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It’s also interesting how the speed of light was determined.

It involved timing of Jupiter’s moons coming around her when Jupiter is on this side of the sun...

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sparklite2, I heard Professor Richard Feynman discuss that in one of his lectures. It's fascinating. BTW, many of Feynman's introductory lectures on gravitation, etc. can be found on YouTube. I have converted a few to mp3 files and listened on the way to work. Great stuff!

Your example of Jupiter measurements is telling to me because it's decidedly of a "solar system scale". In other words, a great deal of (relative) accuracy can be arrived at through human built instruments.

However, when you consider that the center of our tiny solar system is calculated at 25,000 light years away and the closest other galaxy is 158,000 light years away. And the closest spiral galaxy, Andromeda is 2.5 million light years away.

When you consider those distances, human verification of deep space astronomical theories is a crap shoot.

To me as a layman, a science like astronomy is of a different realm, one where religious faith in man's abilities and deep ~~state~~ space science overpower the measurable probabilities that give precision to mechanical and electrical engineering.

Am I mistaken?

The speed of light measurements are done on Earth. The refinement of the figure has been ongoing for the past few hundred years. No, it’s not a crap shoot, and it’s not based on religious anything. What you’re experiencing there is projection.

https://www.physlink.com/education/askexperts/ae22.cfm

One of the most interesting courses I've taken online was an astrophysics course for non-science majors. I'm sorry but I can't remember where I found it.

Anyway, one of the things he talked about was measuring the speed at which an accretion disc rotates around its companion black hole. He said you can be careless with 3x or 4x , but lose credibility if you are careless with x² or x⁴. In other words, with the distances we're dealing with, engineering accuracy is not to be expected, but orders of magnitude may not be tossed lightly around.

Just for grins here's a tidbit of why we can never push something to light speed, and a use of e=mc².

Imagine a planet rolling around in its orbit. Anything moving has some amount of kinetic energy related to its mass and how fast it's moving. The kinetic energy of a baseball moving at ten miles an hour will give the catcher a little different experience at two hundred miles an hour. That's kinetic energy.

If we could accelerate our imaginary planet in its orbit by, say, pushing on it, its increased speed would also increase its kinetic energy. Kinetic energy, naturally, is a form of energy, which has the potential to be converted to mass at the rate of e=mc2, or solving for mass, m=e/c2. So by increasing kinetic energy, there is a corresponding increase in mass.

The increased mass makes it harder to push the planet faster, and as you speed along closer to light speed, the energy/mass conversion adds so much mass to the planet you can't push it any faster, and the mass gets jaw droppingly large. No wonder you can't push it any faster.