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jn1 said..

Cambodge said..

Crusoe - Except for light which seems to have a constant speed regardless of the observer and irrelevant of any stationary point or moving point. Light is the weirdest thing in the four-dimensional awareness we have of our Universe.

Not true. The Electromagnetic radiation's speed (including light) is not constant. It varies depending on the matter is it travelling through.. hence the term velocity factor.

Was simplifying...ok, through a vacuum....speed of light is independent of any relative motion of the observer.

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Cambodge said..

jn1 said..

Cambodge said..

Crusoe - Except for light which seems to have a constant speed regardless of the observer and irrelevant of any stationary point or moving point. Light is the weirdest thing in the four-dimensional awareness we have of our Universe.

Not true. The Electromagnetic radiation's speed (including light) is not constant. It varies depending on the matter is it travelling through.. hence the term velocity factor.

Was simplifying...ok, through a vacuum....speed of light is independent of any relative motion of the observer.

but the universe isn't a vacuum. When you look back in time (ie: look at far away objects billions of years ago), it was less of one. Yet, Physicists make the assumption that EMR speed is constant ?. There would have been a time in the Universe's life when the speed of light was walking pace. Yet, those early days are stretched out all around us.

This thread reminds me of a conversation I had with my son when he was six years old...

My son: "Dad, what happened before the big bang?"

Me: "I don't know. A lot of smart people have tried to work that out but they can't be sure of the theories they have come up with..." (yes, I was winging it and out of my depth...)

My son: "Well, maybe... there was this big cloud of gas that shrunk down to a point then it went bang?or maybe..." (he went on for some time with a few different ideas that sounded equally plausible)(he then sighed heavily and said)

"Hmmfff.... this is too hard... even for a six year old!"

I was (and remain) impressed that not only could he think intelligently about the question at age six, he had the calm belief that of course a six year old should be able to understand the origins of the universe!

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Tux said..
What if its not really big its actually really small ?

Why does the alphabet have to go from A to Z...why can't in start from somewhere else

Yep that's what I was thinking; if we were able to keep burrowing down maybe there are galaxies inside atoms?

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Skid said..
I was (and remain) impressed that not only could he think intelligently about the question at age six, he had the calm belief that of course a six year old should be able to understand the origins of the universe!

Barn would say you have good genes. Your son could be the the next Nobel Prize winner.

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Mark _australia said..

Anyone got that awesome presentation re: the smallest thing we can see out to the largest? Its equally amazing

The human body is about the half way size between the smallest thing in the universe and the universe itself. [boooom]

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Mark _australia said..
And to accelerate something to more than the speed of light takes an infinite amount of energy so is impossible. Yet some stuff is moving away from us faster than that speed according to the video.

The universe is expanding. We don't know why. No idea.

If you look ...up, you see the universe. Objects near to use, like the moon, are not moving away from us. Ditto objects in, say, our own galaxy.

However, the further out you look, using bigger and better telescopes, the more things are moving "away" from us. (quotes for emphasis). And it doesn't matter which way you look, north, south, east, west, the further away an object is the faster it is moving away from us.

So, what the **** does this mean?

You can figure it out yourself. And I argue that only then do you really understand it anyway. Rediscovery = true learning and understanding.

Everything is moving away from us, and the further away the faster it is moving away (i ignore local things like our own galaxy for clarity, and as per the topic of this thread the universe is big, really big). The best analogy is a balloon.

A balloon?

Take a balloon and blow it up, to about 20%. Now draw a few dots on it that represent objects. Some close, some far apart.

Blow the balloon up some more and watch what happens.

The dots that were originally close are further apart, but the dots that were originally far apart are now really far apart; they have moved away from each other at a much faster rate than the ones that were originally close together.

This is because the balloon is expanding. The important thing to notice is that the objects aren't moving away from each other, the very fabric of the balloon is expanding!

Also, the universe doesn't expand at a constant rate. We can see that at some point in the past it was actually expanding at a rate faster than light itself. Nothing can travel faster than light, the dots on the ballon can't move faster than light, but the very fabric of spacetime itself doesn't hold to this rule; it's not an object in spacetime, it is spacetime.

Looking into the very distant future eventually the universe will expand so much, galaxies will be so distant to us and moving away at such a rate of speed that we won't be able to see them, at all. Whatever is alive in the distant future will not be able to see anything but our local galaxy.

The end.

tl;dr beer before wine and you'll be fine.

P.S. grew up on Carl Sagan. I have to agree with comments saying that some videos, presenters and the like are very much "we are smarter than you". That De Grasse guy is a bit of a dick. Likewise Dawkins. Somehow they turn exploration and mystery into an argument.

Fun fact of the day: Given enough time and gravity hydrogen can name itself.

Are we ourselves expanding ?

Yes. No.

Because everything is expanding equally along with you there is nothing to compare yourself to. Your tape measure is also expanding. 1cm is still 1cm. Your gut is still too big.

Perhaps a good, and somewhat different, analogy is monetary inflation. Say the entire economy is inflating at 5%, your salary, the average price of consumer goods, and so on. If you get a 5% raise is your salary actually getting any bigger?

Like the dots drawn on an expanding ballon we grow, and the further the distance between two dots the great that distance grows. That balloon analogy is really the best one.

Some would say that there's incontrovertible evidence that the earth is expanding. Others might disagree.

en.wikipedia.org/wiki/Expanding_Earth


This would be a good topic of research for Heavy weather. ( Once we've proved that it's not flat, of course. )

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evlPanda said..

Mark _australia said..
And to accelerate something to more than the speed of light takes an infinite amount of energy so is impossible. Yet some stuff is moving away from us faster than that speed according to the video.

The universe is expanding. We don't know why. No idea.

If you look ...up, you see the universe. Objects near to use, like the moon, are not moving away from us. Ditto objects in, say, our own galaxy.

However, the further out you look, using bigger and better telescopes, the more things are moving "away" from us. (quotes for emphasis). And it doesn't matter which way you look, north, south, east, west, the further away an object is the faster it is moving away from us.

So, what the **** does this mean?

You can figure it out yourself. And I argue that only then do you really understand it anyway. Rediscovery = true learning and understanding.

Everything is moving away from us, and the further away the faster it is moving away (i ignore local things like our own galaxy for clarity, and as per the topic of this thread the universe is big, really big). The best analogy is a balloon.

A balloon?

Take a balloon and blow it up, to about 20%. Now draw a few dots on it that represent objects. Some close, some far apart.

Blow the balloon up some more and watch what happens.

The dots that were originally close are further apart, but the dots that were originally far apart are now really far apart; they have moved away from each other at a much faster rate than the ones that were originally close together.

This is because the balloon is expanding. The important thing to notice is that the objects aren't moving away from each other, the very fabric of the balloon is expanding!

Also, the universe doesn't expand at a constant rate. We can see that at some point in the past it was actually expanding at a rate faster than light itself. Nothing can travel faster than light, the dots on the ballon can't move faster than light, but the very fabric of spacetime itself doesn't hold to this rule; it's not an object in spacetime, it is spacetime.

Looking into the very distant future eventually the universe will expand so much, galaxies will be so distant to us and moving away at such a rate of speed that we won't be able to see them, at all. Whatever is alive in the distant future will not be able to see anything but our local galaxy.

The end.

tl;dr beer before wine and you'll be fine.

P.S. grew up on Carl Sagan. I have to agree with comments saying that some videos, presenters and the like are very much "we are smarter than you". That De Grasse guy is a bit of a dick. Likewise Dawkins. Somehow they turn exploration and mystery into an argument.

Fun fact of the day: Given enough time and gravity hydrogen can name itself.

Good post - interesting. Thank you.

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evlPanda said..
Yes. No.

Because everything is expanding equally along with you there is nothing to compare yourself to. Your tape measure is also expanding. 1cm is still 1cm. Your gut is still too big.

Perhaps a good, and somewhat different, analogy is monetary inflation. Say the entire economy is inflating at 5%, your salary, the average price of consumer goods, and so on. If you get a 5% raise is your salary actually getting any bigger?

Like the dots drawn on an expanding ballon we grow, and the further the distance between two dots the great that distance grows. That balloon analogy is really the best one.

If so , am i and my gut expanding at the speed of light ?
If everything is expanding at the speed of light and everything is relative then how do we know we are expanding. I must be expanding slower to see other things moving apart.???
I once read a book stating that there is no reason for time to move forward , it could have just as easily been going backwards according to maths. And we could mathematically be existing in a two dimensional world perceiving it as three dimensional.
Could we be shrinking and space isn't shrinking as fast to give us a perception of expanding ?
Wow ! im not even drunk around a camp fire.

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Imax1 said..

Could we be shrinking and space isn't shrinking as fast to give us a perception of expanding ?
Wow ! im not even drunk around a camp fire.

Good point. They reckon it was the discovery of the campfire that triggered the explosion of thinking that makes us human.
www.smithsonianmag.com/science-nature/fire-good-make-human-inspiration-happen-132494650/

Modern humans are running on momentum now that we no longer have campfires. How many generations of humans raised on central heating do you think it will take before we lose the ability to think?

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Ian K said..

Modern humans are running on momentum now that we no longer have campfires. How many generations of humans raised on central heating do you think it will take before we lose the ability to think?

That is a deeeep question, but a valid one. Like the citizen of ancient times. Facing nasty amigos on all sides, they needed to be self sufficient, resourceful and tough. When life got better and easier for them, them went all jelly and soft. Hence the collapse of a great nation.

Fast track to now, technologies are presented to us on a plate. Driverless cars, instant messages, etc. No need to worry about how things work anymore. Is it any wonder why Straya is finding it hard to attract young folks to do science and maths ?

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Jupiter said..

Red-shift uses electromagnet radiation. As your doubts about the accuracy of the measurements due to the distortions caused by gravitational waves as well as influences from other heavenly object, it is being taken care of by "filtering". Super Computers are able to filter out the effects you mentioned.

My issue is this:

The above works well for known distances and through a known medium

The gravitational lensing and diffraction caused by objects is different for every single light beam vector in the universe - as the light beams pass a different number of objects and through different media.
Red shift is an approximation at best, even with the super computers' input. Think about it - we have no idea exactly what lies between us and the edge of the known universe (really, watch the video...its huge) so any modelling really does not know what happens to that light before it gets here.
Red shift is presented as proof of a concept nobody is sure is true anymore (big bang) but both are still espoused as total 100% truth in all the highschool texts.
I suggest that red shift is about the worst possible proof of an expanding universe as the light could be affected by so many things we don't know about. Its like using your analogous traffic cop's doppler radar on a car at 1000km away thru a dust storm. Yeah I'd take it to court, wouldn't you?

I'm sure a lot of cosmologists would have tried to make a name for themselves in the early days by coming up with an alternative explanation for the observed redshift. But now it's so tied up in our explanation of things, you'd have to unravel a whole new view of the universe to fit in with an alternative. The rotational speed of spiral galaxies is determined using red shift for instance. Hence the search for dark matter, because the rotational speeds observed doesn't match the expected masses of the galaxies.
en.wikipedia.org/wiki/Galaxy_rotation_curve

www.google.com.au/url?sa=t&source=web&rct=j&url=https://m.youtube.com/watch%3Fv%3DxzAh8vmDiSE&ved=0ahUKEwj7ufvi-o7UAhXHG5QKHZMcAGoQt9IBCJ0BMBw&usg=AFQjCNGysKXgUkVAeKVDER8Pv2LuaM-xUA


www.google.com.au/url?sa=t&source=web&rct=j&url=https://m.youtube.com/watch%3Fv%3DAanQ2mY2jjc&ved=0ahUKEwi4vLiG-47UAhVCJZQKHRsbDOwQo7QBCBswAA&usg=AFQjCNEVfq3aq4q4N-CVEOgu2eHrQtiang



Between the mumbo jumbo there are some interesting points... I actually enjoy the mumbo jumbo as much as the "facts " but enjoyable to watch....

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Mark _australia said..
Red shift is presented as proof of a concept nobody is sure is true anymore (big bang) but both are still espoused as total 100% truth in all the highschool texts.
I suggest that red shift is about the worst possible proof of an expanding universe as the light could be affected by so many things we don't know about. Its like using your analogous traffic cop's doppler radar on a car at 1000km away thru a dust storm. Yeah I'd take it to court, wouldn't you?

Perhaps not the best technique available for the time being. But is there an alternative technique to prove that the universe "is not" expanding?

Science is still a trial and error when it comes to astronomy. I am, just like you, hold many questions and doubts about all those weird and strange theories. The "String" theory is one which comes to mind. However, just because I am out of my depth doesn't mean that it may be wrong.

Scientists, especially the "theoretical" astronomers, are mostly making up theories based on their wildest imagination. Space cadets in some people's mind. But please note that Mr. Einstein was known for dreaming up the wildest theories without actually being able to physically testing them. The E = MC^2 is one which come to mind.

Personally, I think astronomy is all good fun, but mean bugger all to me in my lifetime, or even to the next 1,000 years. What is the point of going to Mars ? To see if we are tough enough and resourceful enough to live in a hostile place with bugger-all to see and do ? The earth is good enough for me, and I only needed a small patch for myself,

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Jupiter said..
Scientists, especially the "theoretical" astronomers, are mostly making up theories based on their wildest imagination. Space cadets in some people's mind. But please note that Mr. Einstein was known for dreaming up the wildest theories without actually being able to physically testing them. The E = MC^2 is one which come to mind.

I don't think that's how science works - scientists don't dream up theories.

There is a long backstory to e=mc2
www.scientificamerican.com/article/was-einstein-the-first-to-invent-e-mc2/?error=cookies_not_supported&code=27792321-f9f0-442e-b5f8-fb87b19db963


Part of the scientific method is using the understanding gained by major thinkers who have gone before in order to make intellectual progress.

Isaac Newton summed it up in a letter to Robert Hooke in 1676;

"What Descartes did was a good step. You have added much several ways, and especially in taking the colours of thin plates into philosophical consideration. If I have seen a little further it is by standing on the shoulders of giants."

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Mark _australia said..

Jupiter said..

Red-shift uses electromagnet radiation. As your doubts about the accuracy of the measurements due to the distortions caused by gravitational waves as well as influences from other heavenly object, it is being taken care of by "filtering". Super Computers are able to filter out the effects you mentioned.

My issue is this:

The above works well for known distances and through a known medium

The gravitational lensing and diffraction caused by objects is different for every single light beam vector in the universe - as the light beams pass a different number of objects and through different media.
Red shift is an approximation at best, even with the super computers' input. Think about it - we have no idea exactly what lies between us and the edge of the known universe (really, watch the video...its huge) so any modelling really does not know what happens to that light before it gets here.
Red shift is presented as proof of a concept nobody is sure is true anymore (big bang) but both are still espoused as total 100% truth in all the highschool texts.
I suggest that red shift is about the worst possible proof of an expanding universe as the light could be affected by so many things we don't know about. Its like using your analogous traffic cop's doppler radar on a car at 1000km away thru a dust storm. Yeah I'd take it to court, wouldn't you?

If the red shift was caused by various other factors then wouldn't we expect it to be inconsistent across the sky? Wouldn't we expect some bits to be red shifted but others to be blue shifted? But it appears that everything in every direction is red shifted. I think it's the consistency of the observations that suggests there's a macro cause independent of localised properties.

^^ I am not talking about if red shift happens (it does) or claiming there is no expansion (yes of course its expanding).

I am saying red shift could not be used to measure a speed of expansion reliably, due to the massive interference between the end of space, and us. It is conjecture, theory, modelling. NOT the same as using doppler to measure speed of an object on earth.
So when they say objects an impossibly far away distance are moving at Xkmh and everybody accepts it- geez.
Then to use that assumption to build other concepts upon, its philosophy not science.

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Crusoe said
- Light is the weirdest thing in the four-dimensional awareness we have of our Universe.

Disagree slightly, light is an indicator of the weirdest thing, which in my opinion is time!
We expect it to be a constant, but the speed of light tells us it's relative!
Firstly to how fast you're traveling, and secondly to the number of protons and neutrons in the near vicinity. ("Near" being relative of course)

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Mark _australia said..
^^ I am not talking about if red shift happens (it does) or claiming there is no expansion (yes of course its expanding).

I am saying red shift could not be used to measure a speed of expansion reliably, due to the massive interference between the end of space, and us. It is conjecture, theory, modelling. NOT the same as using doppler to measure speed of an object on earth.
So when they say objects an impossibly far away distance are moving at Xkmh and everybody accepts it- geez.
Then to use that assumption to build other concepts upon, its philosophy not science.

Space is pretty empty. Like it's mostly empty. 99.999 ...99% empty. The medium the light has travelled through is almost, if not entirely the vacuum of empty space. There's no interference; it's space.

What's your hypothesis? It's probably been raised before (99.999 ...99% chance).

Red Shift is pretty accepted stuff, and understandably so. It's not like string theory or anything. It's very much in the observable phenomenon type of science, not theoretical.

By the way you can't doubt red shift and accept expansion at the same time; red shift is the only physical evidence we have for it. So if you doubt the accuracy of the measurements then you have to equally doubt the explanation behind the observations, that the universe is expanding.

Keep on doubting until you're satisfied, at worst you'll learn heaps of interesting stuff. : )

- - - - - -

One thing I noticed years ago, but can't quite describe or explain very well, is that practically all of modern science has come from observing rainbows, and just been extended onwards. Red shift is an example.

^^ rainbows- perfect. Just like a diffraction grating bends light so do other objects. Yes space is 99.9% empty but think about the distance we are talking. Light will pass a lot of objects and be bent which = slowed. How many planets and lumps of crap has it passed?
Now, how many lumps has it passed on a certain bearing say noth at 45 deg from you now, vs south at 45deg? There will be a variance.

So YES red shift happens
YES it proves expansion

BUT to thereby ascribe any sort of ability to measure it so accurately that we can say object #1 is moving away faster than object #2 is ridiculous when they are so, so far away.. Commonsense tells us that. Happy to be proven wrong.

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azymuth said..

Jupiter said..
But please note that Mr. Einstein was known for ......... The E = MC^2 is one which come to mind.

There is a long backstory to e=mc2
www.scientificamerican.com/article/was-einstein-the-first-to-invent-e-mc2/?error=cookies_not_supported&code=d07fca5c-e1ab-4cbc-8d05-dac22f9cbff4

Hang on, wasn't there a documentary a few years ago about that Einstein fella discovering that E=MC2 was what put bubbles in beer??

made more sense than a lot of other scientific mumbo jumbo stuff.

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Mark _australia said..
^^ rainbows- perfect. Just like a diffraction grating bends light so do other objects. Yes space is 99.9% empty but think about the distance we are talking. Light will pass a lot of objects and be bent which = slowed. How many planets and lumps of crap has it passed?
Now, how many lumps has it passed on a certain bearing say noth at 45 deg from you now, vs south at 45deg? There will be a variance.

So YES red shift happens
YES it proves expansion

BUT to thereby ascribe any sort of ability to measure it so accurately that we can say object #1 is moving away faster than object #2 is ridiculous when they are so, so far away.. Commonsense tells us that. Happy to be proven wrong.

Being skeptical is good. In fact, I am probably one of the most skeptical person here and other forums. But being skeptical needs not be for skeptical sake, otherwise one becomes a mere cynic.

As you know, we are not talking about objects just around the block. We are measuring, perhaps estimating, the speed of the objects moving at incredible rate of "light years" ! So there is my point, how accurate one needs to be when it is so far. They are so far that it may take us "billions of billions" of years if we travel in our trusty Holden Kingswood. A bit sooner may be if we have a rocket of a giant proportion.

For me, I just accept that Red-shift can indeed measure "with a degree of accuracy" the speed of the objects. I am not going to argue about whether it in fact a couple of light years more or less.

By the way, The Red-shift technique is the accepted method of measurement. It proved that objects are moving away. Is there an alternative method that will prove otherwise ?

^ Red shift correlates with other methods of measurement like parallax and the measured brightness of standard candles.

^^ it does not work for a candle moving at near c

the candle blows out.

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Mark _australia said..
^^ it does not work for a candle moving at near c

the candle blows out.

not exactly, candle flame traveling at C speed in open vacuum space will not be affected by air resistance

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Macroscien said..

Mark _australia said..
^^ it does not work for a candle moving at near c

the candle blows out.

not exactly, candle flame traveling at C speed in open vacuum space will not be affected by air resistance

Would candle burn more brightly in a vacuum ?