Author Topic: Population decline  (Read 2132 times)

Offline andrewmc

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Re: Population decline
« Reply #50 on: July 16, 2020, 11:37:01 pm »
He also produced the only map to show the Earth as it really is, with no deformation anywhere. Strangely it never gets mentioned, probably as it has 'funny edges'. It's on my wall above my desk here:

It's still got distortion; it just attempts to minimise it. You could make a map with even less distortion by using more cuts.

It is impossible to accurately represent the surface of an oblate spheroid on a 2d plane.

Offline pwhole

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Re: Population decline
« Reply #51 on: July 16, 2020, 11:37:12 pm »
Well if you told someone in the Victorian era that in the future they'd be able to go on holiday anywhere in the world with a maximum of 24 hours travel time they'd also say pigs will fly. Or if you said you could build a skyscraper nearly a kilometre high they'd say you were a lunatic. But some of them rolled their sleeves up and got on with it, and here we are.

We can solve all those problems, like feeding all humans adequately, and living on our planet sustainably now - we just don't.

Offline pwhole

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Re: Population decline
« Reply #52 on: July 16, 2020, 11:42:12 pm »

It's still got distortion; it just attempts to minimise it. You could make a map with even less distortion by using more cuts.


It's less than one percent distortion though, and it's evenly spread across the whole surface, unlike other projections, as it's just the 'puffing up' of each triangular face to be spherical. The idea of the map being cut as it is was to show the entire earth's surface as one interconnected landmass, and more cuts would ruin the straight-line measurements (though the area between Japan and Australia is the compromise bit that doesn't work). But essentially you can draw a straight line between any two destinations and it will be the flight-path an airliner would take, as it's spherical.

Offline mikem

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Re: Population decline
« Reply #53 on: July 17, 2020, 06:54:11 pm »
Quite a number of species go through boom & bust lifestyles, the most notable being lemmings & locusts.

Online andybrooks

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Re: Population decline
« Reply #54 on: July 17, 2020, 07:33:20 pm »
I'm surprised to learn that a flight from Perth (Australia) to Buenos Aires would want to go via the North Pole.

Offline pwhole

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Re: Population decline
« Reply #55 on: July 18, 2020, 12:22:15 am »
It doesn't - it goes across the blank triangles at the bottom, and the edges all join up when made into a sphere. Clearly this is all too much for some. Try Perth to London as that doesn't cross any triangles? Flight paths were just an example I used, not the main reason for the map's existence.

Offline Duck ditch

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Re: Population decline
« Reply #56 on: July 18, 2020, 06:51:45 am »
Hans Rosling shows a ray of hope on global population decline.  His TED talk is informative.

There is over 1000 billionaires in this world growing richer everyday.  When asked to pay more taxes when they reach more than 999million, they baulked . Instead they pay for political influence.   Greedy greedy greedy.   Take it off if they don’t fund green technology and development.

We will have vast wheat fields in Greenland and Antarctica before  terraforming Mars because it’s easier.  Meanwhile Bangladesh drowns and Africa bakes.  :wall:

Er right er,, is there a games room in this virtual club hut?

Offline pwhole

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Re: Population decline
« Reply #57 on: July 19, 2020, 11:08:27 pm »
The United Arab Emirates just successfully launched a mission to Mars from Japan - the first ever space trip from a Middle East country. They specifically referred in the broadcast to the need to move away from oil extraction and moving young people into space research technology for future careers:

https://www.bbc.co.uk/news/science-environment-53394737

Offline Duck ditch

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Re: Population decline
« Reply #58 on: July 20, 2020, 08:05:03 am »
I find space exploration interesting. International cooperation, sharing knowledge is successful in space.  Terraforming the moon and mars has to start with oxygen.  The moon is only about the size of Australia so perhaps trial it there.

However Antarctica has oxygen.  No international cooperation though. 

2095 billionaires according to Forbes.  99% tax after the first 500 million. Plough it into saving Earth. 

Online JoshW

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Re: Population decline
« Reply #59 on: July 20, 2020, 09:08:49 am »
An entirely different question, but there appear to be smart people in this thread.

How small would the diameter of a planet have to be, for us to recognise that it was spherical. to clarify, as Earth is so big, walking on flat surfaces feels like flat surfaces, how small would the planet have to be for it to feel like we were walking on a round thing?

Offline mikem

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Re: Population decline
« Reply #60 on: July 20, 2020, 09:27:37 am »
2095 billionaires according to Forbes.  99% tax after the first 500 million. Plough it into saving Earth.
Or lose all their tax as they move to a country that doesn't take it all away...

The moon isn't large enough to sustain an atmosphere, so can't be terraformed. & you can see the curvature of the earth from high points on our surface.

Offline ZombieCake

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Re: Population decline
« Reply #61 on: July 20, 2020, 09:59:09 am »
Lots of potential cave sites on Mars  https://blogs.scientificamerican.com/life-unbounded/the-1000-caves-of-mars/
Trouble is the way things seem to be going you'll need to get a lift on one of Elon Musk's space ships.

Offline pwhole

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Re: Population decline
« Reply #62 on: July 20, 2020, 11:26:29 am »
An entirely different question, but there appear to be smart people in this thread.

How small would the diameter of a planet have to be, for us to recognise that it was spherical. to clarify, as Earth is so big, walking on flat surfaces feels like flat surfaces, how small would the planet have to be for it to feel like we were walking on a round thing?

If you stand on the Hollywood Hills and look south you can see Los Angeles going over the horizon, it's that big ;)

All the astronauts that visited the moon stated that they could 'feel' the curvature difference immediately when they looked into the distance. There are a bunch of 360° panoramas that NASA produced by stitching prints together which are truly astonishing to look at. Each astronaut had a Hassleblad camera clamped to the their chests (first ever bodycam?) so they were quite easy to produce. As there's zero atmosphere, there are no depth cues from the haze, and so often they'd set off walking toward a large boulder and didn't get any closer! Then realised it was ten times bigger than they thought and ten times further away, so gave up - until they took the Lunar Rover with them on later trips and could drive over.

Michael Light's book 'Full Moon' has some very large fold outs of these panoramas and it's well worth getting - there's a 'pocket' sized version, but you really need the sofa-size version to truly appreciate their majesty ;)

http://www.michaellight.net/fm-intro

Aha! Here: http://moonpans.com/vr/

Online JoshW

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Re: Population decline
« Reply #63 on: July 20, 2020, 11:31:31 am »
2095 billionaires according to Forbes.  99% tax after the first 500 million. Plough it into saving Earth.
Or lose all their tax as they move to a country that doesn't take it all away...

The moon isn't large enough to sustain an atmosphere, so can't be terraformed. & you can see the curvature of the earth from high points on our surface.

I guess my question was less about the curvature of the earth, and more about the actual sensation of being on a sphere, although I suppose the visual cues of the horizon seeming much lower (?) would contribute to that sensation.

Offline pwhole

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Re: Population decline
« Reply #64 on: July 20, 2020, 11:33:07 am »
Well in that case you need these guys ;)


Offline Chocolate fireguard

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Re: Population decline
« Reply #65 on: July 20, 2020, 01:21:14 pm »
The moon isn't large enough to sustain an atmosphere, so can't be terraformed.

It's not a matter of size, it's to do with the Moon's temperature and its escape speed.

There's a decent article here
https://en.wikipedia.org/wiki/Atmospheric_escape
in which the first section (on Jeans Escape) and the graph on the right explain things quite well.
It constantly refers to escape speed as escape velocity, but nobody's perfect.

Offline andrewmc

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Re: Population decline
« Reply #66 on: July 20, 2020, 01:28:32 pm »
You could terraform the Moon, you'd just have to put a lid on it :p

Offline langcliffe

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Re: Population decline
« Reply #67 on: July 20, 2020, 01:37:50 pm »
You could terraform the Moon, you'd just have to put a lid on it :p

Or dig a big hole and fill it with gravitons...

Offline mikem

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Re: Population decline
« Reply #68 on: July 20, 2020, 02:17:50 pm »
You'd still have to cope with 2 (earth) weeks of daylight (surface temp around +100'C) & 2 weeks of darkness (down to -173'C).

& your "roof" would have to be designed to absorb debris impacts that the earth's atmosphere normally deals with.

Offline crickleymal

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Re: Population decline
« Reply #69 on: July 20, 2020, 04:08:55 pm »
Quote
It constantly refers to escape speed as escape velocity, but nobody's perfect.
I always thought it was escape velocity. I'm fairly sure that was what it was called when I did physics A level
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Online JoshW

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Re: Population decline
« Reply #70 on: July 20, 2020, 04:16:00 pm »
Quote
It constantly refers to escape speed as escape velocity, but nobody's perfect.
I always thought it was escape velocity. I'm fairly sure that was what it was called when I did physics A level

As it would have a related direction, it's definitely velocity rather than speed.

Offline Chocolate fireguard

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Re: Population decline
« Reply #71 on: July 20, 2020, 04:37:40 pm »
Quote
It constantly refers to escape speed as escape velocity, but nobody's perfect.
I always thought it was escape velocity. I'm fairly sure that was what it was called when I did physics A level
I dare say it's still called that by some physics teachers and in some physics text books but:
1 if you call something a velocity you have to include a direction (they never do)
2 the direction doesn't matter - ignoring air resistance, or on a planet with no atmosphere, you could "throw" it at escape speed in any direction from vertical to tangential to the surface and it would escape.

In fact if you ignore the resistance of the planet (!) you could throw it downwards.

Online JoshW

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Re: Population decline
« Reply #72 on: July 20, 2020, 04:43:17 pm »
Quote
It constantly refers to escape speed as escape velocity, but nobody's perfect.
I always thought it was escape velocity. I'm fairly sure that was what it was called when I did physics A level
I dare say it's still called that by some physics teachers and in some physics text books but:
1 if you call something a velocity you have to include a direction (they never do)
2 the direction doesn't matter - ignoring air resistance, or on a planet with no atmosphere, you could "throw" it at escape speed in any direction from vertical to tangential to the surface and it would escape.

In fact if you ignore the resistance of the planet (!) you could throw it downwards.


Wait, mind blown.

So if I threw something at the escape velocity/speed at just above horizontal, it would escape the gravitational pull just as successfully as if I threw it perpendicular to the ground? Surely the speed required would be greater, as the vertical component would be lower otherwise.

Offline pwhole

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Re: Population decline
« Reply #73 on: July 20, 2020, 05:00:05 pm »
Isn't that just to compensate for air resistance normally? Why space rockets launch straight up instead of tangentially like planes, which need air resistance to fly? Or at least controlled resistance. If there's no atmosphere there's no friction, and so I don't think it matters what angle it goes off at as long as it can overcome gravity. I suspect the lunar modules blasted off back to the orbiter vertically simply to minimise the amount of propellant required.

Though that is a wonderful example of how little bang you need for your buck when there's no atmosphere and not much gravity - it's just a firecracker! ;)


Offline mikem

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Re: Population decline
« Reply #74 on: July 20, 2020, 05:05:42 pm »
As long as it didn't crash into the raised edge of an impact crater (although that might deflect it out into space). It depends if the gravitational pull is greater or less than the circumference of the atmosphere-free "planet".

 

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