iantaylor2uk

There were no particles with mass straight after the big bang. Once particles with mass appeared, gravity could attract other particles. If you say that the potential energy of something in empty space where there is no gravity is zero, then if you imagine something on the earth, you have to put lots of (kinetic) energy to get it into this position. Therefore you have to add energy to get something to a position where the total energy is zero, so to make this work the potential energy must be negative.

I've stored my losmandy G11 in the shed since I bought it in 2009. Provided the shed doesn't leak you should be fine.

If you have a 60 kWh battery in the EV, then when it is fully charged the energy in the battery will be 216 MJ (since 1 kWh is 3.6 MJ). So the change in mass of a fully charged battery compared to a discharged battery is only about 2.4 micrograms.

I have the 071 camera and have not had too many problems with dew or frosting up, although that may be because I only cool to 0 or -5 C, and I keep the dew heater switched on. If you can pick up a 2nd hand one cheaply it would be a good buy. If I had to buy a new camera it would be the 533 or 2600.

Personally I would rather buy a product that is in large scale mass production than buy off a local company that only makes a handful of products every year. CMOS astro cameras are essentially riding on the back of good quality sensors used in the very large photography market (Sony, Nikon, Canon cameras etc.).

If you use the spreadsheets that are available for estimating exposure lengths for ZWO cameras, you find that you should go around 3x longer for a filter like the L-Enhance, compared to a simple UV/IR filter. If it is a specific narrowband filter you would need to go longer, that's true.

You can go shorter if you put the gain up. This also has the benefit of getting you lower noise. If I'm imaging with a UV/IR filter I usually use unity gain (90 on my ZWO 071) and exposures of 30 or 60 seconds, If I'm using an L-Enhance filter I up the gain to 200 (max gain on the camera is 240) and use exposures of 180 secs.

I don't think people realize that the dark current graphs of these chips are plotted on a logarithmic scale. There is no need to go to -10 or lower with these sensors, you are just wasting electricity. Cooling to 0 or -5 will usually be good enough.

With the last few days being clear, I started imaging again (last time was in May). I used my new RST-135 mount in anger for the first time, and guiding was great, with the total RMS averaging 0.7" over two three hour periods. I took around 60 three minute images of both objects using a ZWO 071 camera on a Takahashi TSA 102 refractor (focal length 814mm) with L-Enhance filter and 1x flattener. I used DSS for stacking and Nebulosity 4 for processing.

Just reflecting on this topic more. Most physics ends up with differential equations, which are deterministic, but often lead to unpredictable outcomes unless the boundary conditions are known to infinite precision (which is clearly impossible). For example, in weather prediction, the differential equations for fluid flow (air is treated as a fluid) are well known, but since the boundary conditions are only poorly known, a range of different boundary conditions are used (consistent with measurements from a discrete number of weather stations) and many simulations are run - if the weather system is in a "stable" configuration, then good weather predictions are available for 5-10 days ahead. If, however, the weather system is in a "chaotic" configuration, then the forecasters just give probabilities of the possible different outcomes. Although the differential equations are deterministic, our lack of knowledge of the right boundary conditions means we cannot make precise predictions. However, the issue with relying on differential equations for physics is that it is assumed everything is continuous. It is thought that space is not continuous at the Planck scale, and so you would think the best way to treat space-time is to use difference equations (rather than differential equations). In practice, numerical simulation of differential equatioins (by finite difference methods) basically takes this approach, but analytical solutions of differential equations may not be accurate when you get down to the Planck scale and instead you may need to solve discrete difference equations. This is why some researchers are trying to "build up" space time from simple rules (e.g. Wolfram's cellular automata approach, or the approach used by loop quantum gravity theorists).

I use a Lenovo Tab P11 Plus, which is a great tablet, and runs the ASI Air app with no problems (although I haven't yet tried using Sky Atlas feature - I usually just input the M number or NGC number of the object I want to image and do a goto).

The whole point is that quantum mechanics says that the initial conditions can never be known exactly which is precisely why deterministic systems can be unpredictable. I suggest you look up references that describe iterations of the logistic equation and/or Julia sets in maths.

The work of Mandelbrot & others has shown that in nature, complex systems very simply arise from simple, often scale-free rules. Although they may, in theory, be deterministic, they are essentially unpredictable. Space-time most likely arises from simple rules, which we don't yet know. However we do know from quantum mechanics that the initial conditions will never be known perfectly, so space-time will most likely be an example of a deterministic unpredictable system, and since we, and our brains, are all within space-time, this will also apply to us.

Just in reply to vlaiv, it is well known, in both physics and maths, that there are many complex systems which are completely deterministic, but essentially unpredictable (weather systems are one example) and it is very likely the human brain is another example. So free will could actually just be the chaos of a complex deterministic system!

I bought a WO GT81 IV in mid 2021 and it is definitely a triplet and has the camera rotator. I like the strip on top of the tube rings as it can be used as a carrier and is also where I mount a finder scope.

I don't think a dog would come up with new mathematical ideas: https://www.ox.ac.uk/news/2021-12-01-machine-learning-helps-mathematicians-make-new-connections

There are various types of AI - some of the simplest are no better than simple statistical regression analysis. In others, there is "supervised" learning, in which the AI model is "trained" on data, and then it is used on other data, although these methods can only interpolate, not extrapolate. However, one of the most interesting types of AI is "unsupervised" learning, where the AI program is programmed to "train itself". This was the approach taken by the Deepmind team when it developed a program to play the game Go. The AI trained itself and became good enough to beat the Go world champion, and also produced some very unexpected moves (move 37, game two) during the games (for more details see: https://www.deepmind.com/research/highlighted-research/alphago and https://www.wired.com/2016/03/two-moves-alphago-lee-sedol-redefined-future/) For unsupervised AI, although the model has been programmed by a human, there is no telling what the final outcome of the AI will be, as we cannot see "under the bonnet" to see how the AI teaches itself, or how it uses that learning to come up with improved algorithms. I would have thought that it would be the unsupervised AI that is the closest thing to human intelligence (as we basically teach ourselves, with the help of others, for the first 20 or so years of our lives).

Looks interesting. My personal view is that anyone interested in space-time and the physics of fundamental particles, and cosmology, would do well to take courses in solid state physics. In that discipline you learn about phase transitions and how complex behaviours emerge from simple building blocks, and many of these concepts are now being used in fundamental physics of the universe.

Not sure what the feet are like on the ZWO tripod but if they have a standard 3/8" thread you can get some Gitzmo flat big feet. I got some for my Innorel RT90C tripod and they are a big improvement over the standard feet they are supplied with. https://www.lcegroup.co.uk/New/Gitzo-GSF50-big-foot,-50mm,-set-of-3_94071.html

I think these cameras are also sold in Asia, USA, the Middle East etc where temperatures could easily reach 40C. You can always switch the cooling off.

Yes if keep seeing flashes in your eyes get it checked out. The viscous layer covering the retina can dry out and when it peels off there is a chance the retina can get detached (which you definitely don't want). I saw flashes and a floater in my eye about 3 years ago, and the advice from the NHS phone line was to go straight to A&E.

I've got an RST 135 mount on the tripod, but there are cheaper harmonic mounts coming along.

I have an Innorel RT90C carbon fibre tripod, which weighs around 3kg, but can support up to 40 kg. I have a harmonic mount on the tripod which can be in equatorial mode or alt-az. Total weight of tripod and head is only around 6 kg, although you may need a counterweight if you are operating in alt-az mode. With a counterweight you can put a telescope on up to 18kg, or up to 13.5kg without the counterweight. I have found it to be a good lightweight set-up.

There are particles which as far as we know are point-like, such as the electron. For composite particles, like the proton, they are not point-like, so by definition they have a volume. The value may depend on how exactly you define volume. From a mathematical point of view, if something has a volume then it must also have a surface area. Again the value depends on your definition and how it is measured. I think most people would agree that Britain's coastline has a certain length, but may not realise that its value increases as the size of the measuring stick decreases.

I bought a tube from Amazon