Why do we need electromagnetic waves?

  • #1
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Main Question or Discussion Point

(Sorry for my poor english.) I'm just wondering why is it necessary to have oscillating EM fields for life existing on Earth. The sun has a magnetic field (I think a static one), so why it's not enough to life exists? Also, why we and other animals only see the objects if the fields are oscillating?
 

Answers and Replies

  • #2
marcusl
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You have taken a very anthropomorphic posture--as though life is the important thing while physical nature and laws are secondary. In our universe, there are electromagnetic fields. That's the starting point. Life was able to evolve, partly as a result. We see visible light because a) it is energetic enough to cause chemical changes, which organisms can exploit, b) because the wavelengths are small enough that we can build an antenna with gain (lens) that is a reasonable size relative to our bodies, and c) because our sun puts out copious energy in that range (and our atmosphere allows it to reach the surface).
 
  • #3
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The sun has a magnetic field (I think a static one), so why it's not enough to life exists?
Static EM fields can't transport energy across a vacuum.

But I agree with marcusl that the question is kind of backwards, like life causes EM.
 
  • #4
sophiecentaur
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(Sorry for my poor english.) I'm just wondering why is it necessary to have oscillating EM fields for life existing on Earth. The sun has a magnetic field (I think a static one), so why it's not enough to life exists? Also, why we and other animals only see the objects if the fields are oscillating?
Light is only a very small portion of the whole spectrum of EM waves. It spans from the very lowest frequency of electrical oscillations (50Hz mains electricity) up to the highest energy Gamma Rays 1019Hz. They all involve time varying E and H fields.
 

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