Starship Asterisk*

Inflation implies a vastly expanded concept of what the universe is. But the concept is also helping us to understand the universe we see around us. Take, for example, the recent observation that the universe is not only expanding—a fact astronomers have known for over seven decades—but actually accelerating outward.

While we can never directly "see" the whole of the universe or glimpse its farthest horizons, we can discover how it is behaving—how fast it's growing, whether its growth will one day come to a halt, and what forces have been driving its evolution on the largest of scales. The evidence for the cosmic acceleration—the observations of distant exploding stars.

Whatever could produce that acceleration? Certainly there is nothing in our Earthly experience that prepares us for such a possibility. This is where the theory of inflation comes into play. Now about two decades old, inflation entertains the idea that there is a kind of energy that causes space to expand. This energy competes with gravity, though certainly not on local scales. However, should this form of energy come to dominate, watch out! While gravity tries to crush, this energy—call it vacuum energy, or the scalar field, or the energy represented by the Cosmological Constant in Einstein's equations describing the dynamics of the universe—tries to expand the fabric of space, pushing everything apart. The basic proposition of the inflation model is that this form of energy once dominated gravity and caused our universe to burst forth.

It turns out that the basic inflation picture satisfies a number of observed facts about the universe. One fact is particularly interesting because the better our observations become the more tightly they agree with a prediction of the inflation model. This is that the universe should be "flat"—no overall curvature of space. Spectacularly convincing evidence—recent measurements of irregularities in the microwave background radiation—supports this proposition.

The theory of inflation predicts a precise recipe of how structure would form from little things merging into big things and tells us how many little things there should be for each big thing. The observations match with expectations if the mix of energy and matter is the same as that suggested by the supernovae experiments. Inflation also solves the old controversy over the Hubble Constant, the relationship between the rate galaxies are flying apart and the distances between them. If the Hubble Constant is large then galaxies are relatively close together and the implied age of the universe is way too short if the universe has been briskly expanding. The universe cannot be younger than things in it. However, if the universe has been loitering and is now accelerating, then it is old enough and a large Hubble Constant is still possible. And we can actually make a direct measurement of the mass density of the universe by looking at the motions of galaxies that slosh in the gravitational wells of the matter. We find something that has come to be called "dark matter" there. If the universe is "flat," then this state is achieved through the sum of the mass and energy density. Measurements of gravity perturbations reveal just the needed complement of matter offsetting the repulsive energy indicated by the supernova measurements.

The last couple of years have seen a remarkable convergence of evidence, all suggesting that we live in a universe with a few percent of the normal matter of our everyday experience, maybe 25% of something called "dark matter," which is a name given to hide our ignorance of what it is, and 75% of this energy that wants to push space apart—call it "dark energy." If true, then relatively recently in the history of the universe the "dark energy" has become dominant over "dark matter." During the transient dominance of dark matter, it caused the collapse into all the structure of the universe that we have come to know and appreciate.

Qev,

John Dobson's "Beyond Space and Time" available several places on the web.

I happen to have his book right in front of me!

He is talking about how we measure distances, and uses the analogy of two ships captains, one using polar north and the other using magnetic north, to plot their courses between two islands. They take different paths, (two frames of reference) to get there and have different numbers for the separations in terms of NS and EW dimensions of the triangles, but they both agree on the distance between the two islands. If the islands are several thousand miles apart it becomes a 3 dimensional problem, not two as when they are close together. OK

Now I'll quote a couple of pages to layout what he is saying.

"For a three-dimensional space the equasion of separation between two points becomes
D=(square root sign) X^2 + Y^2 + Z^2
where the directions X,Y and Z are taken perpendicular to each other.
Suppose we want to measure the distance diagonally across a room from the southeast corner at the floor, to the northwest corner at the ceiling.
If the walls and the floor are perpendicular to each other, we simple have to measure along the base of one wall to the far corner, then along the base of the far wall and, finally up the corner to the ceiling. These distances will be our x, y, and z in the equasion, to find the distance.

"But the world is not objective in three dimensions either. We live in a Universe of four dimensions, and, as Einstein pointed out in 1905, time also must come into this equasion if the equasion is to remain invariant for observers moving with respect to each other. Our problem is not how to measure from the southeast corner at the floor to the northwest corner at the ceiling, but rather, how to measure the total separation, the four-dimensional separation, between an event at one of those corners and another event at the other. [like further out in space between stars]

"Our difficulty arises because the distance alone turns out not to be objective. That is, two people moving with respect to each other measure different distances between those events. Also, the time separation between two such events is not objective. Observers moving with respect to each other disagree on the length of time that has elapsed between two events. Only four-dimensional addresses such as here-now and there-then are objective, and the separation between any two such addresses(events) is also objective.

"Here, "moving with respect to each other" corresponds to our two ships' captains choosing different coordinate systems, i.e., choosing different directions along which to measure north or east. Just as our ships' captains differed in their estimates of the distances north and east to the second island, just so, two observers moving with respect to each other might differ in their estimates of the space and time separations between two events. But just as our ships' captains agreed on the total distance between the islands, just so, our two observers, moving with respect to each other, will agree on the total separation between any two events.

"Einstein's equasion of separation takes the form;
S = (square root sign) X^2 + Y^2 + Z^2 - T^2

"We write S instead of D because the four-dimensional separation is no longer simply a distance between here and there, but rather, a space-time separation between here-now and there-then.

"Now S is invariant, that is, if we agree to measure the distances x, y, and z in the same units and the time, t, in a corresponding unit, then the separation, S, between any two events will be seen to be the same to all observers regardless of their states of motion with respect to each other. S is invariant, i.e., it is objective. It is the same for all observers regardless of their motion or their points of view.

"(Einstein never liked the term relativity theory. He wanted it called the theory of invariants.)

"This, then, is our new geometry designed to save the objectivity of the Universe. But does it? For any two events, say here-now and there-then, this equasion can be simplified to;
S = (square root sign) X^2 - T^2

"So long as the x direction is chosen from here to there or from there to here, so that y and z are zero.

"It should be noted that time comes into this equasion as MINUS T^2, so that if one observer sees a greater distance, x, between two events, he will also see a greater time, t. Between the events here-now and there-then, one observer will see a greater distance between here and there and a greater time between now and then. It is only the total separation, S, that is objective, or invariant.

"SPACE AND TIME AS OPPOSITES

"With the equasion of separation in this form,
S = (square root sign) X^2 - T^2, it becomes immediately obvious that space and time are opposites because where x and t are equal,
S=0.
That is, for the events here-now and there-then, if the space separation between here and there is equal to the time separation between now and then, then the total separation between here-now and there-then is zero.

"Under what conditions is it true that the total separation will be zero? Is it simply a trivial case? No, it is by no means trivial, because it is true for any two events one of which can be seen from the other. If what we call a light beam can go from the event there-then to the event here-now, or from here-now to there-then, then the events must be considered adjacent, that is, the total separation between them must be zero. It is true for every event of our perception. The separation between the event of perception and the event perceived is zero. We see the whole Universe in the past. We cannot see anything when it happens. We can't see the back of our hands when we hold them at arms length, in the now. We see everything late. Every event that we see as away from us in space we see backwards in time, and it is only on the basis of such perceptions, where the separation between the perceiver and the perceived is zero, that we have come to the conclusion in the first place that the Universe exists outside.

"The ancients used to say the "the mind goes out through the eye and takes the form of a pot." The moderns say that "the photons come in from the pot and take that form in the eye." The equasion says that it makes no difference which mistake we make -- the separation is zero. In an effort to save the objectivity of the Universe, we have had to abandon the separation between the perceiver and the perceived.

"The Universe which we see is set up in this very peculiar way so that we cannot see anything when it happens. We see the whole show in the past. If we see an event in the Andromeda Galaxy at a distance of two and half million light years from us, we see it two and a half million years ago. Why? Usually we say that is because light travels at a finite velocity. But really, of course, it is because what we call the speed of light is simply the ratio of space to time. One light year is equal to one year. And we see a Universe as if outside of us by this elaborate trick of seeing everything as back in time, and in just such a way that the total separation between the perceiver and the perceived remains zero."

===

Now I am not seeing that all of this is shedding any light on the previous postings problems of redshift being connected to time dilation. It rather proves the case for redshift to be connected to time dilation.
So I stand corrected ! Thanks Qev !
It is more of a tangential subject of philosophical inquiry in regards to perception in general.

One of Dobson's pet peeves is "there are no Photons ! " There is nothing bebopping all over the place in the 'all possible probabilities' in a 'sum over histories' fashion to account for the observed behaviour of light.
There is nothing that goes from there-then to here-now, that we call photons, because the space-time separation between the observer and the event observed is zero. If there were photons, spacetime would be so clogged up and filled in every possible history of path of traverse, we couldn't force our way through them all to cross the room. haha

There is something we are missing, and keeping our noses to the grindstone of photons is limiting our seeing the truth of the universe and the essential nature of existance. Dobson doesn't claim to have the ultimate knowledge of the Universe, but he points out some very important mis-takes we are making in our western sciences. He is an important voice in the search for reality and its underlying causes and forces. But of course mainstream science is ignoring him as he is not in accordance with their ideology.
This is not the only earth shaking illumination he has in his book, but it is better if you hear it directly from him rather than through the lens of me.

kovil wrote:Qev, quintillion electron volts e^37! goodness gracious

Well, it was approximate...

That's interesting data, that high redshift supernovas have a longer time duration. That is the data, I prefer to leave it an open question as to why, rather than to immediately say it is because of thus and such.

Let's for a minute presume, that the supernova was of the same time duration as normal, in its location where it is happening that is. But we see it redshifted and taking a longer time to happen. This is curious to me, as I would not expect that a redshift would translate into taking longer to unfold the events, as watching a movie is a slower motion playback. Light speed is constant! It should unfold in 'realtime' !! even tho it is redshifted. Are other high redshift objects thought to be slower in time 'playback' mode ?
Meaning that the light and time are out of synchronization.
Whereas in 'normal' space-time, light goes at the speed of time, so to speak, and when the light arrives is when it happened, according to the light !!! that is.

The speed of light, as far as we can observe, is a constant, and this is a key point of Einstein's theories. Because the speed of light is constant for all observers, this leads to a weird thing: space and time are not constant for all observers. Depending on our relative velocities, we may see the same event unfold differently, we might measure distances or masses differently, and we'll even find our clocks no longer match up if they started synchronized. Relativity is a wonderful, bizarre, and powerful theory.

Cosmological redshift actually means several things. The reason light is redshifted, under current theory, is due to the velocity at which the objects are receeding from us because of the expansion of the universe. This basically 'stretches out' lightwaves emitted by the source, dropping them to lower energy from our point of view.

Thus, a higher redshift means the object is receeding from us faster. According to relativity, the faster an object is moving relative to us, the slower we perceive time passing for that object; we call this time dilation. This is why the distant supernovae appear to take longer than nearby ones: they're moving away so quickly from us that, from our point of view, their clocks are running slow, time has slowed down for them.

Astronomers tie redshift to distance via the Hubble expansion; the more space there is between two objects, the more that space is expanding in a given length of time, which means the further apart they are, they faster they'll receed, which of course means a higher redshift. They of course use other measurements to try to confirm this as well, such as the brightness of distant supernovae and observations of variable stars.

This leads into the explanation that Dobson speaks of;
That the SpaceTime separation between the event and an observer is ZERO.
This does not mean that there is no time or space separating the observer and an event observed; but that the Total SpaceTime Separation between an event and the observer is Zero.

It took me a while to understand what he meant by that too.
Like about 3 years !

I hope you won't ask me to explain it as it seems to not make sense now.!

I'll have to admit it doesn't make much sense to me. Perhaps you could point me to a link of his work? I'm curious, though I tend to take a grain of salt with any theories that claim an overthrow of General Relativity... it's way too well backed up to be knocked over by anything but the most overwhelming of evidence.

Qev, quintillion electron volts e^37! goodness gracious

That's interesting data, that high redshift supernovas have a longer time duration. That is the data, I prefer to leave it an open question as to why, rather than to immediately say it is because of thus and such.

Let's for a minute presume, that the supernova was of the same time duration as normal, in its location where it is happening that is. But we see it redshifted and taking a longer time to happen. This is curious to me, as I would not expect that a redshift would translate into taking longer to unfold the events, as watching a movie is a slower motion playback. Light speed is constant! It should unfold in 'realtime' !! even tho it is redshifted. Are other high redshift objects thought to be slower in time 'playback' mode ?
Meaning that the light and time are out of synchronization.
Whereas in 'normal' space-time, light goes at the speed of time, so to speak, and when the light arrives is when it happened, according to the light !!! that is.

This leads into the explanation that Dobson speaks of;
That the SpaceTime separation between the event and an observer is ZERO.
This does not mean that there is no time or space separating the observer and an event observed; but that the Total SpaceTime Separation between an event and the observer is Zero.

It took me a while to understand what he meant by that too.
Like about 3 years !

I hope you won't ask me to explain it as it seems to not make sense now.!

The Universe is all, that goes for ever. Its a word, it cannot be expanded, twisted, compacted, add dimensions as in multi and so on.

But! its home for all the internal parts that can be expanded ,twisted, bent, compacted and so on.

The general process of the internal parts of the universe is the process of recycling. One only has to so Active Black Holes in sucking and ejecting material, star formations and exploding and reforming. The formation of the elements within the star and during the explosion of the star.


As for the Big Bang creating the all Universe is so out of place. One only has to look at the Deep Field images 13.2 Billion light years away to see existing galaxies. Thats in one direction and similar in opposite directions. Simple maths can tell you that the BBT does not add up. Yes I know about redshifts and WMAP measurements an so on. Take these with a bit of salt.

Man through history has put himself in the centre. Earth is just a dust partical of a dust partical.

We have gained extra ordinary knowledge within the last 50 years and yet some of us are trapped within our limited knowldge.


Its only now that I know that I do not know much at all.

kovil wrote:Respectfully Qev,

I disagree strongly with your analysis.

Well, I don't really know enough about it to analyze it myself. I just mostly agree with Big Bang theory, 'cause it seems pretty consistent and well backed up.

Redshifting light does not blur the sharpness of the information the light is carrying. So it's interaction with whatever is causing the redshifting to happen is not bluring the information. We still are not certain how it is being redshifted other than recessional velocity, but there are things pointing to the fact that it is happening. Which sadly is not being investigated enough.

The problem is that any physical interaction that can take energy away from photons, to my knowledge, must scatter them. I think the 'tired light' theories rely on Compton scattering, and it's been proven there that it can't work. I agree, though, that any reasonable theory for an effect should never be dismissed without investigation. To do otherwise is just bad science!

What do you mean by "relativistic time-dilation effects" ?
The light we see happened that long ago in distance, do you mean that our measure of the distance, by the age of the light is out of synchronization to the age of the light?

Well, the best example is this: a supernova event takes a given length of time, I'm not sure what the average length of a supernova is, let's say 20 days for the primary event. Nearby supernovae with low redshifts take roughly that long from our point of view. However, supernovae at high redshifts appear to have much longer durations, which implies that they're receeding from us at relativistic velocities. We're seeing time-dilation in action. If the redshifts aren't due to recessional velocities, then we wouldn't see this effect.

However I do not agree that the universe is "expanding, causing there to be 'more space' between distant objects".
For if the universe was expanding to create 'more space' between objects 'over there'; it would also be equally expanding to create 'more space' between objects 'over here' !! And we are not experiencing 'more space' being created 'over here' ! Are we ? !

Sure we are! However, this expansion only really becomes significant over cosmological distances. At short ranges, gravity easily overpowers its effects, keeping things like planets, solar systems, galaxies, and galaxy clusters gravitationally bound.

We are NOT at the center of the universe.

We are however, at the center of our awareable universe; the portion of the universe we can be aware of, that portion of the universe which light will reach us from.

Well, yes, by definition we have to be at the center of our observable universe, as we can generally see the same distance in all directions. But that's the only 'center of the universe' that has any meaning... it doesn't have any 'real' center. Every point in the universe is as equally its center as any other.

I agree with this; in the sense of "their light will never reach us."
I expect we disagree about the why their light will never reach us;
but hey , that's cause we exercise our rights of free speech !!

Viva la free speech !

I concur! We don't have to agree with each other's arguments, but be darned if I'm gonna say you can't make them.

Keep posting Qev, I like to hear views different from my own.

Thank you! You too! Open discussion is the best way to find new ideas.

How many electron volts is a Qev ?

Something on the order of 5.224140924e+37 electron volts or so. Give or take.

The Virgo Supercluster of galaxies, in which our galaxy is part of, is not at the center of the observable universe. -I don't care whose eyes you borrow to view the night sky.

Respectfully Qev,

I disagree strongly with your analysis.

<<Any interaction of the light from distant sources with the intergalactic medium, that was strong enough to create the observed redshifts, would also blur the images of said distant objects into unobservability, which is most certainly not what we observe. >>

Redshifting light does not blur the sharpness of the information the light is carrying. So it's interaction with whatever is causing the redshifting to happen is not bluring the information. We still are not certain how it is being redshifted other than recessional velocity, but there are things pointing to the fact that it is happening. Which sadly is not being investigated enough.


<<We also see relativistic time-dilation effects proportional to the redshifts of distant objects, so 'tired light' fails there, as well. >>

What do you mean by "relativistic time-dilation effects" ?
The light we see happened that long ago in distance, do you mean that our measure of the distance, by the age of the light is out of synchronization to the age of the light?

<<The universe doesn't expand into anything. All space everywhere is expanding, causing there to be 'more space' between distant objects as time goes on. >>

I agree with you that the universe is not expanding into anything beyond itself as the BBT expansion postulates. I grasp that idea and agree with it.

However I do not agree that the universe is "expanding, causing there to be 'more space' between distant objects".
For if the universe was expanding to create 'more space' between objects 'over there'; it would also be equally expanding to create 'more space' between objects 'over here' !! And we are not experiencing 'more space' being created 'over here' ! Are we ? !

We are NOT at the center of the universe.

We are however, at the center of our awareable universe; the portion of the universe we can be aware of, that portion of the universe which light will reach us from.

<<There are regions of the universe, . . . , that we will never be able to observe, as they are retreating from us so quickly that their light will never reach us.>>

I agree with this; in the sense of "their light will never reach us."
I expect we disagree about the why their light will never reach us;
but hey , that's cause we exercise our rights of free speech !!

Viva la free speech !

Keep posting Qev, I like to hear views different from my own.

How many electron volts is a Qev ?

Kovil

----------------
I managed to get some of the 'hair of the dog',
but the rest of it got away. ~!

A lot of the arguments used on these sites to dispute the Big Bang are rather... flawed, or don't take into account modern data, like the WMAP measurements of the inhomogenities in the cosmic microwave background.

The 'tired light' theories also don't work terribly well. Any interaction of the light from distant sources with the intergalactic medium, that was strong enough to create the observed redshifts, would also blur the images of said distant objects into unobservability, which is most certainly not what we observe. We also see relativistic time-dilation effects proportional to the redshifts of distant objects, so 'tired light' fails there, as well.

The universe doesn't expand into anything. All space everywhere is expanding, causing there to be 'more space' between distant objects as time goes on. This is unlike the expansion of objects we're familiar with, like an explosion, and is rather... peculiar to try to picture in one's mind.

It's definitely true that we are limited in what we can see of the universe; the speed of light is finite, so we can only observe those regions who's light has had time to reach us. There are regions of the universe, assuming the Big Bang theory is accurate, that we will never be able to observe, as they are retreating from us so quickly that their light will never reach us.

Hello


When we look at the expansion of the Universe one needs to question first the Big Bang secondly the red shifts and thirdly the expansion of the universe.

We see just see probably about 13.2 Billion light years into deep space.
This is a sand partical on the scope of "ALL". Man has put his own limits by the small amount of evidence.

Think of it this way. If the Universe is all and unlimited with respect to time and space. How can it expand? Within itself or out of it self? The Universe is not an object it is "All" that is home to many parts. Those parts can grow , explode, shrink, collide, recycle and so forth.

Unless man has defined the known Universe as the extent of what he can see. With respect to what we can see the Uinverse is not expanding.
http://redshift.vif.com/JournalFiles/V1 ... 0N1ANT.pdf
http://www.bigbangneverhappened.org/
http://www.newtonphysics.on.ca/BIGBANG/Bigbang.html

http://www.rense.com/general53/bbng.htm
http://www.newtonphysics.on.ca/UNIVERSE/Universe.html
http://www.newtonphysics.on.ca/hydrogen/
http://ourworld.compuserve.com/homepage ... xplode.htm
http://www.electric-cosmos.org/arp.htm
http://www.setterfield.org/staticu.html

Martin wrote:Someday when we have the technology to map our entire observable universe we will be able to rewind the time-line of matter to a specific region of space. This will give us the exact vicinity/center of the beginning of all matter -in our observable universe.

However, the universe as a whole may encompass multiple universes and possibly extra dimensions as well. Without seeing “all” we will never find a center (“center” implies it’s definable). But as far as our little spot in the known observable universe –it is entirely feasible.

The problem there is... we already ARE at the center of our observable universe. If we 'rewound the movie' of cosmic expansion, then everything we see would come rushing back in on US. Wherever we happen to be. There isn't any spot in any region of the universe that can be considered a 'beginning of matter' for that region. It was all created everywhere, and spacetime itself was created along with it.

It's an isotropic expansion. No matter where you are, everything appears to be moving away from you. No matter where you are, if you run it backwards, everything appears to converge on you. It's weird, but that's how it works.

Must I educate you further?

There is a difference between the universe and the observable universe. See definitions below:

Observable - able to be seen or detected.

Universe - the totality of all matter and energy that exists in the vastness of space, whether known to human beings or not.

As I was saying …….

Remember that the rate of expansion is proportional in all directions. To find a center to the universe is an unrealistic question however, locating the center of the observable universe is feasible. Matter/energy came from the same point as the BBT goes.

Someday when we have the technology to map our entire observable universe we will be able to rewind the time-line of matter to a specific region of space. This will give us the exact vicinity/center of the beginning of all matter -in our observable universe.

However, the universe as a whole may encompass multiple universes and possibly extra dimensions as well. Without seeing “all” we will never find a center (“center” implies it’s definable). But as far as our little spot in the known observable universe –it is entirely feasible.

makc wrote:

Martin wrote:locating the center of the observable universe is feasible.

sure. it's in observer's eye.

You beat me to it. I was going to wave at him from the center of the observable universe. Well, my observable universe.

Martin wrote:locating the center of the observable universe is feasible.

sure. it's in observer's eye.

Remember that the rate of expansion is proportional in all directions. To find a center to the universe is an unrealistic question however, locating the center of the observable universe is feasible. Matter/energy came from the same point as the BBT goes.

Confused wrote:Thank you, Qev; your explanation and comments are more useful for me at least.

Happy to help! I'm never sure if my explanations are actually clear, or just making things worse.

The subject of the center of the Universe is something I am curious about. It is my understanding that there is a relative location from which nearly all galaxies are moving away from. What can we see there? I realize that we probably cannot see much there; we have difficulty just seeing the center of our own galaxy.

Actually, that's the trick, and kind of what I've been trying to explain. There is no 'center' to the universe that everything is expanding away from; the expansion will look the same no matter where in the universe you're located; distant galaxies will always appear to be moving away from you. This is called 'isotropic' expansion (you'll probably hit that phrase on cosmology websites a lot).

Another way to look at this, I suppose, is that since all space and time was created at the same point in the Big Bang, everywhere can be considered the 'center of the universe'.

Again, the closest analogy I can come up with is asking something like, "Where is the center of the surface of the Earth?" There isn't one; you can't call any point on the surface of a sphere 'the center'. The universe is the same sort of way, only with more dimensions (you could call it the surface of a hypersphere).

I am also interested in knowing the shape of the Universe, if that is known. We know that (most?) solar systems and galaxies are disc-shaped. Is the galaxie also disc-shaped, or is it more of a globe? Perhaps that question is not relevant to the Universe, but as best as I understand things it is a relevant question. I should create a new discussion for that, instead of hijacking Nick's.

The 'shape' of the universe is kind of bizarre to try to imagine, even moreso than the whole 'center of the Big Bang' issue. It's difficult to assign a shape to something that's quite possibly infinite in extent. Usually when people talk about the 'shape of the universe', they're referring to the overall curvature of space-time. Here is a Wikipedia article discussing the whole thing; I don't trust myself to be able to make sense of it.

Thank you, Qev; your explanation and comments are more useful for me at least.

The subject of the center of the Universe is something I am curious about. It is my understanding that there is a relative location from which nearly all galaxies are moving away from. What can we see there? I realize that we probably cannot see much there; we have difficulty just seeing the center of our own galaxy.

I am also interested in knowing the shape of the Universe, if that is known. We know that (most?) solar systems and galaxies are disc-shaped. Is the galaxie also disc-shaped, or is it more of a globe? Perhaps that question is not relevant to the Universe, but as best as I understand things it is a relevant question. I should create a new discussion for that, instead of hijacking Nick's.

If the image that is being discussed here is intended to include time as a factor, then the diagram seems to be only for very knowledgeable astronomers (and physicists?) and amatures such as I should not try to understand it. I sure did not try to understand it when i saw it originally. The subject of the center of the universe is much more interesting for me, so that is what caused me to get involved in this discussion.

Confused wrote:The APOD image (APOD: 2006 March 23 - Inflating the Universe) that is the subject of this discussion is definitely confusing for me. It is confusing because the Explanation does not match the image. The Explanation does say that the diagram "traces the 13.7 billion year" .... "history of the Universe" but the Explanation does not explain the diagram any further than that; it has related comments, but it does not explain the diagram. I assume the explanation is useful for those people that already understand the diagram and don't need an explanation, but for people that need an explanation, the explanation does not help.

In particular, the explanation sure does not say the things you have said here; more specifically, the explanation does not say that the Universe is a four-dimensional object.

I am not aware of ever reading anything that says that the Universe is four-dimensional in a manner that we cannot understand. I have read comments indicating that the Universe is as three-dimensional as our solar system. I have read an explanation in APOD of an image saying that the image is of an object very, very far away on the other side of the Universe. It seems highly inconsistent to say that we can see an object on the other side of the Universe but there is no center of the Universe that we can ever see. Another comment I have seen is that the Universe is expanding at a slightly increasing rate.

I think a lot of the problem comes from trying to represent the universe, as a four-dimensional structure (ie. three spacial dimensions plus one time dimension) in a two dimensional medium, ie. a flat piece of paper. In the example of the Big Bang timeline image recently posted on APOD, they've simplified matters by removing two of the spacial dimensions. So the horizontal axis denotes the passage of time (increasing to the right), and the vertical axis denotes the relative degree of expansion of the universe in space (ie. increasing width corresponds to greater expansion).

Regarding the WMAP image, it's not so much something 'on the other side of the universe' as it is something very far back in time. Since the speed of light is finite, we can look back in time by looking at objects that are very far away. What the WMAP image is showing is more-or-less the after-image of the Big Bang (or rather a period shortly after it, about 380000 years). Bear in mind that the Big Bang happened everywhere in the universe; the light from the 'nearby' parts of it, however, has already 'gone past us'. But if we look out far enough, we'll see the light from it from regions so far away that is only now just reaching us. That's the Cosmic Microwave Background that WMAP sees.

An interesting bit of trivia, the term "Big Bang" was actually coined in a derogatory sense by opponents of the theory, but it got associated with the theory and kind of stuck. It creates a somewhat incorrect image, as the Big Bang wasn't really an explosion of the type we're familiar with. It isn't an explosion of matter and energy expanding into an already-existing empty space - space and time themselves were created in the event, and are expanding along with the matter and energy they contain.

Recent evidence does seem to indicate that the expansion of the universe is actually increasing in rate, which probably surprised a lot of scientists. No one is quite sure why this is happening; most theories involve a new sort of field or energy pervading the universe, often called Dark Energy or Quintessence, that drives this accelerating expansion.

A bizarre place, our universe.

kovil wrote:What helped me was to start at the bottom of the pyramid of information (data, knowledge) and also get a wholeistic view of the entire thing, so as to see where it goes, so I'm not blindly following my nose and getting lost by looking at too small a things, and missing the big picture.

I think the bottom of the pyramid is very confusing. I prefer to start at the top, or at least as high up as possible. It is near the top that the wholeistic view and big picture exists. So one of us is confused, either you meant to say that you try to start tat the top, not the bottom, of the pyramid or I am Confused.

kovil wrote:Part of the problem is in not knowing what you do know and what you don't know.

Yes, and I hope you will clarify what it is that you know to be factual because there is sufficeint proof and what you are theorizing.

kovil wrote:The idea that it began with a bang, in a new place, infers there is an outside edge that is expanding away from what happened initially.

Either that is totally clear or totally unclear. Your description here, that there is outside edge expanding outward, seems very clear from many past experiences here on Earth, yet you say it as if it is a new concept. That confuses me.

kovil wrote:That edge is what the WMAP is looking towards.

This is where the explanation is not an explanation. Either the edge is such a new concept that many of us need a more thorough explanation, or it is something that we understand very well and the only confusion is that it is presented as if it is difficult to understand.

kovil wrote:It is this side of that edge, but is much closer to it, than we are here..

Huh?

kovil wrote:In speaking of dimensions, we see three physical dimensions and a fourth dimension of time. (that's what that old phrase of "You can't get there from here." means; you can't get to somewhere in the past from now..

Again, either these are concepts that are totally clear yet discussed here as if they are difficult to understand, or there should be more of an explanation. Are you certain that we can't understand it? If so, then say so clearly. You might not be able to make the theory any clearer, but you can at least be more clear when you say that the theory cannot be clearly explained.

My guess is that we can clearly understand the fourth dimension, time, and you are trying to make it more interesting by saying it is not clearly understood.

kovil wrote:One of the problems with Cosmology is, it is a subject we have no gentic programing to understand.

I don't know what gentic programing is.

kovil wrote:We know to run away when scared by a big animal or danger, but we don't know how to visualize a Universe expanding in a dimensional way.

I think you are intentionally confusing. If the fourth dimension is time then we can understand.

kovil wrote:So don't be upset if it is not readily comprehended, continue on with that idea on hold until later; and keep working at getting the idea of OK it expanded somehow in a way I don't yet grasp.

I think you are saying that we don't understand so that you don't have to admit what you don't understand.

kovil wrote:The 'other side of the universe' means the furthest we can see.

That is not my definition. An inability to see the other side does not make it non-existant.

Are you someone that claims that there are new planets in the universe because the planets were never seen before?

kovil wrote:The 'center of the big bang' means, where it happened, and we don't know where that was. So it is simply a reference term, not a literal specific place we can look towards. It is a theoretical place, not a real place.

If it is your belief that nothing exists unless we can see it, then I sure disagree.

kovil wrote:View BBT as a thought experiment, and allow it to exist as an hypothesis in your mind. Something that is not actually able to be known, but very interesting to think about, and ponder.

That is the scientific way, and more scientists should consider the BBT to be more of a theory than they do. I suspect that the BBT is more of a theory than most non-astronomers are told but there are a few astronomers and the media that prefer to assume that the BBT is not a theory.

kovil wrote:The collecting of data is the key. Accurate data is essential to understanding what is really happening out there. Drawing conclusions and making theories is a slipery slope, and every 500 years Science throws away a lot of theories ! So take theories with a "sack of salt". Take data as the foundation of your pyramid.

I sure agree. I think that my skepticism is healthy.

kovil wrote:As for the Universe expanding at an increasing rate, this is all conjecture and theory, so view it as such. Do not think of it as data.

Yet it is my understanding that the data is very strong; about as strong as the evidence that supports the BBT.

kovil wrote:The WMAP is data, and it will be interpreted by different theories very differently as to what it means and what it is telling us about the universe.

I would like to understand it better.

kovil wrote:To be able to think, one technique is to separate the variables from the non-variables. Start your plan with what you know to be firm.

Yes, and therefore it will be especially helpful if you can be clear about what it is that you say that is known to be true and what is theoretical.

Dear Confused,

In contemplating your confusion it is likened to my own beginings when first getting a computer. How do I understand and get this thing to work. It is still a learning curve 7 years later.

What helped me was to start at the bottom of the pyramid of information (data, knowledge) and also get a wholeistic view of the entire thing, so as to see where it goes, so I'm not blindly following my nose and getting lost by looking at too small a things, and missing the big picture.

Part of the problem is in not knowing what you do know and what you don't know. So if I may, we can walk thru it and around it for a double view, inside and outside, then you'll hopefully have a better concept of what you are dealing with.

May I abbreviate Big Bang Theory, BBT.
BBT says the Universe began with a bang, but the bang was in a place that was new. It expanded and as it cooled matter began to form and after a while it started to look like it does now, galaxies and stars and lots of space in between them. The idea that it began with a bang, in a new place, infers there is an outside edge that is expanding away from what happened initially. That edge is what the WMAP is looking towards. It is this side of that edge, but is much closer to it, than we are here.

Now for a different perspective. In speaking of dimensions, we see three physical dimensions and a fourth dimension of time. (that's what that old phrase of "You can't get there from here." means; you can't get to somewhere in the past from now. Like when Willa Cather, the author, went back to her hometown. In 1923 she went to Indiana? where she grew up as a child in the 1870-80's , but it was gone !! Times had changed, horses were replaced by cars, and society had moved on. The change was so dramatic, it was like the place where she grew up had vanished from the face of the Earth) She couldn't get there, from her here.
So the fourth dimension, Time, really is a dimension! Tho I don't usually think of it like one.

One of the problems with Cosmology is, it is a subject we have no gentic programing to understand. We know to run away when scared by a big animal or danger, but we don't know how to visualize a Universe expanding in a dimensional way. So don't be upset if it is not readily comprehended, continue on with that idea on hold until later; and keep working at getting the idea of OK it expanded somehow in a way I don't yet grasp. Part of the problem is our language has poor or no terms to convey what the speaker means precisely. The 'other side of the universe' means the furthest we can see. The 'center of the big bang' means, where it happened, and we don't know where that was. So it is simply a reference term, not a literal specific place we can look towards. It is a theoretical place, not a real place. The BBT is a "thought experiment" , like figureing how long it would take to get to the nearest star in a spaceship. That is an exercise with lots of variables, and no real answer, as we have no way to do that ! yet. A thought experiment.

View BBT as a thought experiment, and allow it to exist as an hypothesis in your mind. Something that is not actually able to be known, but very interesting to think about, and ponder. Yet unlikely we will ever know the definitive answer to.
Tho I do find solace in thinking I have found the Holy Grail and have drunk from it the Knowledge of the Universe; with the Dobson explanation of how all this is fitted together. It is only an idea of all this, but it feels right and that is all that matters. We create our inner reality and live in that for our lives. And if you find one that is comfortable and makes sense to you, that is the best we do in life. As the purpose of Life; is to Live !!
Then there is the external reality, which is not exactly as fungible or organizable as our inner reality is; so we deal with that in repeatable experiments by science. The collecting of data is the key. Accurate data is essential to understanding what is really happening out there. Drawing conclusions and making theories is a slipery slope, and every 500 years Science throws away a lot of theories ! So take theories with a "sack of salt". Take data as the foundation of your pyramid.

As for the Universe expanding at an increasing rate, this is all conjecture and theory, so view it as such. Do not think of it as data. That will help reduce confusion. The WMAP is data, and it will be interpreted by different theories very differently as to what it means and what it is telling us about the universe.

One of the most important aspects of being able to actually "think" ; and they do not teach "how to think" in school, they teach stuff to remember.
To be able to think, one technique is to separate the variables from the non-variables. Start your plan with what you know to be firm. Then deal with the changeable parts as the plan progresses.
Another way is to list what is known to be true, separated from what is suspected to be true, from what is known little about.
We are here on Earth. We see the sky and the lights in it. A spectrograph displays unique aspects of what is going on within the light. We see moons and planets orbiting around the sun, but it is still a mystery as to exactly why they behave as they do. Data vs theory. Focus on the data. Allow the theory to float as a variable, separated from the data.
Theories come and go like leaves from a tree as the years pass, but the tree, that is data and is there for many seasons, if not forever, so to speak.

Kovil

ask more; specific questions as you like.

The APOD image (APOD: 2006 March 23 - Inflating the Universe) that is the subject of this discussion is definitely confusing for me. It is confusing because the Explanation does not match the image. The Explanation does say that the diagram "traces the 13.7 billion year" .... "history of the Universe" but the Explanation does not explain the diagram any further than that; it has related comments, but it does not explain the diagram. I assume the explanation is useful for those people that already understand the diagram and don't need an explanation, but for people that need an explanation, the explanation does not help.

In particular, the explanation sure does not say the things you have said here; more specifically, the explanation does not say that the Universe is a four-dimensional object.

I am not aware of ever reading anything that says that the Universe is four-dimensional in a manner that we cannot understand. I have read comments indicating that the Universe is as three-dimensional as our solar system. I have read an explanation in APOD of an image saying that the image is of an object very, very far away on the other side of the Universe. It seems highly inconsistent to say that we can see an object on the other side of the Universe but there is no center of the Universe that we can ever see. Another comment I have seen is that the Universe is expanding at a slightly increasing rate.

Confused wrote:Of course. If a balloon is simulated as a two-dimensional surface then of course it would not look right.

A balloon is not two-dimensional. I am not an astronomer, but I sure don't understand that the universe is two-dimensional. Do real astronomers really consider the universe to be two-dimensional? If the universe is actually three-dimensional then it would be impossible to find the center when it is viewed as two-dimensional.

Well, the universe is most certainly not two-dimensional. My description there was pure analogy. It's impossible for humans to imagine a four-dimensional object (try it sometime ), so when scientists work with things like this, they'll often simplify by removing extra dimensions.

The two dimensional surface of the balloon represents the four-dimensional spacetime of the universe. The expansion is similar to how the skin of the balloon stretches when the balloon in inflated. If you were 'in' the universe represented by the skin of the balloon, you'd see all the 'galaxies' (ink dots) moving away from you in the same way we see galaxies moving away from us here in the real universe.

Qev wrote:Basically, imagine the entire universe has been simplified down to the two-dimensional surface of a balloon.

Of course. If a balloon is simulated as a two-dimensional surface then of course it would not look right.

A balloon is not two-dimensional. I am not an astronomer, but I sure don't understand that the universe is two-dimensional. Do real astronomers really consider the universe to be two-dimensional? If the universe is actually three-dimensional then it would be impossible to find the center when it is viewed as two-dimensional.

Kind of like the "asteroids" videogame universe... your spaceship flies off the left side of the screen and re-appears on the right side of the screen.

I've always liked the balloon analogy, although it's just an approximation.

Basically, imagine the entire universe has been simplified down to the two-dimensional surface of a balloon. You can draw dots all over the surface of the balloon with a marker, and we can pretend those are galaxies. Now if you blow up the balloon, you'll notice that ALL of the dots (galaxies) are moving away from each other; the skin of the balloon is expanding between them. You'll also notice that you can't find the center of the surface of a balloon, because there's no such place.

That's a very rough approximate analogy to cosmological expansion.