Does the Earth's magnetic field make life here possible?

Someone told me that the Earth’s magnetic field stops the charged particles from the solar wind. If the magnetic field was not there, the solar wind would fry us all. Is this true? Or is it somewhat of an oversimplification?

I’m sure there will be plenty of expert 'dopers on to discuss this any second, but my understanding is without the magnetic field the solar winds would strip the planet of a lot of it’s atmosphere and liquid water, as well as the problem you asked about (i.e. the radiation that would get through that is currently being partially diverted by the magnetic field). Which means the answer is ‘yes’…without the earth’s magnetic field, higher life forms (and even lower life forms for all I know) would ultimately be screwed.

In the short term it would also screw up our telecommunications systems and destroy much of our technical infrastructure…again, at least that’s my understanding based on some of the emergency planning for high level solar activity I’ve seen.

-XT

Mars is massive enough and cool enough that it should be able to support a much thicker atmosphere, comparable to our own (and yes, that also means that ours is thinner than it could be, too). Last I heard, the best hypothesis as to why it’s as thin as it is is its very weak magnetic field, that the solar wind did indeed blow most of the atmosphere away. That’s a slow process, though: Even if Earth’s magnetic field were to somehow disappear permanently, we’d probably still be OK for tens or hundreds of millions of years.

The Solar Wind at Mars

Solar Wind Rips Up Martian Atmosphere

On the flip side, one could argue that if Earth had never had its magnetic field, we could imagine life evolving to be more resistant to radiation.

Yes, it’s possible it may affect biological life in a negative way. When the magnetic field collapses during the next geomagnetic reversal it will certainly change how much energy moves through the atmosphere.