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About Physicist13

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    Star Forming

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  1. blow with little air..not frm a can! if you must but tht dust wont make a jot of difference to image or viewing quality. dont worry about it.
  2. from what I see you are calculating a formula for the uncertainty disc from uncertainty princip saying tht the momentum/wavelength is known. This gives a formula for a 'blob' of light passing through an aperture..but does not account for any diffraction. The airy disc is a diffraction feature and the 1.22 comes from the zero in the Bessel function. You might want to calc the 'smudge' of the airy disc due to the uncertainty princip.
  3. A little chipping in. The orig Q was also about "spin". this is a quantum property that is measurable but the word spin is just a handle..like colour is to quarks. The quantum spin behave a bit like classical spin which is why the term is used but as in all quantum realms is v different too. So try not to thing of it as something actually rotating like a top.... no point trying to picture anything in quantum tbh!! Yes Physicists do use specific words and phases which are often not clear and too many maybe...our main language is mathematics so to explain outside that phrases are used
  4. sorry strongly disagree!!! This is whole point of the SI system!!! Units of angle is the radian and should be used. The CIMP recognise other units, such as degrees. With globalisation it is increasingly important that all countries use the same units and with national standards that maintain those units and their traceability to the SI system. P (metrologist! ) see www.bipm.org and links also ISO site. plus UK national measurement lab.... npl.co.uk
  5. yes it does dep on where the star is in its cycle..mass etc etc.... balance of sev factors.
  6. yep pretty much. Fusion is not a thermodynamic effect. Its a v diff way of producing energy and yes its the radiation pressure from this that countering gravity...not the fact that the core is hot. The radiation pressure is a net outward force as you say. Once the fuel is exhaused fusion stops so the radiation pressure drops dramatically. So the core then contracts under gravity and compresses more and heats akin to normal heating of a compressed gas. Once hot enough for the next fusion process to kick in then rad pressure is active again so further core compression halts....this process repe
  7. hmmm trying to stay out of this ;)...but just to say. So far special Rel, Gen rel and QM have passed all the tests thrown at them to within the best achievable experimental limits. Experimentalists constantly try to do more precise measurements to keep testing these theories and possibly show a brakedown. In general, theorists modify or more rarely come up with new or refined theories that also have to pass all current tests but may also predict some new features which are measurable. Hypothetical arguments can be stimulating and thought provoking but must lead to some prediction of a verifiab
  8. oh a light pollution filter will mk big differance unless you are in a partic dark sky area. Clip in ones for Canon are good.
  9. yep!! def interact and learn You WILL need to get motor for mount next! you have to track I'm afraid. bby steps though! Personally I'd keep off and software for now..just get used to doing single exp..focusing and tracking.... Most of all have FUN!!!
  10. steer away from planetary with DSLR (at least for now) ..its poss but much better and easier with "webcam" . High frame rate is required..over 100fps really... yes, high f ratio needed too. Moon is fine as single exp will do...although it does benifit from fast multi exp too. P
  11. Hi. I'd suggest you go in baby steps! Get used to the DSLR first. Why not try piggy back or ditect on your mount? Go for easy objects and use camera lenses to start. Always take in RAW ! learn to focus and get feel for how long an exp you can do before you notice trailing. Then try fixing to scope , and again go for big east targets..cluster?. Ring neb is v small. I'd avoid Jup and planets for now as diff techniques is needed. a bahtinov mask will be very useful. P
  12. the matter/anti-matter inbalance is v v interesting.....work is going on to produce long lived anti-hydrogen with aim to study and compare to normal H....spectroscopy may show differences....nobel on way to those who find something...
  13. I'd say try and do an OU course or some online course but one where you can interact with people and ask questions. FOr QM you def need the maths and learn the ability to interpret the maths in the physical world..bizarre though the results are. Books are great but it def needs human interaction too.... Dont be scared!! I got O level B in maths and C in A level!..... enthusiasm is the key!! P
  14. The random noise reduces as square root of number of images stacked, and the "signal" part goes as N , so overall signal to noise goes as root N . Basically a way of making say 10x1min exp=1x10min. Before anyone cherps up...read noise reduces this gain in SNR, which is why its important to get subs out of read noise if posisble.
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