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Everything posted by andrew s
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What came before the Big Bang
andrew s replied to Scotti G's topic in Physics, Space Science and Theories
In mathematics a singularity is in general a point or surface at which a given mathematical object is not defined. As that's very abstract so here is a simple example. Consider simple division of real numbers, e.g. 1/n. At the point n = 0 there is a singularity as division by zero is undefined. Informally we say it goes to infinity. In spacetime, it is similar, again informally, we say the curvature of space time becomes infinite. George Jones who posts on SGL said this on Physics Forums. "I am not sure that there is a completely accepted technical definition. Roughly, a spacetime is singular if there is a timelike curve having bounded acceleration (i.e, a worldline an observer could follow) that ends after a finite amount of proper time. Singular spacetimes have "edges". How come of it? By the Penrose-Hawking singularity theorems, any "reasonable" classical spacetime must be singular. Very roughly, in any "reasonable" classical spacetime, gravity is so stong that the fabric of spacetime gets ripped, thus creating an "edge"." Source https://www.physicsforums.com/threads/what-is-singularity.124016/ That is, if you or I approached a spacetime singularity carrying a clock when we got there and the clock would read a normal amount of time i.e. not infinity. Personally I would say the initial instant t = 0 is singular but I am not an expert. Regards Andrew -
Fascinating, thanks for posting. Regards Andrew
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Excellent form should follow function. DIY rules. Regards Andrew
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What came before the Big Bang
andrew s replied to Scotti G's topic in Physics, Space Science and Theories
I had no idea you felt like this. I am sorry. In this section I just try to put forward my best understanding of the science. I will refrain from commenting on your posts in future. Please accept my apologies. Regards Andrew -
What came before the Big Bang
andrew s replied to Scotti G's topic in Physics, Space Science and Theories
Just to show how easy it is. I propose a new Universe would have came, just now, from a Mini Cheddar but I just guzzled it so it did not. Regards Andrew -
What came before the Big Bang
andrew s replied to Scotti G's topic in Physics, Space Science and Theories
There is significant evidence supporting the current best model. Have you read the whole thread? Regards Andrew -
What came before the Big Bang
andrew s replied to Scotti G's topic in Physics, Space Science and Theories
There us no evidence for any of these speculations. When there is please post again. Regards Andrew -
What came before the Big Bang
andrew s replied to Scotti G's topic in Physics, Space Science and Theories
If I was being pedantic that maths does not break down. The maths is quite comfortable with these points just like it is comfortable with open and closed intervals. If you take the interval 0 to 1 on the real line you can chose to include 0 and 1 (closed interval) or exclude them (open interval) they has significant differences and no I am not going into them. What scientists will say us that it is an indication the physical theory breaks down at these points. That is it loses it predictive power. Regards Andrew -
What came before the Big Bang
andrew s replied to Scotti G's topic in Physics, Space Science and Theories
The current model is that the Universe is and always has been spatially infinite (or very close to it). So yes the hot dense state was everywhere. Unfortunately, even respected scientists make "popular" science comments that mislead. Nothing went bang. The term Big Bang was I tended as a put down. It is correct to say, as discussed above, we cannot go back to t = 0 but we can get very close. Formally t = 0 is outside our spacetime geometry as are the singularities in a Black Hole. Regards Andrew -
What came before the Big Bang
andrew s replied to Scotti G's topic in Physics, Space Science and Theories
It did not bang in anything. The idea of it being an explosion in anything is mistaken. It was in an initially very hot dense state and the "scale factor" has been increasing ever since causing it to cool and become less dense with time. There is no external view in which to view the expansion. In the current state of the Universe the scale factor increase is seen as the Hubble expansion. If you measure the distances between galaxies today you get one number. If you do it again some time later you get a larger distance. It's as if your ruler got shorter but it has not the scale factor has got larger. It a difficult concept I know but that's it. Regards Andrew -
Astronomy sales during the pandemic!
andrew s replied to FLO's topic in Sponsor Announcements and Offers
Just ordered one significant item and about to order another. I will be Buddha like and await nirvana with good grace. Regards Andrew -
What came before the Big Bang
andrew s replied to Scotti G's topic in Physics, Space Science and Theories
Hi @ollypenrice I agree with your position . It is interesting how the dominant ideas of the time impacts our model of the world. After the God controlled Universe we had the clockwork one following Newtonian mechanics and on into the current field theory models triggered by Faraday and Maxwell. The rise of information processing has led to serious speculation on informatics as the basis with ideas about the entropy of a black hole being related to its area and Archibald Wheeler's "It from bit". As for a simulation what does it bring? Only a return to an all powerful presence! It's not for me. Regards Andrew -
Would you drill a hole in a Takahashi?
andrew s replied to andrew s's topic in Discussions - Scopes / Whole setups
@JeremyS is the perfect gentleman whereas I am not and so he will let me win. Regards Andrew -
Problem collimating an ƒ/4 Newtonian
andrew s replied to Tailspin45's topic in Getting Started With Imaging
All Newtonian owners have all been there or done something similar. Regards Andrew -
Would you drill a hole in a Takahashi?
andrew s replied to andrew s's topic in Discussions - Scopes / Whole setups
Certainly, it would be fun. Regards Andrew PS not sure I could bring myself to look through a refractor! -
Would you drill a hole in a Takahashi?
andrew s replied to andrew s's topic in Discussions - Scopes / Whole setups
I still have a Pace RC200 mountain bike with the custom rectangular aluminium alloy frame with indents to save weight. No need for the drill on it. Regards Andrew -
Would you drill a hole in a Takahashi?
andrew s replied to andrew s's topic in Discussions - Scopes / Whole setups
Stop it @JeremyS your a very naughty boy. Regards Andrew -
Increase star size in gimp
andrew s replied to Chefgage's topic in Imaging - Image Processing, Help and Techniques
What about a Gaussian blur. Regards Andrew -
Would you drill a hole in a Takahashi?
andrew s replied to andrew s's topic in Discussions - Scopes / Whole setups
Not exactly sure where you think I should put it. Regards Andrew -
Back to basics - my ultimate system...
andrew s replied to andrew s's topic in Discussions - Scopes / Whole setups
The aim was in the thread title. I have a fully automated set up in Castillejar Spain. The aim here was to do some visual astronomy but avoiding the temptation to drift into automating, imaging etc. This purchase stops that unless I sell it. I was tempted by a driven Alt AZ mount but resisted. Memories of trials past led to adding the DSC. My eye sight is not good and trying to find say double stars was beyond me in my youth let alone now. Principally it will be the moon and planets. Regards Andrew -
Back to basics - my ultimate system...
andrew s replied to andrew s's topic in Discussions - Scopes / Whole setups
Thanks, I am sure that I will be pleased with it. My other mount is a Paramount ME II but it is in Spain so I can't stroke it any more. Regards Andrew -
Would you drill a hole in a Takahashi?
andrew s replied to andrew s's topic in Discussions - Scopes / Whole setups
Thanks. I will try the thermal box first. However, if I think it needs it it will go under the knife. For me it's all about function. You should have seen my home built Newtonians . Nothing to look at but held collimation even after drilling 3/4" holes. Regards Andrew -
Back to basics - my ultimate system...
andrew s replied to andrew s's topic in Discussions - Scopes / Whole setups
Mount ordered from FLO. Rowan AZ100 with the not quite back to basics DSC. Regards Andrew -
Would you drill a hole in a Takahashi?
andrew s replied to andrew s's topic in Discussions - Scopes / Whole setups
No chance. Regards Andrew -
Hi, I tend to add outriggers with either roofing lead or exercise weights added to balance things. Regards Andrew