Re: does light travel forever?

On 18 Jan 2006 12:35:21 -0800, in talk.origins , "David Ewan Kahana"
<dek@xxxxxxx> in
<1137616521.350064.65220@xxxxxxxxxxxxxxxxxxxxxxxxxxxx> wrote:

>Denis Loubet wrote:
>> "John Vreeland" <vreejack@xxxxxxxxxxx> wrote in message
>> news:67rps1hmmvltmvko3qb0n9ui20lj1nbt36@xxxxxxxxxx
>> > On 16 Jan 2006 23:11:38 -0800, ck19bla@xxxxxxx opined:
>> >
>
>[snip]
>
>>
>> I hereby present a stupid question:
>>
>
>There are no stupid questions, only stupid answers.
>
>
>> 1. I assume a photon experiences time dilation just like any object
>> traveling near the speed of light.
>>
>
>Only another photon could notice it however.
>
>> 2. Since the photon is traveling AT the speed of light, in a vacuum, I
>> assume it's time dilation is total, and it experiences no passage of time
>> whatsoever.
>>
>
>Yes. Proper time vanishes along the path of a photon.
>If you could travel along such a path, then there would
>be no passage of time.
>
>> 3. 1 and 2 being the case, how can a photon lose energy? From the photon's
>> point of view, there's no time for it to lose energy.
>>
>>
>
>It loses energy from the point of view of observers who are
>not comoving with the photon. Instead they are comoving
>with the expanding universe.
>
>As far as an observer who is comoving with a photon
>is concerned, a photon has no energy to lose.
>
>Its rest mass is zero, so if you could move together with it,
>its frequency would also be zero, since no proper time passes.
>Hence its energy is also zero from E=h*nu.
>
If you were moving along with the photon you would not notice it,
would you? (I guess you would not because not time would elapse for
you to notice it, but I ignore that for my question.) If it has no
energy/mass does it exist for you, its fellow traveler?

--
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