Path: ...!fu-berlin.de!uni-berlin.de!individual.net!not-for-mail
From: Thomas Heger <ttt_heg@web.de>
Newsgroups: sci.physics.relativity
Subject: Re: Relativistic aberration
Date: Thu, 18 Jul 2024 08:33:27 +0200
Lines: 82
Message-ID: <lfrr9lF22urU4@mid.individual.net>
References: <QsysQnpetTSlB_zDsjAhnCKqnbg@jntp>
 <1b0910c819bb031839b21557a19c75be@www.novabbs.com>
 <_hiIkN_NB6Jm2XOJZeHK7Fy9L2E@jntp>
 <1f081cbe82f7c86f1463b0bf5ad957a9@www.novabbs.com>
 <9mrYetkghLXwIcwZUl4c8b3LTKI@jntp>
 <f21b77862f36ab6a27fd237fda9661f8@www.novabbs.com>
 <Rsj9fwaYx7xWTx_LjgnuDLRLG0M@jntp>
 <6f498e8663ec0b05b9cd9e03df9b4de4@www.novabbs.com>
 <tWsKauuW6XViPa1OVHe8GAFt0pY@jntp>
 <0cb92f486425b83cdc71dbdea3093427@www.novabbs.com>
 <2EXLnr_H9bJJ03uqOqvAke2Stu0@jntp>
 <40a7f3651fa003ba04b12ddd79ee55b1@www.novabbs.com>
 <lfp8pbFkr1mU1@mid.individual.net>
 <277d12ea32119cb16056773223fe1a45@www.novabbs.com>
Mime-Version: 1.0
Content-Type: text/plain; charset=UTF-8; format=flowed
Content-Transfer-Encoding: 8bit
X-Trace: individual.net JRz/sgKEhXINX9OjXJplWQ5DspOj+iQHPYRDVPXDXuuElTl0Y2
Cancel-Lock: sha1:RhralKypNZiCY0AMH8L+HFDy+E0= sha256:dGS7p8hSYcPfSlqUKoA/YEu7W844X4wsMPYKoPEjAlg=
User-Agent: Mozilla Thunderbird
Content-Language: de-DE
In-Reply-To: <277d12ea32119cb16056773223fe1a45@www.novabbs.com>
Bytes: 4299

Am Mittwoch000017, 17.07.2024 um 14:05 schrieb gharnagel:
> On Wed, 17 Jul 2024 7:05:15 +0000, Thomas Heger wrote:
>>
>> Am Dienstag000016, 16.07.2024 um 16:47 schrieb gharnagel:
>> >
>> > "Why is the speed of light so slow when the universe is such a really,
>> > really big place?" -- G. L. Harnagel
>>
>> This is a tautology:
>>
>> What we see in the night sky is actually our own past light-cone.
> 
> Ah, but if we can develop tachyon astronomy, that will not be true!

Well, if light would speed up somehow in remote corners of the universe, 
we would still see what we see in the night sky, if this phenomenon 
would not change in observable timespans.

Possibly there are tachyons, but those are invisible anyhow, because we 
can see only light and light moves with light speed and tachyons don't.


> 
>> This means: light is relatively slow for the wastness of the universe,
>> hence we can see everything only with a certain delay and the further
>> away, the longer the delay, according to x = c* t
>> (with x= distance in meters, t = delay in seconds).
>>
>> This 'longer away' is usually measured in light years and the delay in
>> years.
>>
>> Since the night sky shows only a delayed image of past events, the speed
>> of light cancels out of the equations and we can put any value into it
>> and always get a valid picture of the universe.
>>
>> So we only assume, that light moves always with ~300 million meters per
>> second through the entire universe.
>>
>> But if light would speed up or slow down, we would not be able to
>> measure this, because we always see the own light cone in the night sky
>> and c is already embedded into it (for whatever a value c actually has
>> in outer space).
>>
>> TH
> 
> Ah, but the fine structure constant, which is pertinent to how stars
> shine,
> includes the speed of light.  That implies that c is the same throughout
> space and time, n'est-ce pas?


Well possibly.

What I wanted to say is this:

what we see in the night sky is light, that stems from remote places in 
the universe.

Since light is very fast, but space is also very large, we have a 
significant delay for the travel from such remote place to us observers.

This makes the image we see a little unreal, because it is not only old, 
but also 'layered in time'.

To untangle this picture and create kind of realistic picture of the 
universe, we would need the distance to those remote places.

Since we only have light to see, we can assume c=~ 300 million meters/s 
as light speed.

But what if that is not always the case???

Could we somehow find out??

No, since c is already used to determine the distance to these events.

If now c alters mysteriously along the path, we had to determine the 
distance by other means (which we do not have), hence cannot measure, 
whether or not c stays always the same.

TH