Toby Jug

8 hours ago, Sensei said:

Paper is made of wood. Freshly cut tree contains trace amount of radioactive isotope of Carbon C-14 with half life ~ 5730 years.

Hi Sensei (and others).   Hope you are well.

Kodak really were the experts in protecting sensitive equipment (like film) from radiation.  You're absolutely correct about naturally occurring radioisopes.  They could cope with most naturally occurring radioisotopes (and also the brief use of Radium to make fluorescent paint) and this is why they were quite selective about where their paper and similar packaging materials came from.  They were less able to cope with fall-out from nuclear testing.  But throughout all of this, Ultraviolet penetration through cardboard and paper wasn't a problem - it didn't penetrate their cardboard and strawboard packaging material.

Here's a short and interesting video (but I warn you it is a bit depressing).

3 hours ago, StringJunky said:

Verbatim UltraLife 4.7GB 8x Gold Archival Grade DVD-R claim 100 year life.

Hi everyone.  

String-Junky, you're absolutely right about it being just a CLAIM. 

Have you seen the warranty information on Verbatim's website for the product?   I've copied-and-pasted some of it.  It's the funniest thing I've seen all day.

Verbatim Americas, LLC warrants this product to be free from defects in material and workmanship. If this product is found to be defective, it will be replaced at no cost to you. You may return it with your original cash register receipt to the place of purchase or contact Verbatim. In the U.S. and Canada, call 800-538-8589. Product replacement is your sole remedy under this warranty, and this warranty does not apply to normal wear or to damage resulting from abnormal use, misuse, abuse, neglect or accident, or to any incompatibility or poor performance due to the specific computer software or hardware used.  VERBATIM WILL NOT BE LIABLE FOR DATA LOSS OR ANY INCIDENTAL, CONSEQUENTIAL OR SPECIAL......

   So, to para-phrase this -  if the disc failed in less than 100 years, you COULD be given a new BLANK disc.

@studiot   Thanks again.  I'm going to try and stay off this forum for a day and actually do some of the things I've spoken about, like read a book. 

I honestly don't know how you manage to make such pleasant replies each time.  I gave up a bit of time to answer a question about cardboard boxes only to become reasonably convinced that whatever that post was about it wasn't really about cardboard or protecting DVDs in a box.

Take care of yourself studiot and be careful what you spend your time on.

Nothing blocks UV completely.  100 kilometers of lead wouldn't do it but it would cut the proportion of UV passing through to such a small amount that we would say it had been completely stopped.

It's difficult to find actual data to show the proportion of UV blocked by cardboard but there is general concensus that only the highest energies UV-C are likely to penetrate to any significant amount.  Are your DVD's in a plastic case and is that case actually a polycarbonate?  We have a lot more data about the performance of polycarbonate and other plastics against UV.  The Kodak company were the experts in protecting sensitive materials from e-m radiation a few years ago and they used to wrap their ordinary film and also their x-ray film in a special type of paper* and put it in a carboard box.   Wrap your boxes with some siver foil (aluminium foil) if you're really worried because the cardboard and silver foil really will keep out almost all the UV.

Are you really interested in protecting your DVD's?  There are similar posts all over other forums with the same pictures and the name Gamer87.  Are you trying to boost the ranking of some website in the google search engine or something?

* Late editing:  The paper wasn't even that "special", it was just paper.  It's just that their biggest problem was some contamination in that paper.  Most paper mills produced paper with trace amounts of radioactive elements and that would obviously damage the film.

51 minutes ago, gamer87 said:

this image that I posted the rays cross penetrate the cardboard these rays is UV?

No, not quite.

Raios Gamma  = Gamma Rays.         Raios X  =  X rays.

  Both of these are electro-magnetic radiations with much higher energies than visibile light.  UV is much more like visible light.

Hi.

Looks like you've had plenty of good advice.  UV is not that different from visible light, so unless your cardboard is not like most cardboard (a conventional mesh of cellulose fibres) you'll be fine.

However, the bigger problem may be heat build up.  The light-coloured and glossy boxes you have in your photos are the safer ones, these will reflect most of the light.  The black and matt finish cardboard boxes will just absorb the light (including UV) and get both the box and it's contents hot.  Plastic DVD's and CD's warp in the heat and this will be a bigger problem than anything else.  Don't put your dark boxes directly in the window and keep the room at normal temperature and you'll be fine.  In my limited experience DVD's will soften enough at about 40'C that they will be unuseable after a few days unless you're also very careful about how you stacked them to keep the presure over their surface as uniform as possible.

Before discussing any more possibilities you should be aware that recordable DVD's and CD's were never meant to last forever.  You must make back-up's of important data and do this on regular basis (maybe get the DVD's out and make fresh copies every couple of years).  Nothing you do is going to stop all e-m radiation and chemical reactions from taking place, so eventually the data stroage media will degrade.  Even if you put the DVD's in a perfectly insulated, lead-lined vaccum chamber you still can't prevent other risks like your house catching fire and all the data being lost.

I've just seen the last post you made.  This looks like a description of the penetration power of various different forms of radiation.  Yes, some forms of radiation will get through your cardboard box, like gamma rays and neutrinos.  Forrtunately, most of these will also go straight through your DVDs without changing them in any way.  However, it re-inforces the earlier point.  The only way to keep your data totally secure is to make back-ups AND preferably keep that data somewhere else (another house or stored "in the cloud" etc.)

SUMMARY:  Your boxes are OK.  The light-coloured reflective ones are better.  Keep them out of direct sunlight and keep them cool.  Backup your data frequently and keep the backup elsewhere for maximum security.

4 hours ago, studiot said:

Galaxies and Cosmology Jones and Lambourne (editors)   This is an OU set book

Thanks Studiot.  That looks like exactly the sort of thing that would be useful for the sort of distance learning I will be doing.

I seriously considered studying with the O.U. but at the current time they seem to offer only "Space Science and Technology" rather than "Astronomy" or "Astrophysics".  As far as I can tell their course has more emphasis on technology and project management than I may like.  However, borrowing the bits that are of interest from their reading list seems like an excellent idea and is exactly what I wanted.

As reagrds the fourth book, an introduction to general relativity, that sounds remarkable and I fear that I may be missing out by not purchasing it.   You make it sound like a great read but I was going to skip it for now, if only to keep the cost of my purchases down.  I've got Sean Caroll's book  "An introduction to General relativity: Spacetime and Geometry" which has serviced my curiosity for General Relativity so far and indeed it's the section on cosmology that made me think Astronomy might be worth studying.

Thanks for your time and attention and good luck to you.

Hi everyone.

Overview:  I'm old but still have an interest in learning stuff.  I was going to try and get on an undergraduate or post-graduate course in Astronomy or Astrophysics but circumstances have changed, people have become ill and I won't be doing any of that for... an unknown but long time.     So I'm just going to do some reading at home but it seems sensible to use an undergraduate or post-graduate degree as a basis to guide that reading.  A Google search for recommended reading lists from major universities offering a graduate or postgraduate course in Astrophysics or Astronomy has turned up very few results.  Can anyone suggest a book or two please?

I'll be grateful for any replies but here's two examples of short and amazingly useful replies:

1.   An introduction to Stuff,  by Ima Scientist        <--- Was recommended for our final year BSc Physics module in "Nebulous Things".

2.   Here's a picture of our recommended reading list from  ABC University  for the 1-year MSc in Astronomy  2009        [Picture attached].  Since it's 84 different books, I've underlined the half-dozen that most of us really made reguar use of.

4 hours ago, John Cuthber said:

Should the people who are most likely to come up with new ideas and discoveries be employed as scientists?

  Just my opinion:  There is no shortage of ideas.  Artist's frequently have the most incredible ideas and sometimes novelist's have an idea that changes the way an entire society see the world.  Surely, ideas are their primary currency but even in those fields people are initially recruited into the profession based on other skills they have.  Artists must be able to express their ideas in an artistic way, novellist's must be proficient in a language and then demonstrate an ability to communicate emotively despite the syntactic limits of that language.

   Most of the time a Scientist is not required to come up with fantastic new ideas, so it is reasonably natural to recruit people into the profession based on other skills they have.  It is still not difficult for most people to come up with new ideas when the need arises.   The difficulty lies in coming up with ideas that remain consistent with existing well-established principles across the field or at-least knowing when such principles must be in conflict and need challenging.  We are not born with the knowledge of Science so coming up with relevant good ideas absolutely demands that we have spent time studying the existing body of knowledge first.  Finally, few scientists are actually famous just for an idea they had, this is just a romantic view that we like to have and popular media propagates.  It is extremely likely that someone else realised that being in an accelerated box was similar to being in a gravitational field long before Einstein.  However, it was only Einstein that developed the idea with sufficient mathematical formalism.  Einstein is not famous just for the idea, he is famous for the development of that idea.

    As for the second part of your sentence, should scientists be people most likely to make new discoveries - that is more sensible then just searching for creative, imaginative people but is still not essential.  A person who can communicate scientific ideas to non-specialists, like some popular science documentary presenters I could mention, is still a valuable scientist.  A school Chemistry teacher, who motivates an interest in their pupils is still a valuable scientist.  An engineer who applies only existing theory to develop a zero-emission vehicle is a valuable scientist.  The scientists and technicians who developed and manufactured a vaccine for Covid-19 are remarkable (by comparison, developing a new theory of gravity seems less remarkable, if I'm quite honest with you).  I think it just depends on your idea of what science is.  It almost certainly isn't the romantic view of theoretical physicists coming up with new fantastic ideas anymore then most experiences of a real-life spy are like the tales told of James Bond by the novelist Ian Fleming.

   Science is an expression of human curiosity and sometimes a tool to help mankind influence the environment in which they find themselves.  It is made possible by the hard work of farmers and factory workers that sustain the scientists while they develop ideas or apply existing theory.  Recruiting new scientists on the basis of identifying who can feed-back the most benefit to the rest of society is as sensible a recruitment criteria as any.  There is no shortage of new, fantastic ideas at the current time.

1 hour ago, Alex Mercer said:

What comes of discussing physics if you are simply a member of the general public and not a professional scientist/physicist?

    Hopefully, you enjoy yourself and understand something better.  I'm just going to focus on the use of this forum.  Others have spoken in more general terms about the history of developments in Physics.

What's the point of the general public discussing (and replying to) ideas in this forum?

1.  It may be that you realise why things can't be the way you thought - but that is not to be thought of as a negative thing ("oh, I was wrong").   It is progress and development in your understanding.

2.  It may be a practical benefit.  For example, getting the right temperature of light bulb to make the kitchen look clean.

3.  Very occasionally, you get to help someone else and that may be worth doing.

Very, very rarely will it achieve a revolution or significant change of thinking in the scientific community, if that's what you were looking for.  Presenting an idea in this forum is not likely to be a shortcut to publishing a research paper in a recognised journal.

If you think of this site as being a discussion forum for the benefit and betterment of the users, that would be best and hopefully it will be enough to make it worthwhile.  Shrug off some of the replies if you need to, there are always people with their own agenda and motives just like any online activity these days.

But what do I know?  I'm quite new here and I've only done a quick survey of the site similar to yourself.