saac

On 02/04/2021 at 15:11, ollypenrice said:

One defining characteristic of terrestrial life is predation. It vastly increases (and affects the nature of) competition between species. I wonder if there might be alien ecosystems without predation? It would be nice if there were. I have this notion for a short story in which passing alien spacecraft fire off the odd missile at the predatory Earth in the way that 18th century navigators would blast off the odd disapproving cannonball in the direction of cannibal islands...

Olly

Like typical predators we have chased many rabbits down many holes here  but we haven't properly responded to Olly's original post!  Is it likely that alien ecosystems could arise without predation?  

Jim

3 hours ago, andrew s said:

So is a repeat of a live feed chewing the cud or an over long SGL thread? 

Regards Andrew 

rumination , fun activity for cloudy nights !

6 minutes ago, JamesF said:

Perhaps "evolutionary pressure" is tantamount to a tautology.  If there is pressure, evolution is the result?

James

I think you may be right James. It's all chance , toss enough coins and it's inevitable a favourable combination will appear.  I think evolution and life are two sides of the same coin.

Jim 

52 minutes ago, andrew s said:

You could imagine stimulating an environment with no limitations of any of the requirements for life. Energy in a low entropy state, materials etc. and a set of  mutating reproducing organisms. They would just grow exponentially with no evolutionary pressure so predation would not have any obvious advantage.

Not very interesting, so say one or more constraints were added then a limit would be reached. However, now any organisms that evolved a way of extracting the limiting resources from another organisms would be at an advantage . Predation would be an advantage.

Regards Andrew 

I think the interesting point there Andrew is containment of the condition "no evolutionary pressure".  With evolution resulting from and then exploiting mistakes in the duplication process  I would argue that evolution is inevitable. Then follows predation which as you said would be an advantage.   It would be interesting to find out if there are any biomes where predation is not present; most likely extremophiles  I guess.

Jim 

11 minutes ago, andrew s said:

 

What makes predation advantageous is that it provides a concentrated source of low entropy. 

Regards Andrew 

And "life" would seem to be programmed to exploit that concentration .  Which makes me wonder if predation would be inevitable even in an environment with surfeit energy. 

15 minutes ago, Tiny Clanger said:

Energy is plentiful, but the trick is converting that energy efficiently to something you can use . I've no time to check this (things to do, people to annoy) but I seem to recall the conversion rate for sunlight to energy in green plants is below 10%.

I may have mentioned this in a different thread but there is a lovely BBC Horizon documentary by Jim Al Khalili in which he shows how the surprisingly low efficiency of photosynthesis is made viable by quantum effects within the delivery mechanism of the photon to the site of photosynthesis.  It's one of a number of examples he presents which show quantum effects in living organisms. 

Jim

5 minutes ago, ollypenrice said:

Yes, but consider two environments with the potential for life. One is like ours, with a limited energy source and another with an abundant one. We tend to be locked into the notion of competition for limited energy. What if it were pentiful?

Missionaries in the south seas were utterly exasperated to find themselves among people who had no work ethic because they didn't need one...

Olly

That's what I was hinting at Olly; I agree, energy would need to be plentiful. In fact there would have to be a surfeit of energy to avoid the evolutionary advantage of  predating on a life that had concentrated the energy for you.   Would not that temptation arise though either by wilful action or accident !  Evolution is afterall a series of useful accidents.   As soon as there is a shortcut to gaining more energy for less effort then evolution is back in the driving seat and we are back to predation. 

 Those missionaries remind me of a Calvin and Hobbes on the much maligned art of indolence.

Jim 

18 minutes ago, ollypenrice said:

This is an analysis of what happens here and I fully accept it. My own knowledge of these processes lags far behind yours. What I'm trying to do, though, is identify those processes which do not have to apply universally even though they happen to apply here.  Terrestrial evolution has been driven in a competitive environment but it strikes me as possible that there might be non-competitive environments which would still lead to intelligence of some sort. I'm minded of Percival Lowell who was persuaded that his non-existent Martians were right wing Republicans because only that political model could organize the global construction of non-existent canals.  I would want to avoid falling into such notions!!

Olly

I guess a world where life never evolved further beyond green plants would be devoid of predation. The only thing eaten  would be photons. Could plants have evolved through without first going through the evolutionary stage of microorganisms (bacteria etc) which, I think, some are predators (not really sure though).   I suppose the need for predation comes down to the availability of energy and resources - if these are readily available elsewhere requiring less risk and energy expenditure then why bother eating !  The moment eating though delivers more energy, then the evolutionary blue touch paper is lit again and we are back to making predators.  As energy is concentrated in each organism , then  I wonder that this route is almost a certainty. 

Jim 

1 hour ago, Tiny Clanger said:

I read that.and thought the film would be about The Leakey's exploits in uncovering fossils ! It seems not 😉

There is a line given to a character in Babylon 5 by J.M Straczynski ( a perhaps surprisingly philosophical show considering the general shallowness of TV SF) which makes perfect sense to me :

'We are the universe made manifest, trying to figure itself out.'

Yep the movie Lucy itself was a bit disappointing.  I used to like Babylon 5 but then it just seemed to disappear from the TV;  was it cancelled perhaps?   The quote echos Carl Sagan's "The cosmos is within us. We are made of star-stuff. We are a way for the universe to know itself.”   Im going to argue against myself now    In my previous post I suggested that the universe does not know or care about us.  It's funny but we have a tendency to see ourselves as separate from the universe (nature) when the truth is we are very much part of it , no less than any mighty star or galaxy. We are undeniably of this universe . Maybe Sagan and Babylon 5 then were not that far of the mark - we are the universe's attempt at figuring itself out !  My God, it's a teenager and we are its angst !  

Sci fi movie recommendation - found on Amazon the other day on Amazon Prime Video   "Archive" - it's an AI  theme . I thought it was quite good. 

Jim 

3 minutes ago, Corncrake said:

This is curious, I dont often think of the word "manifest" but this is the second time today !

The first time was when @ollypenrice posted his picture of (un)intelligence, I thought then "Heironymus is made manifest "

 

Must be a ripple in the "matrix " somewhere  

There is a line in the movie Lucy which caught my imagination. It's by Morgan Freeman's character , a professor in Biology,  commenting on the problem of life and how organisms come up with different solutions he says words to the effect "if the environment is forgiving organisms will chose to pass on their DNA through reproduction, where the environment is unforgiving organisms chose to be immortal" .  Later on David Attenborough would introduce me to creatures like star fish which  clone themselves  effectively being immortal.  Then I came across the "immortal" HeLa cells  and the story of Henrietta Lacks - a truly fascinating story .  The biology of life is utterly amazing and as complicated if not more so than anything in the physical word.  And all the while we life in a universe which as far as we are aware does not know of us nor needs us !

https://en.wikipedia.org/wiki/Henrietta_Lacks

Jim 

1 minute ago, saac said:

Predation - just another way of balancing the entropy equation - life is about postponing the inevitable destination of disorder. We are not meant to be here   

Jim 

Duplicated post - sorry - editing got me tangled up   

Jim 

15 hours ago, Paul M said:

Let's hope it falls on deaf ears. Aldebrians might mistake it as an act of war...

 Well if they don't they certainly will when Easter Enders arrives a few year later

Hey just a thought,  could our extraneous radio and TV signals  be considered electromagnetic pollution . Humans what are we like . 

13 hours ago, Paul M said:

The first episode of Coronation St. is only 5 years away from Aldebaran.

 

The poor sods they have years of watching ahead of them  - mercy, 

Jim 

Tx corncrake, Level 5 seems to ring a bell - I remember reading an explanation in a book somewhere what it actually translated to in terms of getting the same result in successive coin tosses. Some googling required I think.   

So Sigma 3 is the confidence level am I right .  Does anybody know off the  top of their head exactly what that means in terms of successful coin tosses.  Also what confidence level did they declare for the Higgs Bozon - was it 6  - I  can't remember . 🙄 

Jim 

5 hours ago, Corncrake said:

Yes!,
I noted that also when I read it on the CERN site.
There are from time to time many ",,, is this maybe new that points to beyond the Standard Model ,,,,"  at 3sig this one may stand out from the herd ?

Guess what , I was amazed when swmbo came in saying "did you know about,, ", as I was typing the above bit,
(she watches TV !)  and so it has made it onto the Beeb news !
https://www.bbc.co.uk/news/science-environment-56491033

 

Exciting stuff.  Curious how the reporter styled it "Physicists have uncovered a potential flaw in a theory that explains how the building blocks of the Universe behave."

Why is it a "flaw" and not "an previously unknown level of detail"  because that what it truly is.  Theories by their nature do not describe nature - they describe our present understanding of nature and as our understanding improves the theory advances. Grrr Arghhhh .  

Jim 

I can't comment on your design but you may find this site helpful; it offers some useful resources including some a free web based analyser where you can upload and share your spectra. 

https://publiclab.org/wiki/economist

Jim 

In theory it would seem so. To be pedantic for a second though , matter does not have gravity - matter deforms spacetime and it's the curvature of spacetime which we know as a gravitational field.  To paraphrase Einstein, spacetime tells matter how to move while matter tells spacetime how to curve.  There is a thought that "dark matter"  - if it does exist  - may  bend spacetime in the opposite way to normal matter -  in effect creating a repulsive field rather than an attractive gravitational field that we are familiar with .   So instead of forming valleys in spacetime it would form hills and mountains.  Gravitational lensing due to dark matter I think, and I may well be wrong here , is already incorporated in our conventional understanding of gravitational lensing by massive objects.  

https://www.nasa.gov/content/discoveries-highlights-shining-a-light-on-dark-matter

Jim 

Polemaster to date has been the piece of kit that still puts a smile on my face whenever I use it- really worth it. Of course similar can be achieved with Sharpcap and suitable camera.   I've recently placed an order with FLO for the Asair Pro - I wanted something that was easy to use and didn't suffer from skill fade.  From what I could see from the various reviews it looks like a useful bit of kit.  What about software - PixInsight ?   I think my next major purchase will need to be something to take me into the mobile , grab and go world.    I would love to get into Night Vision or maybe a nice spectroscope but that will need to wait until retirement  

Jim 

3 hours ago, Andy ES said:

Thanks very much for the detailed description, glad it worked.

ill print this off and use it on mine in 2040! 😁

 

thanks

Alexa, set reminder,,,, 20 years  

Jim  

1 hour ago, andrew s said:

Cats are far too sensible. Regards Andrew 

That me laugh Andrew.  I'm well and truly in the dog camp (2 year old westie)  but I agree wholeheartedly with that -  there is no counter argument there.  

Jim 

The David Kriege/Richard Berry  book have for a 25 inch mirror -  side bearing 32 inch diameter and 1 5/8 th thickness (41 mm),  rocker box  1 1/2 inch ( 38mm).   So that agrees well with faulksy's dims.   

For my 16 inch  Dob the bearing on the rocker box  is effectively the thickness of the sheet so 28 mm.  The actual side bearings are formed by a 28 mm sheet sandwiched between two other sheets - so I guess the actual bearing is again 28 mm thick .  My bearing and rocker box was a bit unconventional inspired by  Gordon Waite's design (http://www.waiteresearch.com/index.php/about/)   so my bearings dimensions were very much  "if it looked right , then it should be ok"  

Jim 

Just to echo what faulsky said above regarding good quality ply. If you do decide to go  for  Birch ply try to source the top quality stuff, here in UK I think BB grade.  The lower grade ply that typically sells in DIY chain stores should be avoided as the finished layers are never as good and the sheets may also contain a high number of voids.   The sheets that I sourced from my local timber specialist were supplied in 1.6 by 2.2 m I think .  I can confirm the grade if it is any use to you but off the top of my head I think it was BB. 

https://www.woodworkerssource.com/blog/woodworking-101/tips-tricks/your-ultimate-guide-to-baltic-birch-plywood-why-its-better-when-to-use-it/

Jim