XPost: sci.physics.relativity
From: ttt_heg@web.de
Am Montag000015, 15.09.2025 um 13:37 schrieb J. J. Lodder:
...
>>> | We see stars in 10000 light years distance as they were and
>>> | where they had been 10000 years ago, while we see our Sun as
>>> | the Sun has been 8 minutes ago.
>>> | That is a HUGE difference.
>>> |
>>> | The picture we see is actually 'layered in time', while
>>> | the universe isn't.
>>> |
>>> | Therefore we see things, which are not real and which do
>>> | not belong to the same time.
>>>
>>> We see that the star was real 10000 years ago, and if it was
>>> a main sequence star then, we know that it still is a real
>>> main sequence star now.
>>>
>>> It is indeed a weird idea that a star that was real 10000 years
>>> ago is not real now.
>>>
>>> What do you think the stars we see in the telescope are?
>>> Mirages?
>>>
>>> We know that the star and the Sun were 10000 light years
>>> from Each other 10000 years ago, and we know that the star
>>> and the Sun still are ~10000 light years away from each other.
>>
>> Ten-thousand years is actually nothing in cosmology, which deals with
>> millions of light-years.
>>
>> well, now we have a 'little' problem:
>>
>> if we have millions of years as delay, then we can't call our impression
>> of the stars 'real'.
>>
>> It is like a postcard from the last century, which is delivered today.
>>
>> sure, the picture and the content were once real.
>>
>> But the sender might already be dead.
>>
>>
>>
>>> And for million years the two stars have transferred energy
>>> (light) to each other, and will keep doing so for million
>>> of years.
>>
>>
>> The main problem isn't that, but that distance is very hard to estimate
>> in cosmology.
>>
>> Since everything moves within our galaxy and within the rest of the
>> universe, an error in measurement of the distance would be equal to an
>> error in the positions.
>>
>> We could see a star moving to, say, the left in the foreground and a
>> star moving to the right in the background at the same time at a
>> relatively close position.
>>
>> And because it's so hard to determine the true distance, we could
>> actually be in error, which star is in the background and which one is
>> actually nearer to us.
>>
>> So we could find a relation between two seemingly close stars, which
>> were never that close.
>>
>>> The stars are at any time living side by side ~10000 light years
>>> from each other.
>>
>> That is't necessarily the case, just because you see two stars that way.
>>
>>> That we happen to live close to one of them doesn't make them
>>> "belong to separate times."
>>>
>>> They are both living at the same time.
>> 'living' is not the right phrase for pictures of stars.
>>
>> I meant:
>>
>> if you have a depth in a picture from the night sky of several thousand
>> light years, for instance, you need to consider, that background events
>> belong to a different time than foreground events.
>>
>> The discrepancy is actually huge and can easily be millions of years.
>>
>> Therefore pictures of the backgrond stars and the forground stars do not
>> belong together, but should be corrected because of different delays.
>>
>> Unfortunately we don't know the exact delay and we also don't know,
>> which stars are actually the background stars and which one belong to
>> the foreground.
>>
>> We only assume, that some theories are valid, which enable us to
>> estimate the distances.
>>
>> But those theories are most likely wrong.TH
>
> You really are decades behind the times.
> (and it is most of your opinions that are just plain wrong)
>
> FYI, in the meantime we have seen the Hipparcos and GAIA missions,
> and we have direct distance measurements (by parallax)
> of more than a billion stars, accurate to a few percent,
> all the way out to the galactic centre.
> Those stars have been measured repeatedly over the 10 years of the GAIA
> mission, so we also know their proper motions accurately.
>
If you see a star in say 1 million light years distance and some stars
in two million light years distance, than they belong to different times.
The difference is actually huge, because we're talking about one million
years, within which the stars had moved.
But you cannot even estimate the direction, into which they move (up,
down, left or right) because only the 'z-axis-movement' is measurable
(with red- or blueshift).
To measure the direction perpendicular to the direction of sight, you
would need to measure at least two positions of that star. But that
would take way too long for a single human beeing to become measurable.
So stars move and we don't even know towards were they move and not how
fast.
This would be quite unfortunate, if you want to estimate their current
distance in respect to each others, because they had 1 million years to
move and we don't know the direction.
Precision wouldn't help that much, because even the sharpest of all
telescopes cannot make the movement of distant stars faster. And for
geometrical reasons the angles to measure are very small, if the star is
millions of light years away.
> We do know the delays you worry about,
> and we do know which stars are near,
> and which are far away.
> We also know which stars are really double,
> and which are aligned by coincidence.
All we see is actually a picture. This picture was sent towards our
position long ago and the longer ago the further away.
Since everything moves, we had to correct the delay somehow, but can't
do that, because we cannot even know the correct distance.
What we could know in principle, even if that is heard to measure, that
is the direction ond the velocity of the movements of stars.
To bring all stars into the same 'time-sheet' we would need to measure
their individual path and calculate their position, where they were in
the considered time.
That is actually quite difficult and certainly annoying. That's why I
assume this had never been done.
> We have an accurate 3D map of the galaxy,
Well, I have doubts about that.
TH
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