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Posted

It seems like you think there is a dichotomy there. I'm not sure why. The Copernican principle is a reasonable assumption to make until and unless observations demonstrate otherwise, and the (weak) a anthropic principle is a reasonable couner to the idea that discovering physical laws are compatible with life is surprising and indicative of anything other than that we live in a universe that can support life.

Posted (edited)

I posted this thread after reading Michio Kaku`s The Future of the Mind. It explained the contradictions. But that paragraph is too long. I am lazy too write it. Maybe I shall stop posting threads after reading his book. Sorry.

Edited by Nicholas Kang
Posted (edited)

Are you asking whether the universe is should be :P homogenous or heterogenous?

"Wikipedia - Copernican Principle" gives two definitions, the latter being rather ambiguous. I thought the related cosmological principle was clearer.

Edited by MonDie
Posted

Dear MonDie,

 

Your proposal is making my mind even complicated because I have no idea of what does homogenous and heterogenous mean and the cosmological principle was a new stuff to me.

 

And one thing. I think both principles deal with the mind and philosophy, as in The Future of The Mind but nothing to do with the universe. Maybe Kaku have thought too much about both principles or he don`t even understand what they mean.

Posted (edited)

I meant "homogeneous". The "e" makes a difference.

 

Something is homogeneous if it's the same throughout (synonym: isotropic). For example, if a lake's water is homogeneous, a sample of that water should look the same regardless of where I took my sample at. If our universe is homogeneous, it should look the same regardless of what planet you occupy.

A thing is heterogeneous if it isn't the same through (synonym: anisotropic).

Edited by MonDie
Posted

No, I mean that, as far as we can tell the universe looks much the same regardless of where you are in it. If you were on a planet 5 billion light years away everything you see would be, in a general way, just what we see from the Earth.

Posted

But the stars and clusters organisation would be different from Milky Way, how is it possible for you to state that I can see the same thing from a planet 5 billion light years away if compared to Earth. Maybe the stars encircle the celestial sphere of Earth will encircle a different path in a planet 5 billion light years away. IIRC, andromeda M13 is 1.4 million light years away, a planet 5 billion light years away is many times much further, thus increasing the possibility of seeing something different. Am I right, Mr. Ophiolite?

Posted

But the stars and clusters organisation would be different from Milky Way, how is it possible for you to state that I can see the same thing from a planet 5 billion light years away if compared to Earth. Maybe the stars encircle the celestial sphere of Earth will encircle a different path in a planet 5 billion light years away. IIRC, andromeda M13 is 1.4 million light years away, a planet 5 billion light years away is many times much further, thus increasing the possibility of seeing something different. Am I right, Mr. Ophiolite?

 

The cosmological principle applies "on a large enough scale". Each grain of sand is unique, the dunes are different, there will be individual outcroppings - but if you look at a desert in large chunks the differences between grains, between dunes, between outcrops all average out and each "section" you look at will have a broadly similar appearance.

 

London is different from Penang in almost every way - but at a wide enough view they are identical; populated by carbon based lifeforms, net importers of goods and usable energy, having transport infrastructure within the city and superstructure linking other cities (which will form a similar distribution in both examples) etc. Do you see what I am getting at?

Posted (edited)

Dear Moderator imatfaal,

I have irritated you before. That is the only history I will never forget. Thanks again for using anology to explain Science. I grasp what you mean well. But before you could observe these planets, you can`t simply underestimate the problem. We are proud to say that our Physics is universal, which can be used to explain almost everything in the universe, except eternal questions and points where physics collapse, like in the singularity of a black hole. But we never send space probes to far galaxies. We never know what might contained in them, maybe more stuffs than Milky Way or less than that it-a dead galaxy, who knows? Tha answer will then be found when you have done observation, not just relying on hush-hush simulations done on supercomputers on a planet called Earth.

 

This is the answer to Mr. StringJunky. I have seen that picture before. But I shall warn scientist, maybe not suitable in my current age-15 years old- that nature always behave in the opposite way like you think. Nature always behaved unexpected, that`s why miracles exist, but this sounds like metaphysics and quasiscience, except from calculating the probability of a subatomic particle. ;)


Do you realise the unequally sized-black space/dots? They seem to vary in size, only the purple chains look the same.


The black spots are compact on the upper image but less on the lower image.

Edited by Nicholas Kang
Posted (edited)

This is the answer to Mr. StringJunky. I have seen that picture before. But I shall warn scientist, maybe not suitable in my current age-15 years old- that nature always behave in the opposite way like you think. Nature always behaved unexpected, that`s why miracles exist, but this sounds like metaphysics and quasiscience, except from calculating the probability of a subatomic particle. ;)

Do you realise the unequally sized-black space/dots? They seem to vary in size, only the purple chains look the same.

The black spots are compact on the upper image but less on the lower image.

The point of the picture was to illustrate visually for you what 'homogenous' means. It's structure - at a sufficient sample size - is basically uniform.

 

Nature is indeed unexpected - scientists continually find anomalies that put spanners in their theories - but in the end they get do closer to modelling reality and this is what is happening ...they are happy with that.

Edited by StringJunky
Posted

But the stars and clusters organisation would be different from Milky Way, how is it possible for you to state that I can see the same thing from a planet 5 billion light years away if compared to Earth. Maybe the stars encircle the celestial sphere of Earth will encircle a different path in a planet 5 billion light years away. IIRC, andromeda M13 is 1.4 million light years away, a planet 5 billion light years away is many times much further, thus increasing the possibility of seeing something different. Am I right, Mr. Ophiolite?

No, you are wrong. I think imatfaal has explained it to you, but just in case there is still some doubt, consider this analogy.

 

Take the train up to KL, go into the shopping mall at the base of the Petronas Twin Towers. Go up to the fourth floor - the one with the Kinokuniya book store. Look down at the people walking around on the floor below. Although the people there every day are different from the day before, their movements are very similar. You could not normally tell what day it was, or what time of day, just by watching their movements, or their clothing, or their average ages, etc.

Posted (edited)

The point of the picture was to illustrate visually for you what 'homogenous' means. It's structure - at a sufficient sample size - is basically uniform.

 

Nature is indeed unexpected - scientists continually find anomalies that put spanners in their theories - but in the end they get do closer to modelling reality and this is what is happening ...they are happy with that.

 

Do closer but not exact, what a poor thing. Then, when can we arrive at a state in which we get the exact nature value, but not closer to it? they are happy? But I am not happy, because this mean we haven`t fully discover the universe, we should keep ourselves inquisitive and move forward.

 

No, you are wrong. I think imatfaal has explained it to you, but just in case there is still some doubt, consider this analogy.

 

Take the train up to KL, go into the shopping mall at the base of the Petronas Twin Towers. Go up to the fourth floor - the one with the Kinokuniya book store. Look down at the people walking around on the floor below. Although the people there every day are different from the day before, their movements are very similar. You could not normally tell what day it was, or what time of day, just by watching their movements, or their clothing, or their average ages, etc.

 

In case you are angry with me, I shall (not aplogise) tell you not to be angry with my argument that seemed like irritating. Yes, according to your anology, we can know that they are people with similar movements, but their cells, tissues and philosophy and their reason of motions aren`t the same, they move in a similar way, but maybe different directions, with different objectives, to go to different shops, and with different cells in their bodies, with different respiration rate, different breathing rate... to infinity, The same as galaxies far away. You can observe galaxies moving far away, but you didn`t inspect the content of the galaxies, their number of stars are different, their planets` properties are different... to infinity. The aspects cancel out each other but what about aspects that couldn`t be cancelled out and persisted for long? And don`t forget they are only simulations but not observations. Observations are always more reliable than simulations that are limited to aspects that are unpredictable.

You must have came to KL before since you know Kinokuniya book store.I went there before. It is big and wide. Have you come to Penang before?

Edited by Nicholas Kang
Posted

Nicholas - no one is getting irritated or angry :) Maybe we just express ourselves a little too strongly - but there is no anger.

 

 

Yes, according to your anology, we can know that they are people with similar movements, but their cells, tissues and philosophy and their reason of motions aren`t the same, they move in a similar way, but maybe different directions, with different objectives, to go to different shops, and with different cells in their bodies, with different respiration rate, different breathing rate... to infinity,

 

Yes - you are correct; but it doesn't matter! You need to calculate the number of people who can safely get on a ferry - do you need to know the colour of their hair, what scent they are wearing, their political views? Do you need to know the funnel design or whether it is a dieselmotor or steam turbine. No - you need their mass, their number, and the description and safety parameters of the ferry.

 

If I am wanting to do an cosmology on a large scale I must assume (note; assume not know) that things on a larger scale are broadly homogeneous. I need to be able to say that the reason superclusters x, y, and z behave in the way they do is part of a universal rule and not because they happen to be where they are.

 

These are assumptions, axiomata, assertions... - we use the cosmological principle that large scale space is homogeneous and isotropic because we have no reason not to, it is very useful, and cosmology is impossible without it.

Posted

Yes, I need to know the power rating, voltage etc. of the diesel motor and the steam engine to calculate the maximum load and capacity of the passanger of the ferry. I need to know their political view in case someone supporting Iran and North Korea onboard the ferry and say I hate US and even kill Americans, just maybe, I won`t kill any americans, that is just an example. I need to know their hair colour to calculate how much people have boarded the ferry, according to hair colours, to be presented in the statistics reports, so next time, I may paint the ferry with the most popular colour to attract more passangers. I need to know... for ... reasons. Of course, I need their mass, numbers...

 

You assume, you have done simulations, but you never send probes out there. You never point your telescope and peer into the heart of every galaxy(it is impossible but we cannot ignore that fact, every aspects counts)

 

Nicholas - no one is getting irritated or angry :) Maybe we just express ourselves a little too strongly - but there is no anger.

 

I mean the post about dwarf planets which you told me about those crazy IAU scientists. I have written sorry for at least 10 times.

 

 

If I am wanting to do an cosmology on a large scale I must assume (note; assume not know) that things on a larger scale are broadly homogeneous. I need to be able to say that the reason superclusters x, y, and z behave in the way they do is part of a universal rule and not because they happen to be where they are.

 

You mean I don`t understand science? Yes, it seemed that I don`t because science explains but not simply stating that they behaves like that because they happen to be where they are. Now, imatfaal, I shall say that I don`t mean they happen to be where they are, I just say that we haven`t explore them, fully reveal nature`s secret, thus we shouldn`t immediately assume that the universe is homogenous. Yes, from some perspectives, yes, but from the picture posted by stringjunky, I can`t see any homogenous aspects there. Maybe homogenous because when you place a human who learn the word Universe on a planet 5 billion ly away, he will still consider the space as the Universe.

 

I repeat my statement clearly. We aspect the universe to be homogenous because it looks the almost the same anywhere from every perspectives, am I right? Now, if yes, then the only way to deny this fact is simply imagine taking a spacecraft to the space just above the milky way. Now, turn back your spacecraft, look at the milky way, it looked like a barred-spiral galaxy, yes it is. Now, you assume you know the number of stars in the Milky Way. Turn your spacecraft facing towards M13 Andromeda, you see it as a spiral galaxy too. fly your craft halfway between M13 and Milky Way. Stop. Turn your craft to a position where both galaxies are located on your sides. When viewing from one point, M13 is on your left, Milky Way is on your right. Turn your position 180 degrees, now M13 is on your right and Milky Way is on your left. Is the position homogenous? Plus the motion of both galaxies, expansion of space... Now, imagine a supercluster, substitute M13 with supercluster A and Milky Way with supercluster B, you get the same answer.

 

These are assumptions, axiomata, assertions... - we use the cosmological principle that large scale space is homogeneous and isotropic because we have no reason not to, it is very useful, and cosmology is impossible without it.

 

It is useful, but until one limit, then it fails, can you use this principle to explain galaxies beyond the cosmic horizon 13.7 billion ly/46 billion ly due to space expansion? New theory will emerge, than cosmology is possible without it.

Posted

Nicholas,

you need to get a sense of scale. Consider two dining room tables. On the scale of the solar system they are identical. On the scale of furniture they are similar. On the scale of atoms they are radically different. That's all we are saying.

 

(And to answer your earlier question, I know KL quite well. I saw Mohamed Ali fight Joe Bugner there in the 1970s and was last there 18 months ago, and many times in between. Our office is just opposite the twin Towers. I've only made it to Penang once.)

Posted

...

I repeat my statement clearly. We aspect the universe to be homogenous because it looks the almost the same anywhere from every perspectives, am I right? Now, if yes, then the only way to deny this fact is simply imagine taking a spacecraft to the space just above the milky way. Now, turn back your spacecraft, look at the milky way, it looked like a barred-spiral galaxy, yes it is. Now, you assume you know the number of stars in the Milky Way. Turn your spacecraft facing towards M13 Andromeda, you see it as a spiral galaxy too. fly your craft halfway between M13 and Milky Way. Stop. Turn your craft to a position where both galaxies are located on your sides. When viewing from one point, M13 is on your left, Milky Way is on your right. Turn your position 180 degrees, now M13 is on your right and Milky Way is on your left. Is the position homogenous? Plus the motion of both galaxies, expansion of space... Now, imagine a supercluster, substitute M13 with supercluster A and Milky Way with supercluster B, you get the same answer.

The scale of your example far too small to show the homogenous nature of the large-scale universe or lack of it in the way it is being explained to you ...you need an expanse of a few hundred million light years to start to see the uniform filamentous - cobwebby - nature of the universe. When I look at that picture I linked to it tells me that the physics is very likely the same everywhere. Here's the universe across 1 billion light years and we are in the centre in Virgo:

 

http://www.atlasoftheuniverse.com/superc.html

 

At 14 billion:

 

http://www.atlasoftheuniverse.com/universe.html

Posted

A sense of scale. Good and great. I like it. You mean the scale of the universe? The smaller the radical the difference? Now, 2 dining room tables. Well, Ophiolite dining table isn`t a good example. The problem is that the universe isn`t as simple as the dining table.

 

Our office? Do you mean SFN has a branch in Malaysia? You are a geologist, aren`t you? Your company run geology busniess? Never heard of geology busniess.


The scale of your example far too small to show the homogenous nature of the large-scale universe or lack of it in the way it is being explained to you ...you need an expanse of a few hundred million light years to start to see the uniform filamentous - cobwebby - nature of the universe. When I look at that picture I linked to it tells me that the physics is very likely the same everywhere. Here's the universe across 1 billion light years and we are in the centre in Virgo:

 

http://www.atlasoftheuniverse.com/superc.html

 

At 14 billion:

 

http://www.atlasoftheuniverse.com/universe.html

 

Computer simulation? Telescope(s) survey?

Posted

A sense of scale. Good and great. I like it. You mean the scale of the universe? The smaller the radical the difference? Now, 2 dining room tables. Well, Ophiolite dining table isn`t a good example. The problem is that the universe isn`t as simple as the dining table.

 

Our office? Do you mean SFN has a branch in Malaysia? You are a geologist, aren`t you? Your company run geology busniess? Never heard of geology busniess.

 

Computer simulation? Telescope(s) survey?

They are simulations based on available data.

Posted

A sense of scale. Good and great. I like it. You mean the scale of the universe? The smaller the radical the difference? Now, 2 dining room tables. Well, Ophiolite dining table isn`t a good example. The problem is that the universe isn`t as simple as the dining table.

The point is that, at certain scales, it is that simple. It seems that where ever we might be in the universe we would see galaxies that have a limited range of sizes and structures, composed of stars and gas and - apparently - dark matter, and assembled in groups, some small some large. It's the same everywhere.

 

Our office? Do you mean SFN has a branch in Malaysia? You are a geologist, aren`t you? Your company run geology busniess? Never heard of geology busniess.

I mean the company I work for. It is a large multi-national service and supply company within the oil and gas drilling industry. I do not work as a geologist: that was simply my original training and my continuing interest.

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