Does anyone know the length of the longest radio wave?

A search lead to quora

What’s the longest possible wavelength/lowest possible frequency/lowest possible energy of electromagnetic radiation?
https://www.quora.com/Whats-the-longest-possible-wavelength-lowest-possible-frequency-lowest-possible-energy-of-electromagnetic-radiation

The electromagnetic spectrum covers electromagnetic waves with frequencies ranging from below one hertz to above 10^25 hertz, corresponding to wavelengths from thousands of kilometers down to a fraction of the size of an atomic nucleus.

Doesn’t give the exact number though.

Tau.Neutrino said:

Does anyone know the length of the longest radio wave?

A search lead to quora

What’s the longest possible wavelength/lowest possible frequency/lowest possible energy of electromagnetic radiation?
https://www.quora.com/Whats-the-longest-possible-wavelength-lowest-possible-frequency-lowest-possible-energy-of-electromagnetic-radiation

The electromagnetic spectrum covers electromagnetic waves with frequencies ranging from below one hertz to above 10^25 hertz, corresponding to wavelengths from thousands of kilometers down to a fraction of the size of an atomic nucleus.

Doesn’t give the exact number though.

I suspect you’re chasing fairies. There’s really no correct answer.

A frequency of 0.000000000000001 Hz is going to have a really long waveform but a frequency of 0.0000000000000001 Hz is going to have one that is ten times longer.

Repeat ad infinitum :)

i suppose we could argue that a radio wave that is much much larger than the diameter of the Hubble volume (about 30 billion light years) might as well not exist.

dv said:

i suppose we could argue that a radio wave that is much much larger than the diameter of the Hubble volume (about 30 billion light years) might as well not exist.

It’s not up to us.

Bubblecar said:

dv said:

i suppose we could argue that a radio wave that is much much larger than the diameter of the Hubble volume (about 30 billion light years) might as well not exist.

It’s not up to us.

Seems defeatist

Tau.Neutrino said:

Does anyone know the length of the longest radio wave?

A search lead to quora

What’s the longest possible wavelength/lowest possible frequency/lowest possible energy of electromagnetic radiation?
https://www.quora.com/Whats-the-longest-possible-wavelength-lowest-possible-frequency-lowest-possible-energy-of-electromagnetic-radiation

The electromagnetic spectrum covers electromagnetic waves with frequencies ranging from below one hertz to above 10^25 hertz, corresponding to wavelengths from thousands of kilometers down to a fraction of the size of an atomic nucleus.

Doesn’t give the exact number though.

I do know the precise length of the longest electromagnetic wave. I did a private research project on the topic and have a Good Scientist Cartoon about it. Wait until tomorrow and I’ll find it for you.

dv said:

i suppose we could argue that a radio wave that is much much larger than the diameter of the Hubble volume (about 30 billion light years) might as well not exist.

gunna need a lot of wire for the antenna.

Boris said:

dv said:

i suppose we could argue that a radio wave that is much much larger than the diameter of the Hubble volume (about 30 billion light years) might as well not exist.

gunna need a lot of wire for the antenna.

And the bit rate may be a tad low.

sibeen said:

Boris said:

dv said:

i suppose we could argue that a radio wave that is much much larger than the diameter of the Hubble volume (about 30 billion light years) might as well not exist.

gunna need a lot of wire for the antenna.

And the bit rate may be a tad low.

yeah, Project Sanguine.

Suppose there is a longest wave, produced by some source. If the source moves away, Doppler effect says that the wave “stretches”, or becomes longer. This makes it longer than the longest wave.

btm said:

Suppose there is a longest wave, produced by some source. If the source moves away, Doppler effect says that the wave “stretches”, or becomes longer. This makes it longer than the longest wave.

But hold on, if it moves towards you the longest wave is now no longer the longest wave.

sibeen said:

btm said:

Suppose there is a longest wave, produced by some source. If the source moves away, Doppler effect says that the wave “stretches”, or becomes longer. This makes it longer than the longest wave.

But hold on, if it moves towards you the longest wave is now no longer the longest wave.

is it shorter than the Last Wave?

sibeen said:

btm said:

Suppose there is a longest wave, produced by some source. If the source moves away, Doppler effect says that the wave “stretches”, or becomes longer. This makes it longer than the longest wave.

But hold on, if it moves towards you the longest wave is now no longer the longest wave.

Yes. That’s the same argument I’ve used to show there’s no shortest wavelength.

I think if we stuck with a wavelength as generated by the transmitter we would have a better chance of having a coherent answer.

:-)

certainly down to the millihertz range, which could be ~.001^ HZ, if what I just got from the the online calculator is right that’s a wavelength of 299792458000 metres?

you might want to search_ micropulsations_

sibeen said:

Boris said:

dv said:

i suppose we could argue that a radio wave that is much much larger than the diameter of the Hubble volume (about 30 billion light years) might as well not exist.

gunna need a lot of wire for the antenna.

And the bit rate may be a tad low.

Up front, I want to say a few things:

• a wave may be sinusoidal and of constant period like ripples on a pond or it can be non-sinusoidal and of varying period, like ocean waves. ie. electromagnetic waves aren’t always sinusoidal of constant period.
• below a certain period, electromagnetic waves tend to be called “geomagnetic variations” rather than “electromagnetic”. The main reason for that is because antennas for low frequency waves measure the magnetic field (loop antenna) rather than the electric field (dipole antenna). A loop antenna doesn’t have to have a long length of wire to be effective at low frequencies.

Here’s the answer. I’ve expressed it as period rather than wavelength.
Wavelength = speed of light * period = speed of light / frequency

Here’s a quick table of period range vs source of electromagnetic waves.
Here we go. Period range (s) vs source for long trequency electromagnetic waves.

Period range (s), Source

3e-5 to 3e-4, Very Low Frequency (VLF)
3e-4 to 3e-3, Ultra-Low Frequency (ULF)
3e-3 to 0.03, Super-Low Frequency (SLF)
0.03 to 0.3, Extremely Low Frequency (ELF)
0.015 to 0.3, Schumann Resonance in Ionosphere. (wikipedia)
10 to 200, Compressive pulsations in magnetosphere (Pc4-5)
70 to 500, Kelvin-Helmholtz Waves in the magnetosphere
84 to 430, Kelvin-Helmholtz Waves in Jupiter’s magnetosphere
500 to 1200, Solar surface convection
600 to 4000, Solar flares
2e6, Solar Rotation
1.5e7 to 4e7, Annual and semi-annual Geomagnetic Variations
6e8 to 8e8, Solar Sunspot Cycle 18yr to 28yr
3e12, Cryptochrons of Geomagnetic Variation (100000 years), ie. we haven’t the foggiest idea what causes these
Geomangetic reversals (200000 to 1.5 million years)
230 million years,Sun’s Orbit around Milky Way

So the length of the longest electromagnetic wave is 230 million light years.

And as a chart.

Here’s another version of the same chart.

Boris said:

I think if we stuck with a wavelength as generated by the transmitter we would have a better chance of having a coherent answer.

:-)

Seems to make sense to me.

https://dd5lp.com/antennas/40-metre-horizontal-loop-antenna/

you need quite a bit of wire.

Nice diagram for gravitational waves here.

The Rev Dodgson said:

Nice diagram for gravitational waves here.

And not to forget TATE on gravitational waves

mollwollfumble said:

sibeen said:

Boris said:

gunna need a lot of wire for the antenna.

And the bit rate may be a tad low.

Up front, I want to say a few things:

• a wave may be sinusoidal and of constant period like ripples on a pond or it can be non-sinusoidal and of varying period, like ocean waves. ie. electromagnetic waves aren’t always sinusoidal of constant period.
• below a certain period, electromagnetic waves tend to be called “geomagnetic variations” rather than “electromagnetic”. The main reason for that is because antennas for low frequency waves measure the magnetic field (loop antenna) rather than the electric field (dipole antenna). A loop antenna doesn’t have to have a long length of wire to be effective at low frequencies.

Here’s the answer. I’ve expressed it as period rather than wavelength.
Wavelength = speed of light * period = speed of light / frequency

Here’s a quick table of period range vs source of electromagnetic waves.
Here we go. Period range (s) vs source for long trequency electromagnetic waves.

Period range (s), Source

3e-5 to 3e-4, Very Low Frequency (VLF)
3e-4 to 3e-3, Ultra-Low Frequency (ULF)
3e-3 to 0.03, Super-Low Frequency (SLF)
0.03 to 0.3, Extremely Low Frequency (ELF)
0.015 to 0.3, Schumann Resonance in Ionosphere. (wikipedia)
10 to 200, Compressive pulsations in magnetosphere (Pc4-5)
70 to 500, Kelvin-Helmholtz Waves in the magnetosphere
84 to 430, Kelvin-Helmholtz Waves in Jupiter’s magnetosphere
500 to 1200, Solar surface convection
600 to 4000, Solar flares
2e6, Solar Rotation
1.5e7 to 4e7, Annual and semi-annual Geomagnetic Variations
6e8 to 8e8, Solar Sunspot Cycle 18yr to 28yr
3e12, Cryptochrons of Geomagnetic Variation (100000 years), ie. we haven’t the foggiest idea what causes these
Geomangetic reversals (200000 to 1.5 million years)
230 million years,Sun’s Orbit around Milky Way

So the length of the longest electromagnetic wave is 230 million light years.

And as a chart.

Here’s another version of the same chart.

> 0.03 to 0.3, Extremely Low Frequency (ELF)

Used for submarine communications.