RE: [asa] Near Starlight Problem; Adam would never see all of Orion's belt?

Thanks Gordon, this is interesting. I'll look into this some more. I
assume this is an actual measurement that was done with the Magellanic cloud
supernova, not just a theoretical idea of a measurement that could be done?

Jon Tandy

-----Original Message-----
From: asa-owner@lists.calvin.edu [mailto:asa-owner@lists.calvin.edu] On
Behalf Of gordon brown
Sent: Monday, February 23, 2009 10:41 PM
To: asa@calvin.edu
Subject: RE: [asa] Near Starlight Problem; Adam would never see all of
Orion's belt?

Jon,

The calculation was based on trigonometry. The supernova lit up the gas
cloud that surrounded it. At some time after the explosion was seen, say one
year to make it simple, one could measure in angular measure the radius of
the sphere that was lit up. The actual length of this radius would be one
light year. This gives you the length of one side of a right triangle and
the angle opposite to it. Then, knowing the tangent of that angle, one can
compute the length of the other leg of the triangle, i.e.
the distance in light years to the supernova. By light years I would mean
light years at the time of the explosion. Thus if light traveled faster at
the time when the explosion occurred, a light year would be a greater
distance than it is now, and the distance to the star measured, say, in
kilometers would be greater, and since supposedly light has been slowing
down subsequently, it would take longer to get here.

Gordon Brown (ASA member)

On Mon, 23 Feb 2009, Jon Tandy wrote:

> Gordon,
>
> Explain this further, if you could. The typical suggestion of the
> speed of light being faster in the past is in contrast with the
> assumption that the speed of light is constant. The distances I
> assume are measured by independent means (parallax for near stars,
> increasingly complex measurements for farther stars). Thus the time
> is t=c/d. The idea being that if light moved faster in the past, then
> by our uniformity assumption, the time would be less, and so on.
>
> How do you say that the change in speed of light would result in
> recalculation of distance? (I can imagine that some of the distance
> measurement techniques might be based on the speed of electromagnetic
> waves; i.e., light, but that wouldn't necessarily be true for parallax
> measurements of close stars.) What does that have to do with the
supernova?
>
> Jon Tandy
>
> -----Original Message-----
> From: asa-owner@lists.calvin.edu [mailto:asa-owner@lists.calvin.edu]
> On Behalf Of gordon brown
> Sent: Monday, February 23, 2009 6:28 PM
> To: asa@calvin.edu
> Subject: Re: [asa] Near Starlight Problem; Adam would never see all of
> Orion's belt?
> If the speed of light really was faster when the supernova in the
> Magellanic cloud occurred, then the recalculation of its distance
> would give a greater distance since the light year at that time would have
had a greater value.
> Thus it would be an even greater problem for YEC.
>
> Gordon Brown (ASA member)
>
>
>
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Received on Tue Feb 24 11:15:08 2009