21

Physiology & Medicine / What are the harmful effects of Vaping?

« on: 21/09/2021 15:34:47 »

Hi all,

    Is there any research on the harmful effects of "Vaping" (using electronic cigarettes) compared to old fashioned tobacco smoking?
    Anyone have a brief summary?   Do we know if it increases cancer risks, risks of COPD or anything else?

Best Wishes.

22

Radio Show & Podcast Feedback / What happens to light's lost energy?

« on: 14/09/2021 12:19:42 »

What hapens to light's lost energy?
  Podcast available on 13 Sept.  2021.

Some feedback and comments were made here:  https://www.thenakedscientists.com/forum/index.php?topic=83011.msg654459#msg654459

23

Physics, Astronomy & Cosmology / Lagrangian Mechanics - Why is Nature lazy?

« on: 01/09/2021 23:21:42 »

Hi everyone.

   What proof or good reason exists for suggesting that all physical systems that we might want to study can be modeled with a Lagrangian and a least action principle?

  I honestly don't know.  Why is Nature lazy and always trying to minimise an action?

Biologists and Chemists welcome - please check this and comment if it's wrong:
    Chemists and Biologists don't seem to assume that every system they want to study and model can be represented with a Lagrangian.   I'm fairly sure that when a vaccine for Covid was developed no one started by proposing a new Lagrangian for the system.

Best Wishes.

24

Radio Show & Podcast Feedback / Can 2 light rays collide - podcast available 28/08/21

« on: 30/08/2021 01:22:41 »

Hi.
   Thanks for another podcast. 

What was Good?     Interaction with a school.

What was worrying?   How do you decide where to stop an answer and how much to simplify?
   Let's ignore some of the advanced topics, they need simplification.  However, the question about circles could have been answered differently and probably wouldn't have confused too many children.
Perfect circles do not exist in reality, only in abstract geometry.  They know this, children have used a compass and they know that no matter how careful you are, it never quite works.

Best Wishes.

25

New Theories / Is Non-standard Analysis superior to conventional Real Analysis?

« on: 27/08/2021 17:19:20 »

Hi.

    Calculus  ----> 

You've seen this stuff.  It involves small changes in y  divided by the corresponding small change in x.
You were probably taught Calculus in school with this concept.
Some time later there was a procedure to formally consider Limits.   You may have seen the ε , N  definition for limits.

   The thing is, why didn't we just stick with the intuitive idea of infinitesimals?

Disclaimer    This is not a new theory, it's an old theory.  It's also not mine.  It's not even all that new to suggest that we should teach Calculus with Non-standard Anlaysis.  However, there isn't an "old theory but ready for revival" section in this forum so I've placed the thread here. 

References
    If you have a week to spare:
    H. Jerome Keisler -  Foundations of infinitessimal calculus.
    Otherwise, use Wikipedia with  "hyperreal number"    and   "Nonstandard Analysis"  as search terms.   

New Theory    Should we teach Calculus with Nonstandard Analysis?
   (I know it's traditional to add a 20-page document to a New Theories post, so I've written something at the bottom of the post).
 
- - - - - - - -
Attached file:     NonStandard-thinking.zip               [Downloaded  0 times].     

26

Physics, Astronomy & Cosmology / Where is the gravitational potential energy? School-level question.

« on: 14/08/2021 02:01:38 »

Hi everyone.
   This section of the forum has gone a bit quiet as of late.  Here's a question that should be open to everyone who has studied Physics at school level.  I'm interested in all answers and opinions.  You can talk about what you know from University if you wish but the main focus (for me) is on what I can say or present to a school-age audience.   What is the best way to answer questions like this from a child in school?

Background     When you were at school you may have studied some Physics.  How were you taught about gravitational potential energy?   Did it seem sensible to you?   You may have seen examples like the following:

    /\
 /  || \@
/   ||  \
    ||
 This thing is a tree.

@  <--- This thing is an apple in the tree.

What follows next is a beautifully animated diagram of the apple falling from the tree and gaining kinetic energy as it falls....
(You just have to imagine that part).

   It would have been said that the apple had gravitational potential energy while it was up high.  This potential is converted to kinetic energy as it falls.     OK, remember that?
   - - - - - -
Questions to focus on:
(i)  Were you taught that the gravitational potential energy was  IN THE APPLE ?
(ii)  Did you believe it?   (I did while I was at school).
(iii) Was there anything different about the apple when it was up high or just that it was up high?
(iv) If the energy was in the apple, then did it have more mass when it was up high?
(v)  You may have studied more physics since school.  Where do you now think the gravitational potential energy is located?
(vi) How would you go about explaining this concept to a school-age student, maybe one of your own children if you have them?  Suppose they ask directly   "where is the gravitational potential energy stored?"  - what will you tell them?

Thanks for your thoughts and opinions.  Best Wishes to everyone.

27

Just Chat! / Technical problem with this website.

« on: 09/08/2021 14:00:37 »

Hi.

I'm hoping to get some technical advice.
I've saved some drafts of posts I was writing.   I now want to clean up, delete some of those drafts and possibly finish a few others and post them.
What happens if some of the original posts have been moved or merged since the drafts were created?   Specifically, some of the original posts have been moved by moderators to other sections.   Would the drafts somehow find their way to the new locations?

This is not too important and I may just end up deleting all the old rubbish anyway.
Best Wishes.

28

Radio Show & Podcast Feedback / "Space Oddity" podcast circa. 27/07/2021

« on: 27/07/2021 00:13:50 »

Hi.

This was a good discussion.   Thank you.

29

Just Chat! / Not so good YT videos.

« on: 25/07/2021 23:40:10 »

Candidate 1:     "Science Time" .      Overall impression  4/10.

     Not sure If we can really talk about good videos we would recommend.  That might be unfair advertsing.
However, I'm fairly sure we can talk about YT videos we wouldn't recommend.

"Science Time"  keeps coming up in the automatic recommendations of my YT experiences.
I've seen only a couple of these.  They "claim" to be discussing  a topic "with a famous scientist" but they always seem to be talking about a topic and then mixing in some pre-recorded speech from that scientist.  I've never seen the scientist in the video only ever heard their voice.   Sometimes the audio quality is very poor and not at all indicative that the scientist went to a sound studio to record this for Science Time
     To complement their audio,  Science Time show a collection of images on the screen which really are very pretty but often have very little to do with the conversation.
      They choose topics that are obviously interesting to the general public but after wasting 12 minutes of your life, you will leave feeling that you have barely learnt anything and spend the rest of day trying to remember where you heard that speech or presentation before.
     Somehow they have 190k+ subscribers.
 
Am I missing something here?  Is Science Time just as interesting as the stuff they call "musak" and play in the lift ("lift" = "elevator" in some countries)?
   Comments welcome.    Has anyone watched more of their videos and do they get better?

30

Just Chat! / Quality of discussions

« on: 21/07/2021 00:11:57 »

Hi.

What has happened to the quality of discussions on this forum?
On a quiet evening we used to be able to read and possibly get involved in some interesting discussions.
   At the moment there are perhaps half-a-dozen people using the forum like some sort of mud slinging contest on some social media site.  Please don't do this, the only people who care are the people you wouldn't want to be engaging in discussion with anyway.

   I'm not certain what this forum can offer but there are a few things that it can not offer:
1.  You probably can't change the world here and I'm not sure that you should try.
This forum is interested in promoting free science, and there are other places that are better suited for testing the limits of free speech.         [Taken from the Acceptable Usage Policy, https://www.thenakedscientists.com/forum/index.php?topic=8535.0]

2.  You are asked to keep discussion friendly and defuse rather than escalate a situation:
If you feel another forum user is using insulting language, seek to calm things down, or if that fails, report the matter to the moderators.  Under no circumstances should you seek to trade insults, or make accusatory remarks to that, or any other, forum user.    [Also from the A.U.P., link given above]

3.  This forum is not a shortcut to publishing a paper in a recognised journal.  No one cares if you are the king of this hill because this is not a very important hill anyway.   Apologies to the owners and management of this site:  I like the website but in all fairness, professionals don't usually check these forum posts in the Monday morning staff meeting.


What does or should this forum offer?
   Well that might be worth some discussion here.   
One answer I had from a moderator some time ago was essentially  "I still don't know"  (I can't find the link to that now, sorry).
    Maybe some other users would like to see a "homework help" section?
    Some people just like the radio show or podcast and want to ask more questions or get more involved.
    Maybe some users would like to see a Philosophy and Theology section added.
    Why are you here now?  What would like to see here?  What would you like to take away from your time on the site?

Best wishes to everyone.

31

Chemistry / Can Sodium react with water when there is a distance between the two?

« on: 18/07/2021 18:31:38 »

Hi.

 Na(s)  +   H₂O (l)  →    Na(OH) (aq.)   +  H₂  (↑)

   Or something similar happens when  solid sodium is carefully put into contact with some liquid water at  room temp & pressure.

   Now does the sodium atom really need to be in such close proximity to water?    The sodium atom tends to form an ion and the reasonably free electron would seem to be able to travel a bit.   How far away can the sodium be kept from the water and still have the reaction proceed?  Do they need to be within a few Angstroms of each other or are we taking about something like a millimetre or more?  (You know my follow up question will be:  Accepting that the reaction rate may be small can we have them one full metre apart  etc.)
    Water vapour in the air might be an issue,  let's say we do the experiment in unsatuared air.  Perhaps we could put the experiment in a partial vaccum maintained by a pump and keep the liquid water temperature low so that it doesn't tend to vaporise.

32

Geek Speak / Windows 11

« on: 07/07/2021 09:28:00 »

Hi.

I'm seeing adverts for windows 11.
Any geeks have anything interesting to say about it?   Is it going to be faster, more secure or just bloated with extra junk?

You don't have to spend too long answering  (after all I'm too lazy to read anything about Windows 11 myself).

Best wishes to all.

33

Geek Speak / Recent windows update has a weather warning on the task bar

« on: 17/06/2021 17:29:35 »

Hi.
I hope everyone is well.
So, there's been a recent windows update and now my OS boots up with an extra piece of trashy information in the right hand side of the task bar.
   It tells me if it's day or night and if it's raining or not.  This could be very useful if I lived in a basement flat without any windows but I don't.
   I can only imagine this new app is eating up some CPU clock cycles and some available RAM.  It's also getting new data from somewhere so I guess it's eating into my internet bandwidth. 
    It seems like a pointless waste of resources.   What's the fastest way to turn this off please?   Obviously I want it thoroughly disabled not just made invisible - I want my resources back.

Thanks.

34

Just Chat! / Mathematics is a decent science.

« on: 17/06/2021 00:04:16 »

Hi.

   Why do you (Nakedscientists) have a thousand sections for life sciences (that was just a rough count) and not one section for Mathematics?  Mathematics is everywhere but life sciences are only useful in a small number of real world situations.
   Let's say Jane went shopping and picked up a thing that required her to evaluate an integral over a closed path on the complex plane.  Alternatively consider John, who was out walking in the sunshine when he had a need to generate an infinite sequence of numbers that are co-prime but not primes.    Where are these people going to get help with their serious problems?

35

Physics, Astronomy & Cosmology / Another Relativity paradox

« on: 07/06/2021 16:32:17 »

Hi all.

   Does anyone have some knowledge or insight about this "paradox" in the theory of Relativity?

   Imagine a submarine underwater.
Initially:
The submarine is at rest relative to the fluid and has adjusted it's tanks so that it has equal density with the fluid and remains at a depth of 100 metres.  (No thrust required from the engines, it just has neutral buoyancy).
 
Subsequently
    The submarine accelerates rapidly to reach relativistic speeds (let's say 0.9 c) relative to the fluid and then sustains a constant velocity.  This is intended to be a horizontal motion, the fins, bow planes etc. were not set to drive the submarine up or down.

Finally
     As is usual for these sorts of paradoxes,  we have two observers in two different frames of reference.

The submarine commander is at rest inside the submarine.  She should observe length contraction for the fluid in her rest frame and a corresponding increase in density of the fluid.  The submarine retains it's rest characteristics, including density in her frame.

A mermaid is at rest on the ocean floor.  In her rest frame, the density of the fluid has not changed,  however the submarine has undergone length contraction in her frame and it's density has increased.

Question
   Will the submarine rise or sink due to buoyancy?

Background info:   You may like to read the Wikipedia article about Supplee's paradox.
https://en.wikipedia.org/wiki/Supplee%27s_paradox
There is also a similar discussion about a Helium balloon moving through air on another forum.  (I'm not sure I should put links to another forum).

   I do not know the answer.  I can see references to articles in that Wikipedia entry but they seem to demand some application of General Relativity and a complete re-write of the Archimedian principle.  I was wondering if there is a resolution based only on Special Relativity - but I'll take any insight or discussion I can get.

36

Plant Sciences, Zoology & Evolution / How can I keep my grass short?

« on: 31/05/2021 17:39:18 »

Hi all.

   Do you want to save mankind from something terrible and prove to everyone that Biology is a worthwhile science?

    What substance, system, method, plan or procedure exists that can reduce the number of times a person needs to cut their grass?  Please.  I never want to do this again.

    Design requirements:
     I know I could rip up all the grass and put down stone.  Your suggestions must be better than this.
1.  I want to keep some living grass.
2.  It can't take longer to follow your procedure(s) than it would to just cut the grass.

37

Physics, Astronomy & Cosmology / Problems with PopSci articles in GR. Should we stop using one example?

« on: 17/05/2021 19:17:25 »

Hi everyone.

   This is not meant to be a monologue about what I think.  I'm interested in discussion.   If there is a personal objective for this thread, then it is to try and persuade people to stop using certain phrases and/or certain PopSci ideas in the teaching of General relativity.

Background:
   General relativity (GR) differs from Newtonian models of gravity in many ways.  It is commonly stated that Newtonian models assume instantaneous action at a distance and imply infinite propagation speeds for the effects of gravity. ^{(References stripped out, I'm already boring the audience but you can challenge any statements made if you wish).}   We acknowledge that some sources (sources of information not sources of gravity) only require very high speeds of propagation for Newtonian gravity but these speeds are still far above the speed of light.^{[reference stripped out]}

   In contrast, GR is frequently associated with a finite speed for the propagation of gravity through space.  This may be called the "speed of gravity" in many PopSci articles and it is also frequently claimed to be identical to the speed of light.  (I would contest some of those statements - but this is what the popular media says).

   Here is a (non-exhaustive) list of articles that compare GR and Newtonian gravity by discussing a sudden disappearance of the sun and how this would affect the orbit of Earth:

   i.   What is the speed of gravity?,  Ethan Siegel, 2014, available on-line at:
https://medium.com/starts-with-a-bang/what-is-the-speed-of-gravity-8ada2eb08430

   ii.  If the Sun suddenly disappeared, it would take about eight minutes for Earth to become dark (due to the speed of light). How long would it take to feel the absence of the Sun's gravity?,   Astronomy magazine, 2012
https://astronomy.com/magazine/ask-astro/2012/05/gravity---the-traveler

  iii.  Here's what would happen if the sun disappeared right now,  Business insider, 2015.
https://www.businessinsider.com/what-would-happen-if-the-sun-disappeared-2015-8?r=US&IR=T

   Item (i) above is relevant because it has been recommended by this forum.  Item (ii) is shown because Astronomy magazine is a well known and respected magazine for people with an interest in Astronomy.   Item (iii) was chosen because we wish to indicate that the discussion is not limited to places that just specialise in science.   As previously mentioned, it is a non-exhaustive list and we believe this example (the sudden disappearance of the sun and the affect on Earth's orbit) is widespread among the popular media and used to illustrate a difference between GR and Newtonian gravity.

   We could produce similar lists of where such questions have been asked and answered online.  Google will bring a list of such instances involving well known Q&A sites like Quora,  Physics Stack Exchange,   and various online science forums.  However, we've already bored the audience enough.
                  - - - - - - - - - -  End of background   - - - - -

Questions and discussion requests:
1.      Have you encountered a similar example being used in your own learning?
2.      Please take a moment to think about and answer the question that features in this example:   How long would it take the earth's orbit to be affected by a sudden disappearance of the sun?   If you are familiar with GR, can you use it to answer the question?
3.      This is a quote from the article that has been recommended to others by this forum:
" But what about gravity, and the earth's orbit? ...... Believe it or not, this is one of the most severe differences between Newton's old school theory of gravity and Einstein's General Relativity".   We propose that GR can produce more than one answer to the way in which the orbit is affected and hence more than one answer about the speed at which the change in gravitational effects would propagate (including no answer at all).   This example should simply be avoided in all teaching about GR and never be described as an important feature.  I can't believe how widespread this example has become in teaching.   But what do you think?

38

Just Chat! / What useful things can be done in a forum post?

« on: 04/05/2021 22:32:12 »

Hi. I'm a newbie here just trying to learn what can and can't be done.

What useful things can be put into a forum post?   I saw a post in the Feedback section about LaTeX.... I'm just going to try some of that out first.



Hopefully that will work.

Questions:     
      1.  Can I preview a post?  I've clicked the preview button at the bottom right and nothing happened.
      2.   Can I insert a small picture in-line with the text,  or do all attachments and insertions just get dumped at the bottom of the post?

Thanks and best wishes to all.