andrew s

No one has any idea of what is really going on. All we have are models more or less useful at predicting what we observe as goiog on. We could all be in a simulation run by transdimentional mice or the matrix. Personally I take a realist stance and believe in an external reality. However, I don't know what anything is in reality and challenge anyone to give an example of what is really real. Regards Andrew PS my last comment on this.

So what about the key constants pi, e which are transcendental with an infinite number of digits. Is the area of a unit circle not real? Is it truncated as there are more digits in pi than atoms in the observable universe? Regards Andrew

This is one of Zeno's paradoxes. It was solved by calculus and the proof that infinite series can converge to a finite number. Simply the increasing number of half steps is balanced by the decreasing time it takes to traverse them. Regards Andrew

Strange then that the two most successful physical theories Quantun Field Theory and General Relativity both are based on a continuous spacetime. Regards Andrew

Can you provide examples? Regards Andrew

@vlaiv we will just have to disagree on this. I don't accept that dividing up one universe leads to multiple trials. I basically reject the logic that is commonly applied in arguments along these lines. I respect your view but disagree. I don't have the motivation to go further into this. Regards Andrew

My view is that it does not go against all our understanding of nature. Your view on multiple copies of self, universes etc. is in my view mistaken. If you have an infinite number of trials then possibly you view could be true. However, we have just one universe (one instance) and in this case there is just one outcome. One you, one me, there is no statistical reason for replication. On a sphere the coming back on yourself could have had specific effects when the scale factor was small in the early universe before casually disconnection. I suspect this should be have left an imprint on the CMB. I think this will have been looked for. Regards Andrew

I don't agree with these conclusions. Can you define a finite Universe that fits our current understanding without bringing issues of its own? Recall space time is not infinite, it is only spatially finite. Space time is geometry. Are you willing to accept there are an infinite number of points on a line? And following that if you dive the line (however unevenly) both segments have the same infinite number of points as the first and each other? Just as problematic ? Regards Andrew

I think it is a combination of factors. We are able to model the cosmos well on the assumption of a flat simple topology without a boundary and on large scales isotropic in content. This leads to a spatially flat universe from t = 0 to today. It maybe that we can't see enough of the Universe to detect deviations. However many possible topologies and curvatures are ruled out by observation. Cantor put infinity on a firm mathematical footing defining different types although it drove him mad. I see infinity as just as well defined as any continuum measurement which is just as problematic in physics. Regards Andrew

I have seen boys from the black stuff but not the other way around. But then we had girls. Regards Andrew

Yes to the first question. Ignoring the sun just vanishing but in that spirit gravitational changes travel at the speed of light. There is a proof that if there is a speed limit (I.e. c) then there can only be one such limit. Regards Andrew

Welcome lots of likeminded people here. Regards Andrew

It's imaginary = ic (or not as it's dark) Regards Andrew

This is indeed a good question. You are quite right a true vacuum even if it exists could not be observed as observing it would require energy and stop it being a vacuum! However, there a regions where the interaction of light with the medium is so low the speed is effectively c. The interaction of light with matter is very complex and required QED to explain it. But a classical explanation of how light interacts with a transparent medium works well. As it is transparent no absorption takes place. As an em wave enters the medium its oscillating electric field causes the electron to oscillate in sympathy . They absorb some energy from the em field but re-radiate it slightly out of phase with the exciting field with the net result that the is speed is reduced. Regards Andrew

I have all my computers on UT all the time. Only my wife's laptop has local time. Can cause issues if I am an hour late for a date with her! OP glad you got it fixed. I found a bug in the Astro Physics firmware if you were at GMT + 0 and syncing with a computer. Regards Andrew

Yes but it can slide in the plane and take off from the plane (try it upside down on the ceiling) You need 6 suitably place point to fix an object in space. In a focuser you need two free for in out motion so that leaves four points. A Craford typically has 5 which is theoretically redundant but is good for loads that might bend the tube. Regards Andrew

Are the edges of the secondary blackened? These can cause reflection Regards Andrew

You could try flocking the inside of the focused tube first. Regards Andrew

Does the focuser tube extend into the light path? It could be adding the extra spike, as could the iris from the camera. Regards Andrew

Hi @ollypenrice, I know I know. I was being a little young in cheek. I am of the view that almost anything can be fascinating if you study it in depth. I have read up many obscure topics. I might even read the book. Regards Andrew PS But, in truth, it's just a large test particle for general relativity 🤔

Never looked for it. Just a lump of rock! Regards Andrew

I am with Paul, I gain weight as I drink wine and eat while the kit gets on with it. Automation is wonderful. Apart for the body shape. Regards Andrew

Must be fermions in charge and bosons workers! Regards Andrew

In the end I take comfort in the idea that we are all just density fluctuations in quantum fields with arbitrary boundaries. 🐳 All in all it's just another brick in the wall. Regards Andrew

Personally I think binning is a very crude way to improve S/N in an over sampled image. There are better techniques which can be exploit the over sampling e.g approaches based on wavelets or convolution, to reduce noise. If the noise is truly random the over sampling pushes its frequency higher, away from the lower resolution image, making them simpler to separate. I am planning to try some of these on my over sampled spectra but I think PI has implemented some of these methods for images. Regards Andrew