# Naked Science Forum

## On the Lighter Side => New Theories => Topic started by: Black hole on 15/10/2021 21:03:17

Title: Does light of different wavelengths have the same energy?
Post by: Black hole on 15/10/2021 21:03:17
Mark wants to know:

Since the Universe is expanding and light stretches across it as it does so becoming more red, what happens to the lost energy when the shorter wavelength, higher energy light towards the blue end of the spectrum is shifted into lower energy red wavelengths?

There is no lost energy t   high frequency photon energy divided by volume over time at c . 450nm has the same energy has 750nm but it is divided by a greater volume. In linear terms = in regards to the energy amount .
Title: Re: Does light of different wavelengths have the same energy?
Post by: Kryptid on 15/10/2021 21:20:20
450nm has the same energy has 750nm

No, it doesn't. A photon with a wavelength of 450 nanometers has (750 nm/450 nm = ~1.67) times as much energy as a photon with a wavelength of 750 nanometers.
Title: Re: Does light of different wavelengths have the same energy?
Post by: Black hole on 15/10/2021 21:48:16
450nm has the same energy has 750nm

No, it doesn't. A photon with a wavelength of 450 nanometers has (750 nm/450 nm = ~1.67) times as much energy as a photon with a wavelength of 750 nanometers.

Something else you misunderstood in physics class I assume ?

Have you ever stretched an elastic band ?

E=

E=

Do you see that although 1 is stretched that the energy of stays the same ?

You're not considering the summation !

Title: Re: Does light of different wavelengths have the same energy?
Post by: Kryptid on 15/10/2021 21:53:02
Have you ever stretched an elastic band ?

Photons are not elastic bands.
Title: Re: Does light of different wavelengths have the same energy?
Post by: Black hole on 15/10/2021 23:59:59
Have you ever stretched an elastic band ?

Photons are not elastic bands.

I would not be too sure on that as energy seems very diverse these days  . The point is if you shun a beam of blue light on an object for example 1 second, the shorter wave length , a red light beam would deliver the same amount of energy but it would take nanoseconds longer because of the longer wave .
Consider this example as pulses of light rather than a constant beam .

Title: Re: Does light of different wavelengths have the same energy?
Post by: Kryptid on 16/10/2021 00:06:06
The point is if you shun a beam of blue light on an object for example 1 second, the shorter wave length , a red light beam would deliver the same amount of energy but it would take nanoseconds longer because of the longer wave .
Consider this example as pulses of light rather than a constant beam .

What do you mean by "shun"?

A photon with a shorter wavelength has more energy than a photon with a longer wavelength. That is a fact. The energy of a photon is given by E = hf, where "f" is the frequency. Since all light travels at the same speed in a vacuum, frequency is inversely proportional to wavelength.
Title: Re: Does light of different wavelengths have the same energy?
Post by: Black hole on 16/10/2021 04:08:58
The point is if you shun a beam of blue light on an object for example 1 second, the shorter wave length , a red light beam would deliver the same amount of energy but it would take nanoseconds longer because of the longer wave .
Consider this example as pulses of light rather than a constant beam .

What do you mean by "shun"?

A photon with a shorter wavelength has more energy than a photon with a longer wavelength. That is a fact. The energy of a photon is given by E = hf, where "f" is the frequency. Since all light travels at the same speed in a vacuum, frequency is inversely proportional to wavelength.

''Shun'' means shine !

If you are stretching anything by force , the energy is divided but remains the same value .

You are talking about magnitude as opposed quantity!

Title: Re: Does light of different wavelengths have the same energy?
Post by: Kryptid on 16/10/2021 04:50:56

If you are stretching anything by force , the energy is divided but remains the same value .

You are talking about magnitude as opposed quantity!

Stretching an elastic band actually adds energy to it, so even in your elastic band analogy the energy isn't the same.