems might have allowed certain ecosystems that had a higher proportion of these multicellular altruists to establish a foothold. I think I underestimated how emotional people would get about it and how wedded people were to the idea that the Earth has never really been greatly different than it is today. That was as hard for a 19th-century geologist to accept as Snowball Earth has been for 20th-century geologists.
It was sort of embarrassing. But between and that situation dramatically changed. Alternative theories have arisen over the years, including what is called the Slushball theory — a less extreme version of Snowball Earth. How does pinning down the dates help sort out these alternative theories? In the Slushball scenario, carbon dioxide would start building up very quickly, so the glaciation would be short-lived and the ice would retreat gradually.
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This is not what we see in the geologic record. We now know that the first Snowball lasted for 58 million years and that is completely inconsistent with the Slushball idea. Also, we see the Snowball glaciations terminate extremely abruptly and they are followed by clear evidence of a complete and abrupt climate reversal, a very hot period. That is not explained by the Slushball model. Paul Hoffman has spent a cumulative 50 months collecting evidence of Snowball Earth in the desert mountain ranges of Namibia.
The dating has created a new set of problems. One thing the dating revealed was that the two Snowball Earths occurred in rapid succession and were very unequal in duration. And why was it that there was just this short interval between the two?
So why two in rapid succession? These are new questions that have arisen as a result of our understanding of the timing. The future is a long time. I think we can say it is not going to happen in the next several tens of thousands of years. The history of our planet is one of the greatest stories. Because we live here and we are dependent on this place, I think it is very important to understand that the Earth has not always been the way it is today.
Laura Poppick is a freelance science journalist in Portland, Maine — a place that sometimes feels like a large snowball.
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Prior to her career in journalism, she worked in a laboratory at Princeton University studying Snowball Earth rocks. Twitter: laurapoppick. Your generosity will help us continue making scientific knowledge accessible to all. Geologist Paul Hoffman has studied the Snowball Earth theory for 25 years.
He discusses how this theory evolved over his career and some of the key milestones that have helped it become more widely accepted among geologists today. About million years ago, an explosion of life expanded across the planet and gave rise to the major animal groups alive today.
Fossils help researchers explore scenarios that could have instigated this unique episode in Earth history. Close Topics. Submit Cancel. Search Menu. Physical World. A something woman approaches the stage. Few are able to explain why a conspiracy might exist, why scientists might go to such great lengths to create false evidence.
Earth, Mars, And 'Swapping Spit' Theory
Around people have paid to attend. Behind me, two men in their 20s are scrolling through images of the Earth taken from space. Every once in a while they land on a photograph that piques their interest, enter into a brief discussion, and move on. A middle-aged man a couple of seats away leans in to ask the pair what they are doing. Around the room, there is general consensus that Nasa is in the habit of doctoring its imagery, and the agency is considered untrustworthy. For long-standing Flat Earthers, the information is old-hat.
But the young men have yet to fully commit to the community. Soon, the three of them are deep in conversation. The older man introduces his take on the Nasa cover-up. That the colour of the ocean in one image is different to the colour of the ocean in another; that in two pictures the continents seem to be in the same position, but in a third they appear to have shifted.
The images are riddled with discrepancies, he says.
Is the Earth flat? Meet the people questioning science | Global | The Guardian
In each, a presenter denounced conventional science as flawed, if not entirely fabricated, and offered alternative hypotheses. When the community was still very young, around , theories spread quickly, though only between outlying networks of conspiracy theorists. Now hypotheses appear weekly, released across hundreds of online channels.
Many come from the US, where the scene simmers not far below the mainstream. Conventions are popping up throughout North America. In August, believers will travel to Edmonton, Canada. It will set sail some time in The American community is big and brash and filled with personalities vying for public influence. There, Flat Earthers have secured airtime on almost every major television network, sometimes primetime slots, and the movement has been lent credibility by celebrity support.
The rapper BoB is a believer. But, because Flat Earth has been a YouTube phenomenon, the same hypotheses tend to appear everywhere: that the Earth is flat and round, like a pancake. That it is surrounded on all sides by the Antarctic, a huge impassable wall of ice, and protected by a dome. That it is not hurtling through space at great speed but rooted somehow, an immovable mass: still, calm, glorious, the epicentre of the universe. This is contrary to thousands of years of science, of course. Aristotle claimed the world was a sphere some time around BC. Plato agreed.
It was confirmed in the s when a Spanish expedition led by Magellan circumnavigated the globe. Most of us have believed ever since, though not all, apparently.
Apparently, Some People Believe the Earth Is Shaped Like a Donut
Those at the beginning of their Flat Earth journey typically encounter hundreds of ideas — some alike, some wildly contradictory — in a very short space of time. Sometimes that takes three months. For many it takes at least six. A woman at the convention tells me she has so far logged 8, hours of research, though others consider that extreme. Often research is conducted alone, at a computer screen.
The convention is meant to remedy this. The comment has multiple meanings. Many in the audience have only ever experienced the community online. The speakers, who walk around the hotel with an air of minor celebrity, are regularly referred to by their YouTube handles. Every now and then a group might meet informally in a pub, but often the turn-out is tiny.