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It is he that sitteth upon the circle of the earth, and the inhabitants thereof are as grasshoppers; that stretcheth out the heavens as a curtain, and spreadeth them out as a tent to dwell in:

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1 hour ago, Orraloon said:

Is the universe a circle?

 

No - look at the graph again

Observable being the key word

Edited by Ally Bongo

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3 hours ago, Kimba said:

Sorry for the late reply exile, been busy all day with stuff to do with my move home.  I would love to give you all the answers but I can't - I'm not the authority, I don't know everything. I make mistakes.  What I do know is that I have sinned and fallen short of the glory of God.  I know for a fact that the Bible gives me all the truth I need, so I don't rely on myself.   There is a lot of information out there if someone is willing to do their own research, that is what I, as a former atheist diid.  You CAN get to the truth, don't let anyone tell you otherwise.  Take care. 

I am just pointing out that you can work out what happens at an eclipse using a handy light source and ordinary objects. Actually it could be done easily with a torch (on a phone) and a CD and a ball, and try making shadows at different angles.

A flat disc's shadow varies from round to increasingly elongated, eventually a thin 'flat' shadow. 

A ball always casts round shadow. 

The shadow of the Earth on the Moon is always round. 

You don't need any authority other than your own eyes.

 

Edited by exile

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23 hours ago, Ally Bongo said:

No - look at the graph again

Observable being the key word

Sorry. Is the observable universe a circle?

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Well it's good to see that no one is disputing that a round object casts a round shadow (so the Earth must be round!)

We move on to pondering the shape of the whole universe (is that round too?) 

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So long as we don't know everything, some folk will just say it's magic or something in a teapot did it.

That's good that we don't know it all though.   The big mysteries to me look like fudges though (an open door for teapots)...   dark matter, dark energy and inflation (i.e. Ally's bit about the space the universe occupies having expanded faster than light, if I've got that right).

Some folk don't even believe in Newtonian mechanics though.   ...well ok they do, except strangely for the stuff they can't see :unsure: .   They seem to think scientists just have faith in their assertions.

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10 hours ago, Orraloon said:

Sorry. Is the observable universe a circle?

Obviously - the technical term would be circumference

Think of it as a ship's radar limit

22579188-modern-ship-radar-screen-with-g

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We put this to Carolyn Crawford, from the Institute of Astronomy at Cambridge University... Carolyn - The most straightforward part of that question is, how fast the universe is expanding now because this is something we actually measure. We call the current rate of expansion something called the Hubble constant, and that is really just a measure of how fast bits of the universe are moving away from us as a function of their distance. As you go further out away from the Earth, bits of the universe are travelling ever faster. For example if you go to 30 million light years away, maybe you've got a bit of universe receding away from us about 700 kilometres per second, go 10 times further to 300 million light years away, it's receding at 7,000 kilometres per second, and if you carried on going further and further away, yes, you do get a point where you're far enough away and that bit of the universe is moving away from us at speeds greater than the speed of light. So it is not a fundamental speed limit.

The key thing here to realise is that the expansion of the universe is caused by stretching of space and that can be at any speed it likes, much greater than the light speed. The thing that is constrained by the light speed is the rate that things can move through space. So the expansion of the universe is the stretching of space, and it's carrying the galaxies along for the ride, but any light, any signal or information from those galaxies can't travel faster than the speed of light.

In fact, the expansion of space is not constrained by how fast it's moving. It's constrained by how much stuff is in it, and that's going to determine whether the universe will contract or carry on expanding forever.

Diana - If space objects are moving away from us at a speed faster than light then the lights from them cannot travel fast enough to reach us.

Carolyn - All the evidence currently is that this expansion is getting ever faster and the universe is going to carry on expanding forever. The speed at which it expands isn't affecting the eventual fate of the universe, but what it does affect is what we can see of that universe, and how much of it we can see because if a galaxy is moving away from us faster than the speed of light, that means any photons of light leaving it can't travel across the space fast enough. It can't outrun the expansion of space. And so we have something called the observable horizon. Anything that's expanding further than the speed of light away from us, we will never see the light from those objects. And as the universe gets bigger and bigger, that horizon is going to shrink and we're going to see less and less of the universe, and that's really what's going to be affected by this expansion speed.

Diana - But what about that crunch theory?

Carolyn - Whether or not the universe actually collapses back down on itself depends on how much matter there is in the universe and how much stuff there is to pull it back together under gravity, and really, the current cosmological thinking is that with the presence of dark matter and dark energy, the universe is not going to contract. It's going to carry on and expand. It's going to expand faster and faster, and never go back to that big crunch at the end.

Diana - Current thought is, the universe will just keep expanding. To sum up, objects are moving away from us in space as space stretches, meaning that they can travel away from us faster than the speed of light. But those objects cannot move through space faster than the speed of light.

 

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Thanks Ally.   I was in the middle of typing some questions there.   Still got some, though may need to re-read your paste/post again slowly.

I thought the theory was that 'inflation' must have happened early in the history of the universe (by which, yes I 'understood' space expanding faster than light).   So is space still expanding faster than light?   The book I read may have been pre-dark energy and pre-Carolyn.   I can't keep up.

I'm missing something...   red shift is how we tell what is moving away faster.   The further away stuff is, the faster it's moving away, right?   Since stuff far away is also furthest back in time ('cause its light takes longer to reach us) does that mean stuff (or space) used to move (inflate) faster?   So then the universe is not expanding as fast now.

If it is expanding faster now, should we not see stuff closer to us (i.e. more recent in time) red-shifted further.   Feck, my tea must have been out when that bit of Horizon came on and I missed a crucial point :wacko:

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Don't things also depend on if we assume things like the speed of light were always the same back then?

If things in the very early universe were behaving differently, things could have been different back then, from what they look as if they were, seen from here and now...?

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15 hours ago, exile said:

Well it's good to see that no one is disputing that a round object casts a round shadow (so the Earth must be round!)

We move on to pondering the shape of the whole universe (is that round too?) 

What do you mean by "round"? I think it's important to have good definitions if you want to try to understand stuff.

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14 hours ago, Ally Bongo said:

Obviously - the technical term would be circumference

Think of it as a ship's radar limit

 

If we assume that the universe is flat, then the edge of that observable universe will be a circle.

This gets back to the importance of definitions. IMO, an object like the moon should be included in the observable universe. This isn't at the edge of our observable universe. My point being, that a "circle" only includes the points at the circumference. If you want to include all the points within that circle then mathematicians would refer to that as a "disc". 

This might seem a wee bit pedantic but, I think, if we are trying to understand complicated stuff like this it is important to be using the same definitions.

 

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25 minutes ago, Orraloon said:

If we assume that the universe is flat, then the edge of that observable universe will be a circle.

This gets back to the importance of definitions. IMO, an object like the moon should be included in the observable universe. This isn't at the edge of our observable universe. My point being, that a "circle" only includes the points at the circumference. If you want to include all the points within that circle then mathematicians would refer to that as a "disc". 

This might seem a wee bit pedantic but, I think, if we are trying to understand complicated stuff like this it is important to be using the same definitions.

 

15056399_10154677098606445_5839866955411

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18 hours ago, exile said:

Don't things also depend on if we assume things like the speed of light were always the same back then?

If things in the very early universe were behaving differently, things could have been different back then, from what they look as if they were, seen from here and now...?

 

Yes exactly! All cosmology seems to make assumption that everything we know now has always been the case. Yet the resulting theories are full of paradoxes. Something somewhere has gone wrong in cosmology....

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7 hours ago, Orraloon said:

What do you mean by "round"? I think it's important to have good definitions if you want to try to understand stuff.

You are of course right, and there are whole websites out there that explain round, curved, circular, elliptical...

but sometimes we need to keep things simple if we are dealing with this kind of approximation:

7e5d24b6cc20b8918bbd7d7210b51b8f.jpg

 

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But since you asked... this site for example explains the conditions under which the Earth would cast a circular shadow. If the Earth is a flat disk-like object there could only be a lunar exlipse at midnight, to create a circulat (as opposed to elliptical) shadow.

https://www.forbes.com/sites/startswithabang/2017/11/24/five-impossible-facts-that-would-have-to-be-true-if-the-earth-were-flat/#77419e647c4f

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6 hours ago, Orraloon said:

I'm just trying to help you get your terminology right. What shape would you call that?

 

Carnival mirror shaped

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7 hours ago, Orraloon said:

I'm just trying to help you get your terminology right. What shape would you call that?

 

It looks like a wonky onion thats been lying at the bottom of my fridge for too long. 

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17 minutes ago, TDYER63 said:

It looks like a wonky onion thats been lying at the bottom of my fridge for too long. 

I very much doubt anyone would want to sniff your onion though ..............

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12 minutes ago, Ally Bongo said:

I very much doubt anyone would want to sniff your onion though ..............

😂 the very thought brings tears to my eyes. 

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Ally, and all.  Lawrence and De Grasse are initiates.  They are doing the Externalisation of the Hierarchy - see Blavatsky and Bailey.  Please do not trust in man.  Let God be true and every man a liar.

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1 hour ago, Kimba said:

Ally, and all.  Lawrence and De Grasse are initiates.  They are doing the Externalisation of the Hierarchy - see Blavatsky and Bailey.  Please do not trust in man.  Let God be true and every man a liar.

Who do you think told you about God ?

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