PDA

View Full Version : Expansion of the Universe



johnwitts
2001-Dec-06, 11:16 PM
Ok, here goes nothing. If the universe was created in a big bang, and is therefore expanding, and when we look out into space we are looking back in time, how come everything far away is so far apart? Put it another way, say the Universe is 20 billion years old, and we can look back 10 billion years, if we look in opposite directions, things look 10 billion years 'away', in each direction. Yet these two parts of the sky are 20 billion years away from each other, when 20 billion years ago, they should have been in the same place. Am I making any sense? (Ignore the numbers, 20 billion years is probably wrong, but it helps with the maths!)

DStahl
2001-Dec-07, 05:14 AM
Geez. A couple of things spring to mind. First off, stars did not form until the Universe had been expanding for quite a long time--maybe .5 to 1 billion years, I think. Even then we couldn't hope to see single stars at the horizon of visibility, so probably the oldest luminous objects we can hope to see are galaxies which, according to current best thinking, formed some time after the first stars. The galaxies seen at the most remote distances do indeed seem to be smaller and less structured than the ones we see nearby. I don't remember, offhand, if they appear to be closer together. Maybe one of the many more knowledgable folks on the BABB can fill in the gaps left by my lazy mind.

The second note of interest is that the most tenable big bang theory includes a period of inflation very early on, when the nascent Universe expanded not by a paltry fraction of a percent per year but at an exponential rate, doubling and redoubling its size in fractions of a second. It's estimated by some that some 100 doubling of size before the special physical state called false vacuum decayed would be sufficient to create a Universe consistent with what we see. But there is no theoretical reason why the period of inflation couldn't have resulted in 200 or 400 doublings instead. If that's the case, the Universe could be vastly larger than the small part we can see...and even at the early stage when the first galaxies were flaring up it could have extended far beyond 10 billion lightyears.

I'll bet you get some other very informed responses on this question. I'm just an interested observer of science, so you must take my comments with a grain of salt. You might delve into <U>The Inflationary Universe</U>, by Alan Guth, and <U>Just Six Numbers</U> by Martin Rees, for layman-level overviews of cosmology.

--Don



<font size=-1>[ This Message was edited by: DStahl on 2001-12-07 00:21 ]</font>

GrapesOfWrath
2001-Dec-07, 06:43 AM
Welcome to the BABB! Just because things are twenty billion lightyears apart doesn't mean that we would see them as they were twenty billion years ago. As you say, we would see them as they were ten billion years ago.

<font size=-1>[Added welcome, sheesh, where are my manners]</font>

<font size=-1>[ This Message was edited by: GrapesOfWrath on 2001-12-07 01:45 ]</font>

johnwitts
2001-Dec-07, 01:16 PM
So, are we in the middle? My point about the 10 billion LY either way is that these things are 20 billion LY appart, and if we are looking back in time to 10 billion LY either way, these things got 20 billion LY away from each other in only 10 billion years. So, as the speed of light is always constant for the observer, and these points have moved apart 20 billion LY in only 10 billion years, then each point has moved away from the other at twice the speed of light. Either something else is going on here, of we shouldn't be able to see past hlfway to the start of the universe.

NottyImp
2001-Dec-07, 01:33 PM
Surely they are just movng in opposite directions, and hence the distance between them doubles?

Two objects moving away from each other at 1 m/s get 2 m further away from each other every second. Nothing changes if the speed happens to be close to the speed of light.

Tim Thompson
2001-Dec-07, 06:53 PM
I know that what I am about to say would drive our old friend JW nuts, but the analogy is not a bad one. Assume you are a bug on an expanding balloon. Now assume that you can only see along lines of sight that run in the surface of the balloon. The balloon has dots all over it, and you can see them as you look along the allowed balloon surface lines of sight. Two things become readily apparent if you let your brain stew on the analogy for a while: (1) Your view of the universe will be somewhat distorted, and (2) You will be unable to locate, or even to define the concept, of the "center" of the distribution of dots on the balloon surface. The reason for this latter observation is that the "center" can only be approached by looking in 3 dimensions, toward the space inside the balloon. But you can't look in any direction thaty does not lie along the surface of the balloon, you can't even directly sense the existence of that 3rd dimsnion.

But you can infer that the 3rd dimension exists by counting dots per unit surface area, making some assumptions about the dots being evenly (or predictably not evenly) spaced on the surface. That count as a function of "distance" from you will reveal that the surface is not a euclidean plane, but has curvature. You can do that with sounts of galaxies and distant galaxy clusters, and come to roughly the same conclusion. The "center" is somewhere else, in a direction that we can infer but not sense.

DStahl
2001-Dec-07, 07:09 PM
Tim, amigo, that has to be the best and clearest presentation of the balloon analogy I have ever read. My best compliments.

Notty Imp, the distant galaxies are not moving away from us through space (like a boat through water), the space between is expanding (as if water is welling up between the boats). The galaxies cannot move through space faster than c, but with enough space between us and them the space between can expand at a rate that makes the distance between us and them increase at a rate greater than c.

Ah, I have failed to achieve the TT level of clarity. Two boats can be dead in the water, but if water is welling up between them they may be forced apart anyway. Does that help?

For a real explanation, Google on "Charlie Lineweaver" and go from his personal page to the papers he has written (with Tamara Davis) on "superluminal" redshifts and on the "unchained galaxy" problem. When I get time I'll post links, but right now real life calls... /phpBB/images/smiles/icon_frown.gif

johnwitts
2001-Dec-07, 10:11 PM
Gotcha on the balloon analogy. But surely, if the balloon (of space) is expandidng, this applies to all space. Stars and galaxies move apart because the fabric of space is expanding, but then, so should the space within atoms expand also, making these bigger. Net result, no observable phenomonen. To go back to the balloon analogy, if we observe the dots moving away from each other, we would also observe the dots themselves getting bigger. And our bug, if he was 'enbedded' within the fabric of his universe (the rubber of the balloon), he too would expand at the same rate, and therefore wouldn't notice the expansion of the rest of the universe. All the tools he would use to measure the expansion would also be expanding along with the universe. I've never understood this notion that somehow the whole universe can expand without effecting the spaces between and within atoms, only the spaces between stars and galaxies.
Red shifts? Are these observed from stars within our own galaxy? Or just stars from other galaxies? If our own, does this mean our galaxy is expanding?

DStahl
2001-Dec-08, 01:39 AM
It seems logical that everything would expand, but it doesn't work that way. The expansion of space is very "weak" and is overcome even by the gravitational attraction between galaxies in clusters. The gravitational force binding stars into galaxies and planets into the Solar System is much stronger than that, and overcomes any expansion of space at local scales. And of course the electrostatic forces between molecules in matter is many times stronger even than the gravitational forces in the Solar System, so we and our yardsticks are not expanding.

As I understand it, we only see expansion between objects that are so far apart that they are not gravitationally attracted to each other by any appreciable amount. I guess that means for most purposes only the space seperating superclusters of galaxies is expanding.

<font size=-1>[ This Message was edited by: DStahl on 2001-12-07 20:45 ]</font>

johnwitts
2001-Dec-08, 02:06 AM
So, the red shift should not be observed from stars within our own galaxy? Is this what we actually see?

Donnie B.
2001-Dec-08, 03:23 AM
On 2001-12-07 21:06, johnwitts wrote:
So, the red shift should not be observed from stars within our own galaxy? Is this what we actually see?


The stars within our galaxy are far too close to us to show much effect of cosmological redshift, even if they weren't tightly bound by gravity as explained above.

We do see redshift in some stars within the Milky Way galaxy -- and blueshift in others. There are significant "proper motions" of stars besides their common rotation around the galactic center of mass. So we see them moving toward or away from us (or rather, that component of their proper motion that is directed toward or away from us). Of course, there are some that have little or no motion of that sort, and so we see them with little or no red- or blueshift.

In short, any cosmological redshift is overwhelmed by the effect of proper motion when you're looking at nearby objects.

thkaufm
2001-Dec-08, 03:59 AM
Using the balloon analogy, Is the universe thought to be finite in size, yet has no edge.
If you could travel for long enough, fast enough, would you return to your starting position from the opposite direction?

Tom K

johnwitts
2001-Dec-08, 10:14 PM
I thought that red shift was used to measure the distance to stars where the paralax shift due to the size of the Earths orbit was too small to measure, beyond a few hundred light years. Does that mean we can't measure the distances to stars within our own galaxy?

Donnie B.
2001-Dec-09, 02:23 AM
On 2001-12-08 17:14, johnwitts wrote:
I thought that red shift was used to measure the distance to stars where the paralax shift due to the size of the Earths orbit was too small to measure, beyond a few hundred light years. Does that mean we can't measure the distances to stars within our own galaxy?


Not using redshift. There are various ways to measure stellar distances within the Milky Way, parallax being the one used for the nearest stars. Another method can be used for certain special stars called Cepheid variables -- that technique can be used as a tape measure for nearby galaxies too.

Redshift is useful as a distance measure only for relatively distant galaxies.

johnwitts
2001-Dec-09, 09:37 PM
So, how do we know that red shift is caused by the galaxies receding, and not some other hither to unknown reason?

DStahl
2001-Dec-10, 08:12 AM
Excellent question. IMHO, we take our best guess at the cause of the redshift. Whatever the explanation, it has to satisfy the observations:

1. Galaxies that are farther away have higher redshift. (Problem: it's hard to judge how far away galaxies are, you have to find a standard candle like a supernova which is both bright enough to see at great distance and also has a consistent maximum luminosity. Quite difficult.)

2. The characteristic spectral signatures of the elements has to be preserved despite redshifting (or blueshifting). In other words, the emission lines characteristic of ionized hydrogen must be shifted down- or up-spectrum but not scrambled.

3. Redshifted or blueshifted light must not be scattered by whatever mechanism changes its frequency, or else we would not be able to resolve images at any great distance.

4. The explanation should account for redshifting and blueshifting by some plausible mechanism. I guess we would like to say "This would definitely cause light to be redshifted" rather than simply say "We dunno what could account for this."

There are probably some more conditions that I am forgetting. But the expanding Universe hypothesis meets these criteria, while some other possible explanations ("tired light," Compton scattering) don't. Again, IMHO as an amateur, there could be another explanation for the redshift phenomenon. It's just that the general consensus, and it's a pretty firm consensus, is that an expanding Universe is the best hypothesis for the facts as we know them.

--Don

Wally
2001-Dec-10, 01:06 PM
Another thing to keep in mind is that prior to the BB, space and time as we know it did not exist. You always hear about how all (known) matter was contained in an area the size of a pin head just before the BB, but this comparison is really kinda misleading, since space/time (again, as we know it) did not exist until after the BB. Not sure what point I'm trying to make here, or even how accurate it is, but I guess what I'm trying to say is when considering our current view of the universe, it may help to consider that everything really didn't start out at "point A" necessarily, since our perception of what "point A" is is limited to our 4 dimensional view of the universe, which didn't exist until AFTER the BB occurred. Help me out here guys. Am I on the right track???

Bob S.
2001-Dec-12, 03:33 PM
Let me see if I get the premise of the original question.

You have 3 points A, B, & C spaced at 10BLYs.

(A)-9-8-7-6-5-4-3-2-1-(B)-1-2-3-4-5-6-7-8-9-(C)

We are at B looking one direction and seeing A 10BLYs away and C at 10BLYs away in the oposite direction. So, would someone at C look across and see us at 10BLYs away and see A beyond us at 20BLYs away? Or because of the curvature of space see a different perspective? Would the view from C be something like this?

(B)-9-8-7-6-5-4-3-2-1-(C)-1-2-3-4-5-6-7-8-9-(A)

Or some variation such as A and B appearing to be at some acute angle with respect to C.
(B)
|
9
|
8
|
7
|
6
|
5
|
4
|
3
|
2
|
1
|
(C)-1-2-3-4-5-6-7-8-9-(A)

Okay, can we borrow somebody's warp-drive space ship so we can check this out?

ToSeek
2001-Dec-12, 05:02 PM
On 2001-12-12 10:33, Bob S. wrote:
Let me see if I get the premise of the original question.

You have 3 points A, B, & C spaced at 10BLYs.

(A)-9-8-7-6-5-4-3-2-1-(B)-1-2-3-4-5-6-7-8-9-(C)



I think the question is why don't we see "A" and "C" close together, since we're looking back to when the universe was close together - the farther back in time we look, the closer together things should be.

Roy Batty
2001-Dec-12, 05:39 PM
Okay, can we borrow somebody's warp-drive space ship so we can check this out?



I'm sorry, the Dilithium backend has gone on mine, its in the garage for repairs /phpBB/images/smiles/icon_smile.gif

John Kierein
2001-Dec-16, 12:00 PM
Look here for stuff on why the big bang is wrong.
http://www.angelfire.com/az/BIGBANGisWRONG/index.html
If folks think that light must blur sources if there is "scattering" then why can we see light going through water or glass? Surely the light interacts with such a transparent medium; it's significantly slowed! But there is not necessarily blurring. This is because the light wave is reconstructed via Huygens' secondary wavelets.

John Kierein
2001-Dec-16, 12:03 PM
I hate to argue with Tim, but even on a balloon, if it's expanding, the stars should look closer together as you look back in time.

David Simmons
2001-Dec-16, 12:10 PM
On 2001-12-16 07:00, John Kierein wrote:

This is because the light wave is reconstructed via Huygens' secondary wavelets.


Let's not confuse what happens in the actual physical mechanism with our model for explaining it.

John Kierein
2001-Dec-16, 12:33 PM
Are you trying to say the model's wrong? Because we don't see a big bang, we can still create a mosel for one? How many angels will fit on the head of a pin?

David Simmons
2001-Dec-16, 03:06 PM
On 2001-12-16 07:33, John Kierein wrote:
How many angels will fit on the head of a pin?


What is this supposed to mean? That something is trivial? If you want trivial try the Compton Effect to explain redshift.

I'm just saying that light waves are not reconstructed because of Huygens' construction. And you ought to know that.

DStahl
2001-Dec-20, 03:09 AM
John, I don't understand this:

"If folks think that light must blur sources if there is 'scattering' then why can we see light going through water or glass? Surely the light interacts with such a transparent medium; it's significantly slowed! But there is not necessarily blurring. This is because the light wave is reconstructed via Huygens' secondary wavelets."

I'm confused because it seems to me that transmission of light through a transparent substance is quite different from scattering off reflective surfaces, refractive scattering, and Compton scattering. Aren't all these photon-electron interactions quite well described by quantum physics, and tractable to mathematical analysis? My admittedly limited knowledge leads me to think that of the four--transmission, reflection, refraction, and Compton scattering--only transmission always results in photon propagation preserving both the wavelength and directionality of the incident photon. Am I incorrect?

--Don

DJ
2001-Dec-20, 04:40 PM
http://www.people.cornell.edu/pages/jag8/spacetxt.html


Check out the page with the Map, as it does a very good job in explaining the geometry one must be OK with to accept an expanding universe theory. I was able to understand this map, and no other explanation to date has layed it out in such laypeople terms.

I'm currently reading "The Nature of Space and Time" by Penrose and Hawking. One of the more interesting lectures is by Hawking where he talks about the inflationary models and some of their problems. Though this book is a few years old, I have not seen recent information which addresses his concerns.

We keep talking about surfaces, curvatures, etc. but the balloon uses the best analogy. Except, we keep talking about things on the surface of the balloon. But nothing is a surface unto itself, so what about the middle of the balloon? Are we living in 3 dimensions on top of time, which in this case would be the ever expanding surface of the balloon? If so, there ought to be some direction I can look in where I see the future... (If I was sitting on top of a balloon, for example, I would just look "up")

Philosophically, I have an easier time with this. Since things are not really "moving away from each other" on the grand scale, but instead everything in between is actually expanding like the example of upwelling between boats, then in essence, I am in the same place I always have been... only time has gone by.

So it's ok to still say that I'm in the center of the universe... it's just that the center of the universe is much larger than it used to be.

12 billion years? Doesn't seem like enough time for someone as complex as me to develop.

DJ

Kaptain K
2001-Dec-20, 05:00 PM
In the "balloon" analogy, objects (and observers) are not "on" the surface. They are "in" the surface. Two dimensional objects (and hypothetical beings) have length and width but no depth. In a two dimensional world, there is no "up". By analogy, we live "in" the three (or four) dimensional surface which is curved through higher dimensions. We cannot "look" in the direction of these higher dimensions.

_________________
TANSTAAFL!

<font size=-1>[ This Message was edited by: Kaptain K on 2001-12-20 12:01 ]</font>

DJ
2001-Dec-20, 05:24 PM
Funny how a lower can never see a higher.

Now THAT works on all levels.

SeanF
2001-Dec-20, 05:30 PM
On 2001-12-20 12:24, DJ wrote:
Funny how a lower can never see a higher.

Now THAT works on all levels.


Now, DJ, are you sure it works on levels higher than your own, levels which you can not see? /phpBB/images/smiles/icon_wink.gif

Bob S.
2001-Dec-26, 04:40 PM
I guess the adventures of Flatland's Mr. Square should be recommended reading at this point. Yes?

GrapesOfWrath
2001-Dec-26, 06:42 PM
On 2001-12-20 12:24, DJ wrote:
Funny how a lower can never see a higher.

Now THAT works on all levels.

Can you really see a lower?

We can imagine them, sure, but...what does it mean for us to "see" a two-dimensional object?

John Kierein
2001-Dec-27, 11:30 AM
On 2001-12-19 22:09, DStahl wrote:
John, I don't understand this:

"If folks think that light must blur sources if there is 'scattering' then why can we see light going through water or glass? Surely the light interacts with such a transparent medium; it's significantly slowed! But there is not necessarily blurring. This is because the light wave is reconstructed via Huygens' secondary wavelets."

I'm confused because it seems to me that transmission of light through a transparent substance is quite different from scattering off reflective surfaces, refractive scattering, and Compton scattering. Aren't all these photon-electron interactions quite well described by quantum physics, and tractable to mathematical analysis? My admittedly limited knowledge leads me to think that of the four--transmission, reflection, refraction, and Compton scattering--only transmission always results in photon propagation preserving both the wavelength and directionality of the incident photon. Am I incorrect?

--Don

The Compton effect is not necessarily an interaction with electrically charged particles, it applies to all massive particles regardless of charge. Nothing in the Compton effect involves charge; it is entirely explained in terms of conservation of energy and momentum. So unlike reflections from a surface, there is nothing to change the electric and magnetic vectors of the photon. So the ExH vector is unchanged and the wavefront is reconstructed without blurring.

DStahl
2001-Dec-28, 08:43 AM
John, I read your post and I think I understand where my difficulty lies. According to the physics text I have to hand (Fundamenals of Physics, Halliday and Resnick, 2<sup>nd</sup> Ed 1981), light transmitted through a substance can be understood as a phenomenon of electromagnetic waves:

"On this picture the incident wave of frequency v causes electrons in the scattering block [or the transparent substance] to oscillate at that same frequency. These oscillating electrons, like charges surging back and forth in a small radio transmitting antenna, radiate electromagnetic waves that again have this same frequency v."

However, Compton scattering, according to the text, "...cannot be understood if the incident x rays are regarded as an electromagnetic wave." The Compton effect can only be explained as a particle interaction, one in which the incident photon and an electron collide and rebound elastically.

According to the text, the change in wavelength of a photon due to Compton scattering is given by

Delta v = h/m<sub>0</sub>c(1 - cosine a)

where a is the scattering angle. Obviously, if the angle is 0 then the term (1 - cos a) goes to 0, delta v goes to 0, and there is no change in wavelength of the scattered photon. If, on the other hand, there is a change in wavelength, we may be assured that the redshifted photon will be emitted at angle a to the path of the incident photon.

In fact, my textbook says "Thus the Compton shift [delta v] depends only on the scattering angle [a] and not on the initial wavelength..." This seems to indicate pretty clearly that any photons which are redshifted by Compton scattering will unavoidably be deflected through an angle, and would seem to dictate that redshifted light from a star would act very much like the light from a streetlight in a dense fog: the photons would be deflected as they bounced from electron to electron, like light refracting from water droplet to water droplet, and the image of the star would be lost in a diffuse blur.

I don't want to seem confrontational; I enjoy your posts and respect your point of view. But I also think the above description of Compton scattering is accurate and well-established theoretically and experimentally.

--Don

2002-Jan-01, 04:09 AM
On 2001-12-19 22:09, DStahl wrote:
John, I don't understand this:

"If folks think that light must blur sources if there is 'scattering' then why can we see light going through water or glass? Surely the light interacts with such a transparent medium; it's significantly slowed! But there is not necessarily blurring.
[quote]
If you actually play with Huygens wavelets, and try to draw a scale diagram of what is happenng, you would understand. One wavelengths worth of light contains many atoms much smaller than that wavelength in a piece of glass. If the wavelength isn't big enough for you, the coherence length will include hundreds of atoms and molecules. If there is no inelastic scattering (change in frequency),Every atom within that volume is being driven in phase. That is why the Huygens wavelets combine to form a non distorted wavefront. The all inhomogeneities are smaller than the coherence length.

In an interstellar medium, the spacing between atoms is much larger than the coherence length of a star (and far far greater than the wavelength of the light). Therefore, in elastic scattering, the atoms in a coherence length are NOT scattering in phase. Compton scattering is inelastic. The wavelength changes, and is wavelength dependent.
[quote]
This is because the light wave is reconstructed via Huygens' secondary wavelets."
This is not a given. As I said, if you draw Huygens wavelets for scattering centers that are far apart and at random positions, like the interstellar medium, you would not get transmission without blurring.

Compton effect is a really well known type of scattering and it definetely would cause blurring.

I think that you are getting confused by Paul Marmet. Marmet is a physicist who claims that small angle scattering of light, together with Brehmstrahlung, can inelastically scatter even without changing the angle. I prefer to call this scattering that Marmet predicts as "Marmet scattering."

Marmet doesn't think that Maxwell's equations or special relativity is correct, and his theories are based on the supposed failures of these commonly accepted theories. Marmet uses Compton's name to convince people of his legitimacy since Marmet's theory is so controversial. He is one of thse guys who likes to call other scientists stupid. However, just because he isn't Mr. Personality doesn't mean that his theory is wrong. It just isn't Compton scattering.


He calls it Compton scattering even though it is his own theory. If it should turn out to be true, then he should get all the credit not Compton. Marmet uses Compton's name to give him legitimacy since his theory is so controversial.




I'm confused because it seems to me that transmission of light through a transparent substance is quite different from scattering off reflective surfaces, refractive scattering, and Compton scattering. Aren't all these photon-electron interactions quite well described by quantum physics, and tractable to mathematical analysis? Am I incorrect?

--Don


Yes you are incorrect. The process most of us called Compton scattering would cause blurring and spectral broadening. There is a theory by a physicist called Paul Marmet, pretty much known only through the Internet, that predicts another kind of scattering that could cause a red shift of the type measured in cosmology. However, mot scientists don't believe his theory. If he turns out correct, he should get all the credit. And all the blame if he is wrong.

DStahl
2002-Jan-01, 10:03 PM
Dr. Rosen:

Argh! Are you saying that Don's (DStahl's) assertion that Compton scattering is well understood and must cause blurring is incorrect, or are you agreeing with that statement and asserting Don is incorrect about something else? The last paragraph of your post has me confused all over again.

(Just when you thought it was safe to scatter photons again...*grin*)

--Don

John Kierein
2002-Jan-02, 02:02 PM
The shift per scattering is independent of wavelength, but the number of scatterings is proportional to the wavelength. See:
http://www.geocities.com/CapeCanaveral/9335/compton.html

DStahl
2002-Jan-03, 04:14 AM
Sure, John, but each scattering still propagates the redshifted photon at an angle to its original path. [added much later: I really don't intend to pursue this; it isn't and wasn't my intent to start an argument. I think I understand the proposal and the physics involved well enough now to let the matter lie.]

--Don

<font size=-1>[ This Message was edited by: DStahl on 2002-01-14 13:35 ]</font>

DoctorDon
2002-Jan-14, 05:43 PM
To try to answer the original poster's
question, you have to remember that what
we are seeing now is the light that was
emitted x number of years ago *at* the
distance x. In other words, while it is
convenient to think of expansion in terms
of a cone: (time goes downward)

abcde
a b c d e
a b c d e
a b c d e

However, what we (at, say, the letter "c") can see at the present (say, the bottom line) is anything on a cone expanding *up*ward from the bottom c.

Hence, the galaxies we see at 10 billion light years in either direction were 20
billion light years apart back then, but
they are *much* further apart "now", but
we can't see how far apart they are "now",
because the light they are emitting "now" is still 10 billion years away. When we look out 10 billion light years in any direction, we are seeing a sphere of light that was emitted at that time from that place, but is just getting to us now.

You say "Yet these two parts of the sky are 20 billion years away from each other, when 20 billion years ago, they should have been in the same place", but that latter clause
is an erroneous assumption. You say they
*are* 20 billion [light] years away from each
other, but you should be saying they *were*
20 billion light years away from each other
at the time the light was emitted.

Don Smith

Who, i'm afraid, is not keen on the new BB
interface. I miss the threading. How am I
supposed to indicate to *which* message in a
long thread I am replying?

DoctorDon
2002-Jan-14, 05:47 PM
So, of course, the new formatting here
messed up my illustration. Those "abcde"
letters had successively increasing numbers
of spaces between them.

And why, pray tell, am I a Bad *Newbie*????
I've been active here for *years*, and I've
got a PhD in the topic. I feel way too tired
to be a newbie. :-)

Grumble mumble,

Don

GrapesOfWrath
2002-Jan-14, 05:59 PM
On 2002-01-14 12:43, DoctorDon wrote:
How am I supposed to indicate to *which* message in a long thread I am replying?

Use the Reply-with-quote feature, but just make sure that you don't keep an excessive amount of the original post. (http://www.badastronomy.com/phpBB/viewtopic.php?topic=98&forum=5&1)

The Bad Astronomer
2002-Jan-14, 06:00 PM
And why, pray tell, am I a Bad *Newbie*????


Didn't you get the memo? People from MIT aren't allowed to get promoted. /phpBB/images/smiles/icon_wink.gif

Actually, the new board is a clean sweep; everything from the old board was wiped. That old software was a major pain, and this one, while still a bit bumpy, is much better. But you have to start all over again. I may remove ranking anyway; it promotes posting a lot just to move up.

DoctorDon
2002-Jan-14, 06:09 PM
Hi,

I don't see any "reply with quote feature",
just "new topic" and "reply".

No, Phil, I didn't get that memo :-), but it
doesn't surprise me. MIT is much akin to
a black hole; once you get inside its
event horizon, it is very difficult to ever
get out again. I am out at the moment
(University of Michigan), but I can feel
the ominous pull of its eldrich and cyclopean towers, even now...

Going back to reading some Lovecraft,

Don

DoctorDon
2002-Jan-14, 06:11 PM
On 2002-01-14 13:09, DoctorDon wrote:

I don't see any "reply with quote feature",
just "new topic" and "reply".



Found it. [sheepish grin]

Wait, so now that there's another Don S.
around here, what are we going to do????

Don

DStahl
2002-Jan-14, 06:41 PM
Good DoctorDon--if you wish you can use html code to insert extra spaces (non-breaking space): & n b s p ; with the spaces between the letters removed of course!

--Don (also)

Donnie B.
2002-Jan-14, 07:04 PM
On 2002-01-14 13:11, DoctorDon wrote:
Wait, so now that there's another Don S.
around here, what are we going to do????
Don


Er, not to mention... /phpBB/images/smiles/icon_biggrin.gif

<font size=-1>[ This Message was edited by: Donnie B. on 2002-01-14 14:05 ]</font>