andrew s

Thanks @ollypenrice, what I actually think is that it is not a matter of intellect but of data. We currently don't have the means to "observe" the high energy and density that occurred prior to 10^-10s nor do we have the ability to "observe" down at or below the plank scale. If we ever do have the technology to do this (primordial gravity waves are a possibility) then as with the current mysteries from hadrons to galaxy clusters we would make a good fist of it. However, on the specific question of where the Universe came from I don't think there is an answer that does not lead to an infinite regression. If it came from somewhere then where did that somewhere come from and so on. I am content with, that it just is, and describing its evolution as best we can. Regards Andrew

I don't need to you made the claim not I. Recall, absense of proof is not proof of absense. I would however, point out the vast range of observations we have explained from the very small to the very large and as I posted before no theory can be proven. It is just good or bad at explaining what we observe. I was being tongue in cheek but I balk at the phrase "just a theory" it implies there could be more which is why I asked what you thought was proven. Personally I don't think anything is in the sciences. If you seek certainty you need another route to knowledge one, for example, that is forbidden to be discussed on this forum. Regards Andrew

What, if anything, in your view is proven? The proposition that, as a species, we don't have intelligence to understand where the Universe came from is just an unproven speculation on your part. 🤔 Regards Andrew

I am sure your happy (ish) with the classical electromagnetic field and they are more or less generalisations of that. Everywhere, they have a value which could be a scalar like temperature or a vector like wind speed. Unfortunately, I don't know a good introduction to recommend to you. I am sure you will enjoy Carlo's book although he can be left field. Not always a bad thing. Regards Andrew

Great report. I follow Red Dwarf stars hoping to catch flares as many are feisty little beasts. Regards Andrew

I don't think you need worry if you follow the avxiv.org listings say on astrophysics you will see papers on many "fringe" theories, MOND for example. Regards Andrew

No scientific theory is a fact and no facts/observations are theory independent. Theory is judged on how well it works. Any particular theory you feel is being neglected? Regards Andrew

I fully agree. We have got very close at 10 ^-10s. The best theories before that are the inflationary ones which have an energy dense "inflation" field which drives an inflationary period. They were invented to solve some issues with the uniformity of the CMB so by design they have some connections with observation. In these model the LCDM singularity is avoided but don't really explain much that I think would satisfy you. One interesting game in physics is rather than propose new dimensions (which some do) you propose more fields e.g. Higgs, Inflation etc. I am sure the Universe (i.e. everything) is nothing like our perceptions of it nonetheless we have made a good first at understanding it in our frame of reference. However, in my view any science worthy of the name has to relate theory to observation even if that limits what it can address. Regards Andrew PS I agree with a lot in "The Trouble With Physics"

@ollypenrice a challenging post to review on a hot Friday afternoon. Where it not a diet day it would be done while downing one or two glasses of chilled wine. Yes I put ice in mine a habit from too many hot airport lounges. To business. Interestingly in science there is no present, before/past or after/future! Our everyday concept of time is not compatible with the relativity of simultaneity. Each event has it's own past and future light cones but it shares no present with another event nor a complete past or future light cone! Rather, than our common sense idea of time (some times referred to as manifest time) we have many times associated with different systems of coordinates. Perhaps the most useful in cosmology are those attached to the Hubble flow (i.e. at "rest" with respect to the microwave background). for the super nerd try "What Makes time Special" by Craig Callender a 300 page book. This is not quite correct as I understand it. Our best current model (LCDM) if projected backwards has two factors going to zero. Firstly the time coordinate 't', as discussed above, and secondly the spatial scale factor 'a'. However, it is still spatially infinite up to that point!!!! Formally the point t =0 a=0 is outside space time but remember space time is just geometry. We don't have any observational evidence past the release of the cosmic microwave background but know science (particle physics etc.) takes us back to ~10^-10s. Before that all we can say is nothing. See "An introduction to Modern Cosmology" by Andrew Liddle - minor nerd level. Indeed we can speculate at will, however, there is not one iota of evidence for additional dimensions. Our two most fundamental theories General Relativity and Quantum Field Theory are both formulated with one time and three space dimensions. as is Special Relativity,classical physics and all physical theories that have observation support. Many scientists make a living, at our expense, proposing more, in for example string theory or equally grandly multi-verses , I will take note of these speculations when they explain some as yet unexplained observation. Regards Andrew PS Give me food...…….

You had me worried with your title that it was going to be a black rectangular parallelapiped. Regards Andrew

I think it's time this thread went quietly into the night. Regards Andrew

Are we all not star dust? Regards Andrew.

My dad was driving home with the window open he felt a glancing blow to his head. When he got home there was a recovering pidgeon on the back seat. Regards Andrew

I was not commenting on your post but the one above. Regards Andrew

I am pleased for those who ordered these mounts to see that they are shipping. However, making a merit out of poor delivery and customer service, be it JTW or AP is in my opinion perverse. Regards Andrew

You need to find roughly where it is. Use just the scope and point it at a distant outside view, then with no camera or eyepiece find where the image focuses on a bit of white card. Focuser fully in so you can see the card. This tell you where the chip in the camera needs to be. Regards Andrew

Fashion plays a role even in Astronomy. One or other aspect takes over, like hem length in dresses, being highlighted over some other factor. Short easy to mount and house v long and more difficult. As technology opens up other options they rise in popularity to fall back as the wave passes. We are fortunate to have a wide range of options over an unimaginable price range. Regards Andrew

Science applies to the real world of observation . Yes your eyes will have a major effect, as I mentioned accomodation but also visual accruity, dark adaption, practice and skill Regards Andrew

Are two things at play here. Depth of field refers to how well or easily you can focus. Even the moon is so far away relatively that the whole disc would be in focus if the telescope field were flat. However, most refractors naturally have a curve focal plane. The shorter the focal length the greater the curvature. Maybe this is the reason for preferring the longer focal length. When young your eyes can easily accomodate for this but with age less so. Regards Andrew

@markse68 an interesting read. Unfortunately, the translation gets a key word wrong but my wife helped out. I think there are 3 things discussed. Stray light from off axis stars and polished vains. This is fairly obvious and not a good idea. The increase in projected width of the vains as you go off axis. Again fairly obvious. Increase in the apparant width of the spider due to a cold boundary layer forming on the vain. I have not considered or come across this before. I don't know how real this is v normal tube seeing issues. Some professional scopes use a T shaped spider to keep the projected area constant. It would also hide the boundary layer if there where one. Regards Andrew

I don't think it would impact the diffraction directly. However the vains and mirror support will add to the seeing within the tube. Only the upper and lower parts of the vains "see" the sky (lower via the main mirror) the rest face the walls. As the heat loss depends on the temperature gradient as well as the surface emissivity the main heat loss and source of seeing is, I suspect, the main mirror. Regards Andrew PS if you provide a link I will look at what they say.

Two very different moments. 1) Many years ago I was quietly observing when one of my cat lept onto my back and just hung there. Heart stopping. 2) Just leaving for the plane to go on holiday when I noticed some smoke near the observatory. I thought "Hum, that bonfire is rather close." . On checking the whole thing had burnt to the ground. Jaw dropping. Regards Andrew

Yes it would. It is the fact the vanes block the light that cause the diffraction pattern. Regards Andrew

Sounds very interesting. Hope it goes well. Regards Andrew

Rewarding oneself is highly recommended especially if it involves astronomy. Good luck with the PhD what is the program for or is it a state secret ? Regards Andrew