The discussion centers on identifying scientifically plausible cosmic events that could lead to the total annihilation of Earth, with a focus on scenarios that allow for a four-year warning period. Participants suggest various events, including the potential for a medium to large black hole, supernovae, and the interaction of multiple stars in a cluster. While supernovae may not completely destroy Earth, they could sterilize it, and the idea of a black hole or a hypervelocity planet collision presents a more definitive threat. The consensus emphasizes the difficulty of achieving total destruction, with many scenarios leaning towards significant biosphere damage rather than complete obliteration.
PREREQUISITESWriters, astrophysicists, and science fiction enthusiasts interested in plausible cosmic disaster scenarios and their scientific underpinnings.
This matches with my request to provide references. So where are the sources for your claims?brenan said:Really - you should read up - its fascinating work
I'm afraid your posts about magnetic flips and pottery is misinformation.brenan said:magnetic anomoly in pottery is how the field flip was discovered. Really - you should read up - its fascinating work. I wrote about it when the discovery was announced. I'm guessing the year but I think it would have been about 1990 or perhapsa little earlier - I'd need to check my records.
Evidence of that decline has come from a surprising source. People have been making pottery for thousands of years. Archaeologists study pots to learn about ancient cultures. But these vessels have another story to tell.
JOHN SHAW: Pottery acts just like a magnetic tape recorder. It records the Earth's magnetic field when the pottery is first made.
NARRATOR: An ancient pot is a magnetic time capsule. John Shaw has learned how to extract from it a precise measurement of the strength of the magnetic field as it was in antiquity.
Like volcanic rock, clay contains tiny pieces of an iron-based mineral called magnetite. At the microscopic level, magnetite contains lots of distinct magnetic regions, in effect, tiny magnets. But in raw clay, these microscopic magnets all point in different directions, so they fail to create an overall magnetic field. That means a lump of clay on the potter's wheel is not, itself, magnetic. Not yet, anyway.
JOHN SHAW: Now the interesting part is when the pot's fired.
NARRATOR: The intense heat in the kiln erases all the magnetic regions. But as the pot begins to cool, new magnetic regions form in the magnetite. And as the regions reform, they align with the Earth's magnetic field, just like compass needles. With millions of tiny magnets all pointing in the same general direction, the pot itself becomes slightly magnetic. Once it has cooled, the magnetism is locked in.
JOHN SHAW: So if we take an ancient pot like this one, which is from Peru, when it cooled for the first time, it cooled in the Earth's ancient magnetic field and it became magnetized in that field. And of course, if the field's very strong, then the pot's strongly magnetized, and if the field's very weak, then the pot's weakly magnetized.
More misinformation.brenan said:Right now the Earth's magnetic field is about due to flip. Most scientists seem to be ignoring this.
All these questions remain unanswered, though experts like Dennis Kent, the Rutgers University geologist who supplied NOVA with updated figures for the time line, are hard at work trying to answer them. In the meantime, not to worry. Reversals happen on average only about once every 250,000 years, and they take hundreds if not thousands of years to complete.
Even the weakening currently under way may be a false alarm. The field often gets very weak, then bounces back, never having flipped. As Ron Merrill, a magnetic-field specialist at the University of Washington remarked when asked whether we're in for a reversal: "Ask me in 10,000 years, I'll give you a better answer." So hang on to your compass. For the foreseeable future, it should work as advertised.