Share this content
0
1083

I AM NOT DOUBTING THE EXISTENCE OF STARS

However...

Given the number of stars is immense and given they should all be getting some level of light to us, why doesn't the sky appear as a blanket of light at night?

Replies

Please login or register to join the discussion.

13th Jan 2019 23:24

Dark matter

Thanks (0)
14th Jan 2019 00:35

You are so correct. Take a sewing needle and stand outside on a starry, clear night. Start prodding the air around you. Every single pin prick you make you are stabbing at least one star, probably hundreds, thousands, even millions? For every point of the heavens there is at least one star.
In a universe that is steady state, the night would be brilliant white. But it is not. Most of the space is dark.
It is because of a phenomenon similar to the doppler effect but on light rather than sound waves. It also proves that the universe is expanding rather than contracting or staying the same.
As the stars/galaxies move away from us it stretches out the light waves during their journey to us, shifting them towards the red end of the spectrum. This then makes the light invisible to the human eye.
You would have to do some more research if you were really that interested, although I have a feeling you knew the answer before you posed it.
Now get a move on with your tax return deadline before your boss catches you day dreaming :-)

Thanks (5)
avatar
14th Jan 2019 07:22

Someone turns them off at night to save electricity? Or to let us all sleep?

Thanks (0)
14th Jan 2019 08:59

Well actually the sky does appear as a blanket of light, when you get away from human light sources and pollution.

Its quite hard to do in the UK however.

Thanks (1)
14th Jan 2019 09:05

It's partly because the light from the furthest parts of the universe is red-shifted so that it's now gamma rays or other wavelengths that aren't visible. The red-shift occurs (a bit like a passing ambulance siren) because of the speed the farthest parts of the universe are moving away from us.

Also, it's thought that light from the farthest reaches of the universe hasn't had time to reach us yet so the universe may be a lot bigger than we can currently detect.

Thanks (1)
14th Jan 2019 09:48

Quark, Strangeness and Charm.

Thanks (1)
to lionofludesch
14th Jan 2019 09:57

Post-Lemmy quaintness.

Thanks (0)
By DJKL
to lionofludesch
15th Jan 2019 10:23

A modern version of the Rice Krispie trio.

Thanks (0)
14th Jan 2019 11:20

Let me just say, I learned something new and genuinely interesting from this thread. Thank you guys!

Thanks (0)
avatar
14th Jan 2019 12:26

If you Google this question you'll see it's an ancient question and Stephen Hawking has given quite a decent explanation (as you would expect). My simple answer is that it would conflict with the law of conservation of energy if the whole night sky were entirely bright with stars due to the usual inverse power laws re light & distance etc.

A more sophisticated answer is that physical causality is Lorentz dependent (Einstein spotted that in his theory of Special Relativity as the only way for Maxwell's field equations to work for moving, non-accelerating observers) and that's why light has a speed limit in the 1st place, so parts of our universe will be forever hidden (beyond our light cone).

Thanks (0)
to Justin Bryant
14th Jan 2019 12:23

Justin Bryant wrote:
My simple answer is that it would conflict with the law of conservation of energy if the whole night sky were entirely bright with stars due to the usual inverse power laws re light & distance etc.

Well, that depends on whether you consider the universe to be infinite in size.

Actually, the fact that the sky is dark at night is good evidence that it is not.

Thanks (1)
avatar
to lionofludesch
14th Jan 2019 13:11

I don't accept that any physical thing can (by definition) be infinite (infinity is really just a mathematical concept that does not really apply to anything with physical reality). The universe is almost certainly finite (albeit ridiculously & unfathomably big), but there are almost certainly very many other (equally big if not bigger) universes.

If the universe were truly infinite then there would by definition be infinite copies of yourself having infinitely different lives (basically anything that was physically possible would have to happen; otherwise it wouldn't be truly infinite in the 1st place).

There would even be a world out there somewhere where Brexit has been solved without any problems whatsoever (possibly that alone disproves the existence of an infinite universe).

Thanks (0)
By DJKL
14th Jan 2019 12:24
Thanks (0)
14th Jan 2019 12:31

The simple answer is that it is a blanket of light, it's just some of the lights are brighter than others. The black bits aren't really black, there are no empty bits, just bits where the light is further away, and so dim.

If you're out at night in the dark you can still see where you're walking because there's a little light everywhere. Shine a torch right in your face and you can't see anything else. Stars work the same way.

Thanks (0)
to Duggimon
14th Jan 2019 12:59

No, that's not it, duggimon. If the universe were infinite, there'd be an infinite number of stars pumping out photons. So the dark sky proves that the universe isn't infinite.

DJKL's got the answer.

Thanks (1)
avatar
to lionofludesch
14th Jan 2019 13:13

That's rubbish. See above re light cones limiting your observation of an infinite (or at least very big) universe.

Thanks (0)
to Justin Bryant
14th Jan 2019 13:32

There'd still be an infinite number of stars within view.

Thanks (0)
14th Jan 2019 13:25

Clearly because we really live within a massive dome and the "stars" are merely light bulbs that have been put there to give the impression of a vast cosmos.

Thanks (0)
By DJKL
to Lone_Wolf
14th Jan 2019 16:09

I think that was one of the medieval interpretations, heaven was the bit above and the light from heaven shone through, obviously switching off the "power" to simulate night.

I vaguely recall some lectures touching on this belief when I was studying Chaucer in second year at university, it was all mixed up with courtly love, fabliaux and the rest, none of which I can now remember though I do still have a trick for Middle English- read it out loud with a Scottish cadence and it seems to make more sense and requires less checking re word meaning with the glossary.

Thanks (1)
avatar
to Lone_Wolf
15th Jan 2019 00:01

The Truman Show, Elton John, Chaucer, The Curious lncident of the Dog in the Night-Time, Olber, The Bible, The Matrix... just need a bit of Hendrix and/or Bowie and this could be the most diversely cultured Aweb thread ever.

Thanks (1)
By DJKL
to Tax Dragon
15th Jan 2019 10:42

I raise you Dante's Divine Comedy re earlier 14th century world view and here is your Bowie:

Didn't know what time it was and the lights were low
I leaned back on my radio
Some cat was layin' down some get it on rock 'n' roll, he said
Then the loud sound did seem to fade
Came back like a slow voice on a wave of phase haze
That weren't no D.J. that was hazy cosmic jive

There's a starman waiting in the sky
He'd like to come and meet us
But he thinks he'd blow our minds
There's a starman waiting in the sky
He's told us not to blow it
Cause he knows it's all worthwhile
He told me:

Thanks (1)
avatar
to DJKL
15th Jan 2019 18:20

He told you... there's no quoting Jimi:
https://youtu.be/vgyGJl_xm6o

Thanks (0)
14th Jan 2019 13:37

I belive HMRC are intending to resolve this as part of the MTD pilot

Thanks (4)
avatar
14th Jan 2019 13:38

It's like putting your coat on before you go out. The longer you have it on before you open the front door, the less benefit you get from it.

It's the same with light; the further it has to travel to illuminate somewhere, the less effective it is at illumination when it finally gets there. There even reaches a point that when light travels over a cetain distance, by the time it gets there, it really just can't be @r5ed.

Thanks (1)
to Vile Nortin Naipaan
14th Jan 2019 14:00

Jaysus !!©

Thanks (0)
14th Jan 2019 16:11

It's the Soviets fault.

Thanks (1)
avatar
14th Jan 2019 18:39

No-one would look up if the night sky was white. No-one would think "I wonder what's up there? Let's go and find out." The unbounded curiosity of humankind would have lost one of its most awe-inspiring avenues of expression.

In short, it does the soul good to look up.

God knows this, so He has arranged that the sky be full of black, yet also full of stuff that makes many of us wonder, some of us investigate and a few of us explore.

Thanks (0)
avatar
14th Jan 2019 18:41

OR their candles burned out long before
their legend ever did.

Thanks (2)
avatar
14th Jan 2019 18:43

Or read the Curious Incident... or was it doing so that prompted the question?

Thanks (0)
15th Jan 2019 08:21

Gosh, I was having a bit of a moment after a long day and had read about the whole 'why is the night sky not white?' thing a while ago and thought for some reason I'd ask AW rather than Googling, I think I wanted to share the curiosity or whatever.

When I remembered I had done this just now I expected to come back to a mod having told me off for being weird... not 26 serious answers...

If I was capable of blushing I would, thanks all :)

Thanks (1)
avatar
to Constantly Confused
15th Jan 2019 10:39

You provided some light relief (geddit?) from those two certainties we talk about in here ad nauseum – Brexit and taxes.

Thanks (0)
By DJKL
to Tax Dragon
15th Jan 2019 10:47

Yes, they are a constant plank of conversations on A Web

Thanks (0)
Share this content