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Posted

After reading a number of scientific articles about far distant galaxies and the

estimated age of the universe I began wondering how we could supposedly

see light from objects that are 12 billion light years or so away. This is

supposed to be light from nearly the beginning of time and space.

 

If we agree to believe that the big bang actually happened then this would

mean that at some point we were much closer (cosmologically speaking)

to those distant objects.

 

Since matter travels at a mere fraction of the speed of light is seems

somewhat dubious that any light emitted from that object at the beginning

of time, as we know it, would not already have passed us a long, long, long

time ago.

 

We have developed many tools for measuring distance from relatively

nearby objects. I suspect that these work well up to a point, at which

they start to break down somehow.

 

Could it be that using light to measure distance works well when

objects have been relatively close together since the beginning and

then breaks down when objects become very far apart ?

 

Maybe the big bang never happened and objects that are far away have

always been far away ?

 

Doesn't the fact that these supposed far distant objects are 12 billion light

years away mean that the universe is far older than 14 billion light years

or have these objects been moving at the speed of light ?

 

I found an article in Wikipedia which attempts to explain this but I'm not

sure I buy it. Look for 'Metrical_expansion_of_space'.

Posted (edited)

 

If we agree to believe that the big bang actually happened then this would

mean that at some point we were much closer (cosmologically speaking)

to those distant objects.

 

I agree that the big bang actually happened. The big bang, as cosmologists normally understand it, does not involve having matter move (except for individual random motions).

 

It is true that distant objects (distant material in general, anything emitting light) was much closer.

 

It didn't move. But it got farther away.

Google "wright balloon model" and watch it to see how.

 

 

Since matter travels at a mere fraction of the speed of light is seems

somewhat dubious that any light emitted from that object at the beginning

of time, as we know it, would not already have passed us a long, long, long

time ago.

 

Since matter is not traveling (traveling matter has somewhere it is going, that it is getting closer to) it is irrelevant that it can only travel at less than c.

 

In General Relativity, distances can increase at greater than c. And the longer distances typically do :D

 

Again you should watch that 3 minute balloon model movie and think about it. The little wiggly things are photons of light traveling at a fixed speed over the balloon surface. Often the galaxy that they are traveling towards is getting farther away.

http://www.astro.ucla.edu/~wright/Balloon2.html

 

But notice that as expansion slows, after a long time, the photon will begin to make progress and get closer to its destination. It's a great lesson for all of us. If you hang in there and keep trying you may get there. :D

 

Look for 'Metrical_expansion_of_space'.

 

That is a bum steer, Purin. You mean look for Metric_expansion_of_space

If you google what you said, you don't get anything. If you google what I said, you get the Wikipedia article on the metric expansion of space.

By and large it is a pretty good article.

Edited by Martin
Posted

If the light from a galaxy took 13.66 billion light years (almost the age of universe) to get here, it was emitted when it was 0.205525 billion light years away and is now 43.762 billion light years away. This is not because of the movement of galaxies but because of the expansion of space.

 

The universe was more dense long ago but the big bang is currently looked at as not coming from a singularity. At the edge of the observable universe we would probably see a similar view in every direction as we do from the Milky Way.

Posted

In reply to Martin....

 

I understand the balloon concept and have seen the applet on the net. I have

a little difficulty mentally translating a 2d surface to a 3d world we actually live in.

 

Since the light from the far distant object is not all that far away at an earlier time

the speeds of the far distant expansion should not be an issue as with a closer

proximity expansion. Light from nearby galaxies has no problem getting here. Why

would it be any different ?

 

It still seems that it should exceed the speed of the early expansion and reach us in fairly short order in the distant past.

 

Which begs the question of being able to see the

same light photons at two widely separated time intervals.

Posted
If the light from a galaxy took 13.66 billion light years (almost the age of universe) to get here, it was emitted when it was 0.205525 billion light years away and is now 43.762 billion light years away. This is not because of the movement of galaxies but because of the expansion of space.

 

The universe was more dense long ago but the big bang is currently looked at as not coming from a singularity. At the edge of the observable universe we would probably see a similar view in every direction as we do from the Milky Way.

------------------------------

The X-ray image of the distant cluster is comprised of just 280 photons—individual parcels of light—collected during a 12.5-hour exposure. By comparison, on a sunny day the human eye is flooded by about 10 quadrillion photons per second.

http://www.ur.umich.edu/0405/Mar07_05/02.shtml

-------------------------------

Admittedly, I am not convinced BBT is valid, no longer wish to argue the point but am really confused on this 'distance' relationship to what we think we are seeing. I understand that objects in an expanding U, will be in different places 2-5 or 10 billion years in the past and I understand some think emitted energy travel time has changed from today's -C-, but has this been proved.

 

If we observe photons, which are not very many from more distant objects, that object emitted those photons according to there distance was momentarily at a precise distance from the receiving object. Where it was before, that energy has long past us by and where it is today will reach us in time, but at the time that photon was released is measurable at a constant -C- (186,200m/p/s).

 

Using the same site and the diagram of higher red shifts per distances; How could the observation be the same from observations made from distant points. Regardless how you understand 'center' with regards to a self contained U in rapid expansion, said to be in all direction (not material) then the effects of expansion IMO cannot be equal in every quadrant of that object, sphere or other wise.

 

 

purintjp;

"Which begs the question of being able to see the

same light photons at two widely separated time intervals."

 

Under any scenario, light (energy) reaches you eyes or whatever lens from ONE object, in that fraction of time. Your not going to receive any energy (photon) from one object in more than one time. The ten quadrillion or so photons effecting the earth each second where sent out 8 minutes ago, which our planet actually runs into after 8 minutes of travel around the sun @ 1,000 m/p/h...Even reflected light, are new photons such as you see from a blue sky or off the moon. At least thats the way I understand it....

Posted

Admittedly, I am not convinced BBT is valid, no longer wish to argue the point ...

Neither am I. Hence, my screen name. In actuality we don't know $h!t. Knowledge is changing quickly and that should continue. I suspect we will never be able to say "NowThatWeKnow". :) So, I am just attempting to relay what I think is mainstream today. Knowing that much of it will change tomorrow.

 

... How could the observation be the same from observations made from distant points. Regardless how you understand 'center' with regards to a self contained U in rapid expansion, said to be in all direction (not material) then the effects of expansion IMO cannot be equal in every quadrant of that object, sphere or other wise.

As the balloon expands the distance between every dot (qalaxy) increases. Each specified distance will expand equally in all directions. The further the distance, the faster the speed. There is no center to the surface of the balloon.

Light is sent out as a continuous beam over billions of years and not just a flash to be monitored at a particular time. As the distance of two objects separating increases, the light will redshift until it can no longer be seen.

 

Just a few of my thought addressing what I think you were saying.

Posted (edited)
In reply to Martin....

 

I understand the balloon concept and have seen the applet on the net.

 

Excellent! Pleased to meet you!

I have

a little difficulty mentally translating a 2d surface to a 3d world we actually live in.

 

It is great you've tried. The analog would be a hypersphere socalled. The 3D surface of a 4D ball. Or the same set without the ball (throw away the 4D surround and interior and just keep the set.) So yes, it is hard to picture. Glad you tried. It may get easier after a while. Depends on the person.

 

Since the light from the far distant object is not all that far away at an earlier time

the speeds of the far distant expansion should not be an issue as with a closer

proximity expansion. Light from nearby galaxies has no problem getting here. Why

would it be any different ?

 

It still seems that it should exceed the speed of the early expansion and reach us in fairly short order in the distant past.

 

This is an intelligent thought which however is based on a flawed assumption. You assume the Hubble rate back then was comparable to what it is now. So if light started out 40 million lightyears away, it shouldn't have any trouble getting here. You say. Just like light that leaves today from nearby galaxies.

 

But what we talking about is a mathematical model in which the scalefactor a(t) and the Hubble rate H(t) are governed by differential equations derived from General Relativity. And they are highly dynamic. They did not at all stay the same over the course of history! Especially in the first few millions of years.

 

In a mathematical science you make the simplest model that fits the available data and see what it says. You don't make up scenarios and argue them pro and con with verbal reasoning. GR is a theory of geometry which has been tested many times to exquisite precision. For practical purposes it is the only one, if you don't count the newer quantum versions.

 

Well GR says that a roughly uniform universe should be expanding or it should be contracting. So Big Bang cosmology was predicted by Friedman in 1922 without any news about redshifts---just as one of the simplest solutions to Einstein's GR equation.

 

Our dominant theory of gravity, orbits, time-behavior, light curving, etc etc. predicts that the early universe Hubble rate is way way faster than now. So it is not surprising that CMB photons can start out towards us, from a distance then of 40 million lightyears, and take 13.7 billion years to get here. They started out when expansion was 380,000 years old and the Hubble rate was over tenthousand times faster than it is today. (Assuming the General Relativity equation is right.)

 

I wish I could show you Morgan's calculator with the input of z = 1090, the redshift of the CMB. It gives the distance then, distance now, recession rate then, recession rate now. (Recession rate is not a motion speed it is a distance expansion rate.)

 

If you want to try, google "cosmos calculator" and put in the usual parameters 0.27 for matter, 0.73 for lambda, and 71 for today's Hubble rate.

 

... So, I am just attempting to relay what I think is mainstream today. Knowing that much of it will change tomorrow.

...

I think that is a really constructive goal. Unless enough people do that, we won't have a scientific culture---collective understanding will get fragmented IMO.

Edited by Martin
Posted (edited)
..I wish I could show you Morgan's calculator with the input of z = 1090, the redshift of the CMB. It gives the distance then, distance now, recession rate then, recession rate now. (Recession rate is not a motion speed it is a distance expansion rate.)...
I had a couple of extra minutes.

 

 

Edit - Fixed typo on attached image.

martin1.jpg

Edited by NowThatWeKnow
Fix chart
Posted

Thanks! Tell me how you do it, please, if it's simple to do.

In this case there was a typo: the lambda term should be 0.73.

 

Because of observed near flatness the matter term and lambda term always should add up to 1 (or so close to 1 that we don't worry about it, like 1.01).

So that is always a good check. In this case .27 and .23 don't add up.

 

This could be a real asset pedagogically. Hope it doesn't take a long time or offer opportunities to screw up.

Posted
Thanks! Tell me how you do it, please, if it's simple to do.

In this case there was a typo: the lambda term should be 0.73. ...

 

Can you believe all the mind power necessary to come up with the knowledge to make this calculator accurate, and I had a typo that made it all worthless. :eek:

 

Well I fixed it. :D

I will PM you.

Posted

Reply to Martin and NowThatWeKnow .....

 

Thanks for your replies. I have not been able to get on the net

lately due to hardware problems.

 

If I understand what you are saying, the early expansion was

happening at many times the speed of light so that at that time

you probably could not have seen any light all ? Even the light

coming from your own sun ????? I gotta tell ya, I start to get

real skeptical when theories require that kind of speed. My

calculus is really rusty so I'll take your word for the math.

 

Are we sure that the red-shift method is really giving us the

right numbers. I've read many articles that pretend to cast doubt

on it.

 

Do we know whether or not the light wave expansion is due to

acceleration away or could it just be a natural wave expansion

simply from the long trip or a gravitational anomaly or something

else.

 

I posted a blog on this forum about 2 months ago concering light.

It was titled "Is there more to light than meets the eye".

I think it's on Page 3 now.

I was somewhat disappointed that not more people had comments.

I postulated that light completely permeates the cosmos and as a

result space is a vacuum but nowhere near empty. I had read an

article concerning a couple of satellites in distant orbit near

the outer planets that had orbit anomalies that were not as

calculated by scientists. I was wondering if the push it got from

our sun's light to the 'light ether' I speculated on had anything

to do with it.

 

I also wondered if light itself is the driver for universe expansion.

I expected that wherever the limits of the universe where that

light would get there first and finding nothing to stop it would

continue to expand the universe until all the galaxies burned out.

Based on your comments about multi-c expansion speeds I suppose that

idea is history.

 

If you feel like reading it, I would sure appreciate any comments.

Posted (edited)
...the early expansion was happening at many times the speed of light so that at that time

you probably could not have seen any light all ? Even the light

coming from your own sun ????? I gotta tell ya, I start to get

real skeptical when theories require that kind of speed...

 

...Are we sure that the red-shift method is really giving us the

right numbers...

 

...I posted a blog on this forum about 2 months ago concering light.

It was titled "Is there more to light than meets the eye"...

 

...I also wondered if light itself is the driver for universe expansion....

Martin is the expert and I am far from one but I would like to comment on a couple of things you said. The z=1090 I used in the morgan calculator took us back to the big bang when it was thought the expansion was at it's greatest.

http://www.uni.edu/morgans/ajjar/Cosmology/cosmos.html

It very quickly fell off to a much lower speed when the universe was still starless dust and not transparent. I think the largest Redshift seen now is 8.2. Play with the calculator to get a feel for how they think it all went down. I agree with you that the jury is still out.

 

I am not sure exactly how they use the cosmological red shift to determine expansion speed but there are a couple of different methods to cross check the results. The duration of an initial bright phase of a supernova is also used to determine distance and expansion.

 

I often thought that light itself could be the energy responsible for the universe expansion but I have been told there is not enough energy there to produce the results we observe. It made more sense to me then dark energy/matter that we can not detect except for the results it produces. Almost like saying God did it. I will also not be surprised if there is a, yet to be defined, ether discovered with light playing some role.

Edited by NowThatWeKnow
Posted (edited)
... the early expansion was

happening at many times the speed of light so that at that time

you probably could not have seen any light all ? ....

 

That doesn't follow. How about reading a Scientific American article about the basic expansion concepts? You seem not to understand or have some hang-ups on some misconceptions.

 

The Lineweaver article in my sig is a good one. In fact it's so good they use it at Princeton as a kind of supplemental textbook! See where it says "cosmology SciAm" in small print?

 

Distances to most visible galaxies are at present increasing faster than light, but we still see them. The Lineweaver article explains why.

Faster than light expansion of distances is not confined to the early universe.

The fact that it is currently going on today hardly prevents us from seeing the sun :D. So there is something wrong with your reasoning. Somehow you are picturing expansion wrongly so you draw absurd conclusions.

 

I guess the cutoff is z = 1.7. If you spot a galaxy and it redshift is less than 1.7 then the distance to it is increasing slower than c. If the z > 1.7 then the distance is increasing faster. All nearby galaxies, that you can get a good picture of, that aren't just fuzzy blobs, are z < 1.7. But still, since the universe is a big place there are a lot more with z > 1.7. That's why I say that distance increasing faster than c is typical.

 

When you get Charley Lineweaver's article pdf, the first page is blank white, so scroll down. The link works, I just checked.

They have it at princeton.edu too.

http://www.astro.princeton.edu/~aes/AST105/Readings/misconceptionsBigBang.pdf

Edited by Martin
Posted

Reply to Martin ......

 

Thanks for the links to the Scientific American and others.

It offers important help understanding some of the misconceptions.

 

I guess that what was somewhat confusing to me was the balloon

model which represents a sphere. I'm wondering if it might be

more clear to use a cone where the big bang is a slightly rounded

small end of the cone and the current state of the universe is

now a slightly rounded large end (so large as to appear flat) to

any observer. This would still allow for expansion in all directions

with a constantly moving center.

 

It was curious to me that the average density predicts a flat

universe but the expansion would seem to indicate otherwise.

Could it be so nearly flat that we could not detect the curvature ?

Posted (edited)

 

Thanks for the links to the Scientific American and others.

It offers important help understanding some of the misconceptions.

 

I'm glad you had a look at some of those sources. Check out Einstein Online if you have time. It is a public outreach website of one of the world's top research institutions (Germany's network of Max Planck Institutes).

 

I guess that what was somewhat confusing to me was the balloon

model which represents a sphere. I'm wondering if it might be

more clear to use a cone where the big bang is a slightly rounded

small end of the cone and the current state of the universe is

now a slightly rounded large end (so large as to appear flat) to

any observer. This would still allow for expansion in all directions

with a constantly moving center.

 

I'm not sure exactly what you have in mind but the hollow cone or "horn" shape is a common and handy way of picturing the whole expansion history. The whole spacetime. In that case the rudimentary toy-model of space is a 1D circular ring. The time axis is along the cone, and it shows the rings getting larger as you go from left to right.

 

It's a trade-off, including a time coordinate, so the whole history is modeled, means an even more rudimentary representation of space. In the balloon we already simplified by having space be 2D. In the horn picture space is a mere 1D circle, with 1D creatures and objects living in it.

 

Remember that spacetime does not expand. The expansion of spatial distances only. So one does not want to have "expansion in all directions".

One only wants to model expansion in all spatial directions (which takes place in the course of time without time-expansion, whatever that would mean :D)

 

It was curious to me that the average density predicts a flat

universe but the expansion would seem to indicate otherwise.

 

The jury is still out on whether flat or nearly flat. Average density cannot be measured with absolute precision. So far average density says at least it is nearly flat, and possibly flat. But we don't know yet.

 

Could it be so nearly flat that we could not detect the curvature ?
Yes that is a very real possibility. It just means we have to work harder and build and launch better instruments. This month a new orbital observatory goes up---called Planck Surveyor. It will be able to determine the curvature still more accurately than the previous spacecraft, Cobe and Wmap, did.

 

Planck Surveyor launch is set for May 14, which is in three days from today. Keep an eye on the website and wish it luck!

http://www.esa.int/SPECIALS/Operations/SEM45HZTIVE_0.html

http://www.rssd.esa.int/index.php?project=Planck

http://en.wikipedia.org/wiki/Planck_Surveyor

Edited by Martin
  • 4 weeks later...
  • 2 weeks later...
Posted
After reading a number of scientific articles about far distant galaxies and the

estimated age of the universe I began wondering how we could supposedly

see light from objects that are 12 billion light years or so away. This is

supposed to be light from nearly the beginning of time and space.

 

If we agree to believe that the big bang actually happened then this would

mean that at some point we were much closer (cosmologically speaking)

to those distant objects.

 

Since matter travels at a mere fraction of the speed of light is seems

somewhat dubious that any light emitted from that object at the beginning

of time, as we know it, would not already have passed us a long, long, long

time ago.

 

We have developed many tools for measuring distance from relatively

nearby objects. I suspect that these work well up to a point, at which

they start to break down somehow.

 

Could it be that using light to measure distance works well when

objects have been relatively close together since the beginning and

then breaks down when objects become very far apart ?

 

Maybe the big bang never happened and objects that are far away have

always been far away ?

 

Doesn't the fact that these supposed far distant objects are 12 billion light

years away mean that the universe is far older than 14 billion light years

or have these objects been moving at the speed of light ?

 

I found an article in Wikipedia which attempts to explain this but I'm not

sure I buy it. Look for 'Metrical_expansion_of_space'.

 

There are many conflicting Big Bang theories.

Only a theory holding that physical laws have always been the same can the the base of a scientific discussion.

With that hypothesis big bang must have been an explosion at a given moment at a given place.From the actual velocities etc. of stars we can deduce the coordinates of the big bang .The conclusion then is that,depending on the choice of stars, the BB did not occur at a single moment or at a single place, but at several or many different places and times..

 

Another problem is the velocity problem

By hypothesis all initial mass would in one point.By leaving that point the velocities of the stars would decrease by the Newton laws. Considering actual speeds we can calculate the speeds1.000 years ago, .2.000 years ago etc. We then find that,not so long ago, several stars must have had velocities of 2c,3c etc., c being the velocity of light.

Therefore we must conclude the BB never happened

 

Aristotle wrote down the opinion of most Ancient Philosophers : The cosmos was never created, had always existed and had always been varying.

 

Actually the Aristotle theory is the only theory of the origin of the world that is not contradicted by science or religion

  • 2 months later...
Posted (edited)

There indeed are many theories about the origin of the universe. Even though the world doesn’t need another one, I do have my own ideas, as an applied scientist, about it.

 

 

 

post copied to new thread

Edited by swansont
Posted

I'm with you on having trouble understanding using 2-d and 4-d balloons to explain a 3-d problem. Apples and oranges. 2-d balloons and 4-d explanations just don't hack it in this real world of real, existing, galaxies. For example, the 2-d balloon expands but the 2-d material it is made of doesn't. To me, its a simplistic way of explaining the "what is the universe expanding into?" question. apples and oranges.

Posted

If I may butt in to offer a few thoughts.

 

I think they may be valuable to the discussion, because 3 or 4 weeks ago, I posted some ideas on this board, that were soon moved to Peusdo Science and Speculation and I was disturbed, because I thought I had some insights into the nature of the universe, that would change scientist's view of what they were looking at, and spur a whole series of new discoveries. I thought I saw some logical inconsistencies in the current model. I still think I see some inconsistencies, but they are dwindling, and no doubt will continue to dwindle as I learn more, until I see NO inconsistencies and am in agreement with mainstream science, and would then know enough to form a hypothesis that would have a chance of actually being valuable in furthering human knowledge.

 

So here are a few of the mistakes I made.

 

One was a general overestimation of my own insights, and an underestimation of the insights of others (cosmologists for instance.) What I mean by that, is that if I could put two and two together, and be excited about the fact that I realized it COULDN'T be three, and COULDN'T be -16, I was overestimating my own insight in an objective comparison to the insights of those who have the insight that two and two would make four. Those people had already had the "couldn't be three" insight, and many subsequent insights that led them to the insight that two and two is four.

 

My second mistake, was jumping to conclusions, without all the facts. I figured the answer was probably about half way between 3 and -16 and that would put it in the -9 or -10 region. How could mathematicians think it was 4?

 

I am still seeing inconsistencies, but will not mention them here, this is the science section. I need to understand the facts first, before my speculations are anything but distractions from the truth. I mention this as a caution to certain others.

Don't take your conclusions about the universe, based on your own mental model of the universe, as fact, until you have matched "all" the facts we know against your model, to see if it works.

 

Many minds, as nimble as yours and nimbler, have been matching facts against model for many years, and all together have worked a model that fits what we know. Don't underestimate their insights, and don't overestimate your own.

 

On this board the goal is to bring the insights of science to those who have yet to have them.

 

If you would like to share half-baked insights of your own, I will see you in Psuedo Science, where I am sure to be, mucking about.

 

Regards, TAR

  • 1 month later...
Posted

Tar: Not intending to be offensive, but your post seems to boil down to, "Don't interject your opinions in the grown ups conversation; come back in ten or twelve years when you know something." You say not to argue a concept with common logic, but isn't that what virtually every pioneer of science has done since the beginning of trecorded history? They build a model first and then find a way to test it against available evidence.

Those who don't have the immediate math available to them try to mull it out, and even Einstein developed GR through a series of thought experiments trying to compare a constant- the speed of light- to separate observers in different, localized regions, before the proving through the esoteric probing of numbers on paper and black board.

Math, when you get down to it, is a tool we use to attempt to more accurately describe the concepts we're trying to explore, not the perfect lens through which we define new discoveries. Ultimately speaking, my best analogy for what I'm trying to say is that math is the picture we paint of what we're trying to see, not the thing we see itself. Or something like that. I'm drunk and tired and have to go to sleep so I can wake up in five hours.

Just my $.02

Posted

It is my belief that we will never be able to integrate the universe through

mathematics. It is a victim of its own precision. Everything seems to

break down when it approaches zero or infinity. There seem to be levels

of what I like to call relative infinity or relative zero. We are insulated

from these areas and for good reason. Relative infinity is easily less than

1000 light years and any attempt to derive anything of practical value is

probably a waste of time. Our best bet is the near practical zero of

Quantum mechanics which may offer some useful practical applications

for energy production or other scientific use. The single most important

thing for science to discover is whether infinity or nothing (zero) truly

exists in our relatively closed system. Only then will we understand the

unfathomable universe.

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