Rømer and the speed of light 1676

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Rømer and the speed of light 1676

Postby TransFormer on October 24th, 2017, 7:50 pm 

Rømer and the speed of light 1676
Rømer's argumentation was the reason Descartes' view of instantaneous light propagation was abandoned in favor of the until now accepted view of light traveling at a high but finite speed. His arguments were quite simple, maybe a little too simple, but were universally accepted. By calculating the time it took for the closest moon of Jupiter to reappear from behind the planet, and multiplying the minimal differences between all the observations during a ten year period, Rømer was able to show that the differences when seen from different positions of the earth relative to Jupiter were far from negligible. He was then able to calculate the speed of light reasonably accurately, certainly for his time.

The question is whether the differences in the times of eclipse and reappearance of the moon cannot be interpreted differently, without involving the idea that it takes time for light to travel through space. We all know that when looking through the telescope at a planet like Jupiter, we do not see it rotating about its axis, or orbiting the sun. We get each time a snapshot of a frozen moment in time, and the changes to the images we receive occur in jumps without any intermediate states. This is understood as the effect of parallax, or more simply resolution. Because of the distance two points separated by relatively large distances will appear to our perception as one, and it takes time before we notice the difference between one position and another.

This is exactly the situation which Rømer is analyzing, but instead of understanding it as a case of parallax and resolution, he chooses a very specific approach. He considers the time it takes for astronomers to observe the disappearance or reappearance of Jupiter's moon as a fact that needs no further explanation. If we see the moon appearing at time t that is because the moon appeared at time t. And if we notice that when the earth is at another position, farther from Jupiter, and the moon appears or disappears at time t+x, then x must be caused by the longer distance between the earth and Jupiter.

This is much too easily discounting the fact that we only see immediately the differences between one view and another when we are very close to the object. It is not surprising that Jupiter's moon seems to appear or disappear at a later time than when the earth is closer to Jupiter. The larger the distance between the earth and Jupiter, the more time it will take us to notice a difference between two consecutive moments.

In other words, whatever Rømer and everybody after him might think, he did not prove that it takes time for light to travel through space, and his calculations concerning the speed of light, whatever their merit, are based on invalid arguments.

Re: Rømer and the speed of light 1676

Postby TheVat on October 25th, 2017, 11:51 am 

Hiya, Odal. This may be helpful. A lot has been done, since Romer....


And don't forget cavity resonance, interferometry, and a host of other methods that provide further confirmation of c.
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Re: Rømer and the speed of light 1676

Postby mitchellmckain on October 26th, 2017, 3:40 am 

Science isn't really about proving things absolutely, but about what is reasonable considering the evidence. Romer's finding showed that it is a little more reasonable to accept that light has a finite speed. But the conclusions of science are not founded on singular findings like this. We keep on looking and keep on testing and thus we find more and more reasons why certain conclusions are the more reasonable ones. By now the accumulation of evidence on this particular issue is overwhelming and to believe that light does not travel at a finite speed by an observer's reckoning, is now extremely unreasonable.
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Re: Rømer and the speed of light 1676

Postby BurtJordaan on October 26th, 2017, 6:44 am 

I suppose you guys have noted that Transformer has been banned immediately by Admin, due to ban evasion. He is undercover Odal. ;)
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