Why do we need electromagnetic waves?

  • #1
931
56
(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
Science Advisor
Gold Member
2,762
412
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).
 
  • Like
Likes davenn and Drakkith
  • #3
Dale
Mentor
Insights Author
2020 Award
31,102
7,785
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
Science Advisor
Gold Member
2020 Award
25,691
5,126
(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.
 

Related Threads on Why do we need electromagnetic waves?

Replies
31
Views
3K
Replies
2
Views
1K
  • Last Post
Replies
1
Views
1K
  • Last Post
Replies
2
Views
2K
  • Last Post
2
Replies
37
Views
6K
  • Last Post
Replies
0
Views
1K
Replies
5
Views
1K
Replies
7
Views
2K
Replies
25
Views
18K
  • Last Post
Replies
12
Views
3K
Top