Why do we need electromagnetic waves?

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Discussion Overview

The discussion revolves around the necessity of oscillating electromagnetic (EM) fields for the existence of life on Earth. Participants explore the role of electromagnetic waves, particularly in relation to visible light and the sun's magnetic field, questioning why static fields alone are insufficient for life and perception.

Discussion Character

  • Exploratory
  • Conceptual clarification
  • Debate/contested

Main Points Raised

  • One participant questions the necessity of oscillating EM fields for life, suggesting that the sun's static magnetic field should suffice.
  • Another participant argues that life evolved partly due to the presence of electromagnetic fields, emphasizing the importance of visible light's energy and wavelength for biological processes.
  • A participant points out that static EM fields cannot transport energy across a vacuum, implying that oscillation is crucial for energy transfer.
  • It is noted that light is only a small part of the EM spectrum, which includes a wide range of frequencies, all involving time-varying electric and magnetic fields.

Areas of Agreement / Disagreement

Participants express differing views on the relationship between EM fields and the existence of life, with some suggesting that life influences EM phenomena while others argue the opposite. The discussion remains unresolved regarding the necessity of oscillating fields versus static fields.

Contextual Notes

There are assumptions regarding the definitions of static and oscillating fields, as well as the implications of energy transport in relation to life processes that are not fully explored.

kent davidge
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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?
 
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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).
 
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kent davidge said:
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.
 
kent davidge said:
(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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