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esoteric
2003-May-17, 07:40 PM
Hi.. I was in the shower today thinking (great place for it) and I starting wondering about the things mentioned in the subjet. A quote:

"Astronomers gauge an object’s distance from Earth by measuring its redshift—the amount by which the wavelength of its light is lengthened, or moved toward the red part of the spectrum, as the object moves away from Earth in the expanding universe. The higher the redshift, the more distant and younger the object. "

I don't fully understand how the redshift tells us an object is further away. A higher redshift should just indicate how FAST the object is travelling away from us (as in the dopler effect with sound). Why are objects that are farther away necessarily travelling away from us FASTER?

And I'm going to find this hard to explain in text, I may have to draw some diagrams.

Okay:

“We are seeing this redshift 5.80 quasar as it was only a billion years after the Big Bang, which is quite early in the history of the universe, since current estimates put the age of the universe at between 12 and 15 billion years."

Lets say for the sake of making it easy that the universe is 13 billion years old. By the standards given, that means that the light we are receiving from the quasar took 12 billion years to get to us (if it's 12 billion years old), but if it left when the universe was only a billion years old, the universe was a LOT smaller.. why didn't it reach us before our planet was even formed? Am I making sense? :D

Nagging questions..... :)

Thanks!

DrTypo
2003-May-17, 08:27 PM
Hello,
I'm not a scientist but I'll try to answer your questions...


I don't fully understand how the redshift tells us an object is further away. A higher redshift should just indicate how FAST the object is travelling away from us (as in the dopler effect with sound). Why are objects that are farther away necessarily travelling away from us FASTER?!

When astronomers use redshift to calculate the distance of galaxies, they don't consider the proper motion of galaxies. They use the fact that the universe is expanding.

Let's consider 3 galaxies A,B and C separated from each other by 1 billion ly .
A-B-C
So B is 1 billion ly away from A, and C 2 billions ly away from A.

After 1 billion year, the universe doubles its size:
A--B--C
Now B is 2 billions ly away from A and C 4 billions ly away from A.

Then again, 1 billion years passes. The universe is now 3 times its original size.
A---B---C
B is 3 billions ly away from A and C 6 billions ly away from A.

As you can see, if you're in the galaxy A, galaxy C seems to move away twice faster than galaxy B. ie: farther objects are faster.



Lets say for the sake of making it easy that the universe is 13 billion years old. By the standards given, that means that the light we are receiving from the quasar took 12 billion years to get to us (if it's 12 billion years old), but if it left when the universe was only a billion years old, the universe was a LOT smaller.. why didn't it reach us before our planet was even formed? Am I making sense? :D


The quasar was 12 billion ly away when when it sent its light (that is, 12 billion years ago). Now it is much farther away.
The universe was smaller back in those times but still very big. Maybe even infinite...

--
DrTypo

daver
2003-May-17, 08:46 PM
I can't do justice to this; i'll give a quick summary and suggest that you go follow some of the astronomy links that the BA likes to remind us are part of this website.

Astronomers have various means of measuring distance. The most direct is to measure the parallax of the star in question. Unfortunately, this only works for nearby stars. From these measurements, astronomers make a bit of a leap--they assume that particular types of stars have a given intrinsic brightness. So if you see one of these types of stars that appears to be one quarter as bright as another, you figure it is twice as far away (inverse square law). If you know the distance to the brighter star (say by being able to measure its parallax) you can infer the distance to the dimmer star.

Astronomers have put together a variety of these measurements in order to roughly determine the distances to various stars and to some nearby galaxies. When they started measuring distances to various galaxies (by comparing the brightness of supernova in the galaxies for closer ones, and by guessing that similar galaxies should have similar luminosities and applying the inverse square law again to determine distances for dimmer galaxies) they noticed something a bit funny. The more distant the galaxy, the greater the red shift of the galaxy--the faster the galaxy seemed to be moving away from us.

This seemed consistent enough that they generalized it and concocted a constant--Hubble's constant--to tie the distance of an object to its velocity away from us, or to its redshift. There has been quite a bit of variability in this constant as data are analyzed and reanalyzed and complicating factors such as interstellar dust compensated for, but things seem to hold together--distant objects seem to be retreating from us, and the more distant the object, the faster it seems to be retreating.

As i said, you should try following some of the links; here's one: http://www.badastronomy.com/bitesize/hubble_expand.html

Oh, a final note. There's nothing special about our location in space (it's not like our galaxy needs mouthwash or a deodorant)--outside of local groups, every galaxy is receeding from every other galaxy. The universe is expanding (recent indications are that the rate of expansion is actually increasing).

Grey
2003-May-17, 09:28 PM
Lets say for the sake of making it easy that the universe is 13 billion years old. By the standards given, that means that the light we are receiving from the quasar took 12 billion years to get to us (if it's 12 billion years old), but if it left when the universe was only a billion years old, the universe was a LOT smaller.. why didn't it reach us before our planet was even formed? Am I making sense? :D
Daver does a good job of answering your first question. For this, since the universe is expanding as the light travels, it doesn't cover ground as quickly as you.d expect. Imagine you were walking along a rubber band that's being stretched as you walk. Even if you were walking fast enough to cover the distance fairly quickly, it would take you longer than expected since your destination doesn't remain fixed.

esoteric
2003-May-17, 09:43 PM
Whew... I always get chills thinking about this kind of stuff. Must be the closest thing to a religious experience that I ever have..

@DrTypo

Fascinating! I recall reading about this somewhere else. It does make perfect sense in the way that you have explained it, thanks.

I'm still having trouble wrapping my head around the quasar bit, though. Well, rather, I'm having a hard time solidifying the concepts of expanding space and time.

If the light from the quasar was sent out so long ago, and everything is moving so fast, then if the quasar still exists, it must be in a vastly different position that we see it in. Indeed, the data we have that shows the structure and positions of the galaxies in our universe is entirely out-dated. The concept that our visualization of the structure of the universe is more and more wrong the further and further out we look is just... fascinating. I wonder if it would be possible to extrapolate what the structure of the universe actually presently is, based on the vectors that the galaxies we measure hold and their distance from us as measured in time. The mind boggles... :D

Did some more searching.. there seems to be a wide variety of contradicting points on this issue. (The question of the quasars light and distance). Guess I'll have to settle for.. "not quite sure yet"... :)

@daver

I read that link you provided. So many other questions pop into ones head. This is was fascinates me about science, there are no end to the questions provided by each answer we discover.

So the universe, the fabric of space-time, is expanding. If the fabric of space-time is expanding, then why doesn't everything expand uniformly (and therefore not look like it's expanding)? Are we humans affected by this at all, or do the atomic and moleculor forces bind us up so tightly that the distances between atoms (and electrons and their nuclei) not expand as well? And the gravitation forces between the planets and stars not cause them to expand also with the universes expansion?

Eeep. :o

Sorry, you guys can probably take most of these questions as rhetorical. :D

nebularain
2003-May-17, 10:11 PM
Hello,
I'm not a scientist . . .

. . . but I did stay in a Holliday Express Inn last night!

esoteric
2003-May-17, 10:26 PM
:lol:

Oh man... I can't believe that I remember that commercial and actually get your joke..... :D

Thomas
2003-May-18, 10:29 AM
I don't fully understand how the redshift tells us an object is further away. A higher redshift should just indicate how FAST the object is travelling away from us (as in the dopler effect with sound). Why are objects that are farther away necessarily travelling away from us FASTER?
Big Bang Cosmologists conclude that more distant objects move faster because they ASSUME the redshift to be caused by the Doppler effect as more distant galaxies show a higher redshift. No one has actually observed yet that the distance between galaxies increases with time (obviously you could tell this only after billions of years). In fact, you should not think that the Hubble 'law' is an exact relationship; it is only an average tendency with quite a significant spread. It is even known that there are spectral lines from the same object (!) that show differences in the redshift by up to 10%. This does of course completely invalidate the interpretation of the redshift as a Doppler effect. I have consequently suggested an alternative explanation for the galactic redshift as being due to the electric microfields in the intergalactic plasma (i.e. the redshift would essentially be distance related not velocity related) (see my website http://www.plasmafacts.de (Cosmological Redshifts) (http://www.plasmafacts.de/) for more details). There are of course also problems of a general conceptual nature if you assume the universe is expanding (see my website http://www.physicsmyths.org.uk/cosmology.htm).



Lets say for the sake of making it easy that the universe is 13 billion years old. By the standards given, that means that the light we are receiving from the quasar took 12 billion years to get to us (if it's 12 billion years old), but if it left when the universe was only a billion years old, the universe was a LOT smaller.. why didn't it reach us before our planet was even formed? Am I making sense? :D
Daver does a good job of answering your first question. For this, since the universe is expanding as the light travels, it doesn't cover ground as quickly as you.d expect. Imagine you were walking along a rubber band that's being stretched as you walk. Even if you were walking fast enough to cover the distance fairly quickly, it would take you longer than expected since your destination doesn't remain fixed.
Your explanation is inconsistent with the constancy of the speed of light, according to which the time of the light signal to reach the observer should be independent of whether the latter is moving relative to the source or not. Esoteric's argument is therefore a valid one and illustrates indeed one of the many flaws in the Big-Bang theory.

dgruss23
2003-May-18, 02:23 PM
It is even known that there are spectral lines from the same object (!) that show differences in the redshift by up to 10%. This does of course completely invalidate the interpretation of the redshift as a Doppler effect.

In working on your plasma model have you been able to develop a way to explain this?

esoteric
2003-May-18, 05:32 PM
This does of course completely invalidate the interpretation of the redshift as a Doppler effect.

In some quick searching for answers, there does appear to be some controversy surrounding the Hubble constant.


(see my website http://www.plasmafacts.de (Cosmological Redshifts) (http://www.plasmafacts.de/)). (see my website http://www.physicsmyths.org.uk/cosmology.htm).

Oh no! More reading! More theories! :D But seriously, I haven't read the webpages yet, but I think it's always good to hear alternative ideas.

Thanks!

Thomas
2003-May-18, 05:47 PM
It is even known that there are spectral lines from the same object (!) that show differences in the redshift by up to 10%. This does of course completely invalidate the interpretation of the redshift as a Doppler effect.
In working on your plasma model have you been able to develop a way to explain this?
It can't be a wavelength dependence because the discrepancy exists only for some lines. It may be due to the different damping width of the lines i.e. the coherence length of the corresponding wavetrains: the wavetrains of normal dipole transitions (for visible wavelengths) are about 1 m long (which is probably about the same or less than the distance between two charges in intergalactic space), whereas the length of wavetrains arising from metastable transitions are orders of magnitudes longer. I have not tried to develop this theoretically any further yet. It is anyway likely to be a completely new physical effect which can not be derived from present principles of optics/plasma physics. At least it is a theoretical possibility, unlike the Doppler effect.

kurtisw
2003-May-18, 05:49 PM
In fact, you should not think that the Hubble 'law' is an exact relationship; it is only an average tendency with quite a significant spread.

While there is some spread in the relation between the distance of a
galaxy and the speed at which it is receeding from us in the nearby
universe (this is mainly due to gravity from nearby galaxies pulling on
one another), at larger distances the relation is very tight.
Here is a graph (http://cfa-www.harvard.edu/cfa/oir/Research/supernova/highz/figures/hz_highzhub_col_bothbig.gif) showing this. The graph is a bit complex, but I can
explain. Focus only on the top half of the graph. The graph plots the
brightness of a certain type of supernova on the vertical axis and the
speed at which the supernova is moving away from us on the horzontal
axis. As the supernova is further away, it gets fainter, with fainter
supernovae at the top of the graph and brighter ones at the bottom. The
lines drawn on the graph show the relation you would expect if the
distance and velocity are related as predicted by Big Bang cosmology,
with the differing lines just indicating different possible versions of
the theory. But most importantly, you see that the relation is very tight.
Some astronomers argue about possible problems using the supernova
to find distance, but these arguments are mainly in trying to discern
between the three drawn lines.





Daver does a good job of answering your first question. For this, since the universe is expanding as the light travels, it doesn't cover ground as quickly as you.d expect. Imagine you were walking along a rubber band that's being stretched as you walk. Even if you were walking fast enough to cover the distance fairly quickly, it would take you longer than expected since your destination doesn't remain fixed.
Your explanation is inconsistent with the constancy of the speed of light, according to which the time of the light signal to reach the observer should be independent of whether the latter is moving relative to the source or not. Esoteric's argument is therefore a valid one and illustrates indeed one of the many flaws in the Big-Bang theory.

No, the argument is not inconsistent. Relativity states that all
observers measure the same speed of light, regardless of their motion
relative to one another. In relativity, time itself is not an absolute, and
neither is distance. The speed of light is the absolute.

The first explanation is correct; the light takes a longer time to reach us
than you would expect because the Universe is expanding; i.e. more
space is appearing in front of the light, and it takes time for the light to
cross that additional space, in which time more space has appeared
between the light and us, and so on.

It's like trying to run up the "down" escalator. It takes longer than using
normal stairs because more steps keep appearing in front of you, and the
motion of the steps is taking you further away from the goal. Eventually
you can make it (if you are moving fast enough), but is has taken a
longer period of time than if the stairs were still.

Thomas
2003-May-18, 06:17 PM
In fact, you should not think that the Hubble 'law' is an exact relationship; it is only an average tendency with quite a significant spread.

While there is some spread in the relation between the distance of a
galaxy and the speed at which it is receeding from us in the nearby
universe (this is mainly due to gravity from nearby galaxies pulling on
one another), at larger distances the relation is very tight.
Here is a graph (http://cfa-www.harvard.edu/cfa/oir/Research/supernova/highz/figures/hz_highzhub_col_bothbig.gif) showing this
But the relationship in this graph is not very tight at all, especially not for high z. In fact, a number of the data points miss the curve by 2-3 times their error bar.






Daver does a good job of answering your first question. For this, since the universe is expanding as the light travels, it doesn't cover ground as quickly as you.d expect. Imagine you were walking along a rubber band that's being stretched as you walk. Even if you were walking fast enough to cover the distance fairly quickly, it would take you longer than expected since your destination doesn't remain fixed.
Your explanation is inconsistent with the constancy of the speed of light, according to which the time of the light signal to reach the observer should be independent of whether the latter is moving relative to the source or not. Esoteric's argument is therefore a valid one and illustrates indeed one of the many flaws in the Big-Bang theory.

No, the argument is not inconsistent. Relativity states that all
observers measure the same speed of light, regardless of their motion
relative to one another. In relativity, time itself is not an absolute, and
neither is distance. The speed of light is the absolute.

The first explanation is correct; the light takes a longer time to reach us
than you would expect because the Universe is expanding; i.e. more
space is appearing in front of the light, and it takes time for the light to
cross that additional space, in which time more space has appeared
between the light and us, and so on.

It's like trying to run up the "down" escalator. It takes longer than using
normal stairs because more steps keep appearing in front of you, and the
motion of the steps is taking you further away from the goal. Eventually
you can make it (if you are moving fast enough), but is has taken a
longer period of time than if the stairs were still.
But you can't add the speed of light to your speed like you add the speed of the escalator to your speed. This is the whole point about the constancy of the speed of light (if you are interested, I have addressed this point on my webpage http://www.physicsmyths.org.uk/lightspeed.htm).

David Hall
2003-May-18, 06:34 PM
So the universe, the fabric of space-time, is expanding. If the fabric of space-time is expanding, then why doesn't everything expand uniformly (and therefore not look like it's expanding)? Are we humans affected by this at all, or do the atomic and moleculor forces bind us up so tightly that the distances between atoms (and electrons and their nuclei) not expand as well? And the gravitation forces between the planets and stars not cause them to expand also with the universes expansion?

It looks like you've pretty much answered your own question. Yes, on a local level, the expansion is so small that the other forces completely overwhelm it. People, planets, and even galaxies all are able to hold together against the expansion of space around them. The effect doesn't start to play a big role until you reach beyond the size of a galactic cluster. At the megaparsec level gravity and the other forces start to become too weak to hold matter back against the expansion, so we have "islands" of matter growing ever more distant from each other.

Recently there's been a new twist added to the mix. Not only is space expanding, but measurements have shown that the rate of that expansion is increasing. That is, there is something actively pushing the expansion ever faster. The best explanation for this is that there might actually be a new force at work, a "dark energy" that acts as a repulsive force at great distances. The jury is still out on that one, but something sure seems to be going on. I suggest Googling on dark energy if you want to learn more. There have also been past discusions about it here.

esoteric
2003-May-18, 08:51 PM
Recently there's been a new twist added to the mix. Not only is space expanding, but measurements have shown that the rate of that expansion is increasing. That is, there is something actively pushing the expansion ever faster. The best explanation for this is that there might actually be a new force at work, a "dark energy" that acts as a repulsive force at great distances. The jury is still out on that one, but something sure seems to be going on.

Yes, I've read a little about this. It's an interesting idea that raises still other questions about the origin of this universe, what came before it (if anything) and where the universe is headed...

Thanks!

RickNZ
2003-May-18, 10:09 PM
Noo thomas again.
Id politely suggest esoteric to ignore him because quite simply his 'suggestion' has already been debunked by others like princeton yet here he is back again making the same claims like nothing happened!

TrAI
2003-May-19, 01:58 AM
But you can't add the speed of light to your speed like you add the speed of the escalator to your speed. This is the whole point about the constancy of the speed of light (if you are interested, I have addressed this point on my webpage http://www.physicsmyths.org.uk/lightspeed.htm).

As far as my understanding of this goes, I look at the universe as the medium that light moves through, not like 'ether', but that the lights possision is bound by the universe, and its speed is a property of the universe. If the uneverse itself moves or expand, light must move with it. This means that though the local speed of light remains the same, there can be added more space between the light and the observer, making it seem like the light comes to the observer later than expected. I think the universe itself may even expand faster than lightspeed.

But as I am not educated in this field I can not really garantee this explanations accuracy, but someone else might be able to correct me if they are to wrong :-)

Thomas
2003-May-19, 09:08 AM
This does of course completely invalidate the interpretation of the redshift as a Doppler effect.
In some quick searching for answers, there does appear to be some controversy surrounding the Hubble constant.
The uncertainty regards the value of the Hubble constant does not invalidate the Doppler effect as an explanation. It is merely due to systematic errors when determining the distances of the objects. The data points could still fall excactly on a straight line, but the slope of this line would be uncertain (and it is this which determines the Hubble constant).

However, if data points show significant random deviations from a straight line, this indicates that the redshift does in fact not strictly depend on the distance but is only closely related to it. This should rule out the Doppler effect as an explanation. Instead it supports the assumption that the redshift is related to the column density of plasma between source and observer. This should be roughly proportional to the distance but allows for deviations due to statistical changes of the plasma density in different regions of space.

However, the more crucial argument is that the redshift is not even identical for all spectral lines from the same object. If interpreted as a Doppler shift, one would have to demand excatly the same redshift for all lines in all parts of the spectrum.

John Kierein
2003-May-19, 10:40 AM
It is even known that there are spectral lines from the same object (!) that show differences in the redshift by up to 10%. This does of course completely invalidate the interpretation of the redshift as a Doppler effect.

In working on your plasma model have you been able to develop a way to explain this?
Mine does.
http://www.angelfire.com/az/BIGBANGisWRONG/index.html

Grey
2003-May-19, 01:46 PM
However, if data points show significant random deviations from a straight line, this indicates that the redshift does in fact not strictly depend on the distance but is only closely related to it. This should rule out the Doppler effect as an explanation.
Don't be silly. The redshift on an object can be directly measured, of course, but when you want to then calculate the distance independently, you run into all kinds of difficulty. You have to establish standard candles, there are always assumptions that you know are only approximations, and if you're doing this kind of calculation, you just accept that and do the best you can. One of the projects that I'm working on will involve a survey of thousands of distant type Ia supernovae (which have a very characteristic light curve, so their intrinsic brightness can be calculated quite accurately) to use as standard candles to try to get better data, particularly on the issue of the accelerating expansion. Unfortunately, it's not due for launch until 2010.

There's going to be error in the measurement, so the data points are going to spread, and that's just par for the course. Don't talk about how some of the points are further away than their error bars; the error bars aren't some kind of magical indication of the maximum error, they're generally placed one standard deviation out, so it's perfectly possible (in fact, completely expected) to have points further away just from statistical error. And that doesn't even take into consideration that you might have some kind of systematic error if your distance measurements are not correct. The data really support the redshift-distance relationship nicely.


However, the more crucial argument is that the redshift is not even identical for all spectral lines from the same object. If interpreted as a Doppler shift, one would have to demand excatly the same redshift for all lines in all parts of the spectrum.
I don't know a single instance of this. I do know of cases where the reshift can be different for different parts of an object (edge-on spiral galaxy; the arms on one side are rotating toward us, so the redshift is a little lower than expected while the arms on the other side have a slightly higher redshift). Can you point me to references for a couple examples?

Spaceman Spiff
2003-May-19, 02:27 PM
However, if data points show significant random deviations from a straight line, this indicates that the redshift does in fact not strictly depend on the distance but is only closely related to it. This should rule out the Doppler effect as an explanation.
Don't be silly. The redshift on an object can be directly measured, of course, but when you want to then calculate the distance independently, you run into all kinds of difficulty. You have to establish standard candles, there are always assumptions that you know are only approximations, and if you're doing this kind of calculation, you just accept that and do the best you can. One of the projects that I'm working on will involve a survey of thousands of distant type Ia supernovae (which have a very characteristic light curve, so their intrinsic brightness can be calculated quite accurately) to use as standard candles to try to get better data, particularly on the issue of the accelerating expansion. Unfortunately, it's not due for launch until 2010.

There's going to be error in the measurement, so the data points are going to spread, and that's just par for the course. Don't talk about how some of the points are further away than their error bars; the error bars aren't some kind of magical indication of the maximum error, they're generally placed one standard deviation out, so it's perfectly possible (in fact, completely expected) to have points further away just from statistical error. And that doesn't even take into consideration that you might have some kind of systematic error if your distance measurements are not correct. The data really support the redshift-distance relationship nicely.


However, the more crucial argument is that the redshift is not even identical for all spectral lines from the same object. If interpreted as a Doppler shift, one would have to demand excatly the same redshift for all lines in all parts of the spectrum.
I don't know a single instance of this. I do know of cases where the reshift can be different for different parts of an object (edge-on spiral galaxy; the arms on one side are rotating toward us, so the redshift is a little lower than expected while the arms on the other side have a slightly higher redshift). Can you point me to references for a couple examples?


I have to ditto Grey on these points raised by Thomas. In regards to Grey's last question, I'd specifically like to know of an example of this case:


It is even known that there are spectral lines from the same object (!) that show differences in the redshift by up to 10%. This does of course completely invalidate the interpretation of the redshift as a Doppler effect.

John Kierein
2003-May-19, 03:59 PM
Quasars have multiple red shifts. Many of the various elements have different red shifts and sometimes the emission lines have different red shifts than the absorption lines. Sometimes this is attempted to be explained by saying that the lines are not intrinsic to the quasar, but are from intervening material that has a different red shift.

Grey
2003-May-19, 04:46 PM
Quasars have multiple red shifts. Many of the various elements have different red shifts and sometimes the emission lines have different red shifts than the absorption lines. Sometimes this is attempted to be explained by saying that the lines are not intrinsic to the quasar, but are from intervening material that has a different red shift.
Ah, he was referring to the difference between the emission and absorbtion spectra of distant objects. Is there any particular reason that absorbtion caused by intervening material with a lower redshift is not a valid explanation? As for differences in the emission spectra, I'd mentioned that I know of objects where one portion can have a different redshift based on proper motion. As with the galaxies where one part is clearly moving toward us and the other away due to rotation, many quasars show jets of ejected material at high velocity, which can easily account for a difference in proper motion. Do you know of any example of an object which doesn't have such a simple explanation that therefore necessitates a more radical hypothesis?

Thomas
2003-May-19, 04:48 PM
However, if data points show significant random deviations from a straight line, this indicates that the redshift does in fact not strictly depend on the distance but is only closely related to it. This should rule out the Doppler effect as an explanation.
Don't be silly. The redshift on an object can be directly measured, of course, but when you want to then calculate the distance independently, you run into all kinds of difficulty
..........
There's going to be error in the measurement, so the data points are going to spread, and that's just par for the course. Don't talk about how some of the points are further away than their error bars; the error bars aren't some kind of magical indication of the maximum error, they're generally placed one standard deviation out, so it's perfectly possible (in fact, completely expected) to have points further away just from statistical error
Error bars of one standard deviation ?. Serious science uses 2 (or more) standard deviations for error bars and with this only 5% (or fewer) of the error bars should fall outside the curve. I don't know what kind of error bars they used in the reference given by Kurtisw (http://cfa-www.harvard.edu/cfa/oir/Research/supernova/highz/figures/hz_highzhub_col_bothbig.gif), but fact is that about 20 out of 70-80 error bars do not match the curve. I would not describe this as convincing evidence. Why did they not use better statistics? Did they fear that the data would go off the rail altogether?
While the data would probably not rule out the Doppler effect if these are indeed error bars of one standard deviation, they certainly would not provide conclusive evidence in favour of it. The data are statistically simply not good enough and should not be used.
If you can't explain some of the behaviour in the data, then I am afraid you have to modify your theory in order to take this into account. Otherwise you might as well resort to guesswork.



However, the more crucial argument is that the redshift is not even identical for all spectral lines from the same object. If interpreted as a Doppler shift, one would have to demand excatly the same redshift for all lines in all parts of the spectrum.
I don't know a single instance of this. I do know of cases where the reshift can be different for different parts of an object (edge-on spiral galaxy; the arms on one side are rotating toward us, so the redshift is a little lower than expected while the arms on the other side have a slightly higher redshift). Can you point me to references for a couple examples?
I shall try to dig out the reference but it may take me a couple of days (I have to go to the University Library for this).

Grey
2003-May-19, 05:32 PM
Error bars of one standard deviation ? This is what I would use if I want to hide the fact that the data points do not match my theory. Serious science uses 2 (or more) standard deviations for error bars and with this only 5% (or fewer) of the error bars should fall outside the curve. I don't know what kind of error bars they used in the reference given by Kurtisw (http://cfa-www.harvard.edu/cfa/oir/Research/supernova/highz/figures/hz_highzhub_col_bothbig.gif), but fact is that about 20 out of 70-80 error bars do not match the curve. I would not describe this as convincing evidence. Why did they not use better statistics? Did they fear that the data would go off the rail altogether?
You're joking, right? Go consult a basic text on error analysis (Bevington and Robinson is generally considered a classic). I also don't know for certain what they used for error bars in that particular study, but in "serious science" it's assumed to be a single standard deviation unless stated otherwise. That means that about 37% of the data points should be further away than their error bar. In a group of 70 to 80, about 25 to 30 should miss. If anything, the data shown above is a surprisingly good fit.

I'm not certain what you mean by using "better" statistics. They analyzed the data that was available to them and used proper statistical methods to estimate the error involved. They don't get to choose what their data are, unless you're suggesting that they've deliberately falsified their data, which I don't think that you're doing. There are certainly disagreements about the details at the high-z end (the lower half of the graph highlights these), which is why work is on to conduct larger surveys, but the general correlation seems dead on.


I shall try to dig out the reference but it may take me a couple of days (I have to go to the University Library for this).
I look forward to seeing them! Thank you.

Thomas
2003-May-20, 05:18 PM
I also don't know for certain what they used for error bars in that particular study, but in "serious science" it's assumed to be a single standard deviation unless stated otherwise. That means that about 37% of the data points should be further away than their error bar. In a group of 70 to 80, about 25 to 30 should miss. If anything, the data shown above is a surprisingly good fit.

It does not really matter how many standard deviations the error bar indicates as long as you know how many it is. For the Hubble diagram discussed above, I found in the meanwhile a reference which gives the distance error as 8% (http://www.noao.edu/noao/noaonews/jun98/node2.html). This would correspond to an error in the distance modulus of about 0.2 for m-M=40 (d=10^9 parsec) (after the formula m-M=5log(d)-5 ) and corresponds to the error bars (see lower part of the diagram). So in this case it seems that the error bars indicate indeed 1 standard deviation. The question is of what scientific value this information is, as it still leaves the possibility that a comparable random scatter of the data points is in the actual signal rather than caused by the uncertainties in the measurement. Looking at the lower part of the diagram, the data points spread over a range m-M=0.8 for z<0.1, but only m-M=0.4 for higher z, yet in the latter range the slightly higher values are deemed significant, whereas the stronger variations in the former range have been deemed insignificant and dumped into the average. Smaller error bars (i.e. better measurements) might therefore well reveal fluctuations in the redshift that invalidate a strict relationship to the distance (i.e. the Doppler effect).


P.S.: I found the references regards the redshift differences in galactic emission lines and shall post them tomorrow here (I want to scan in some photocopies first and put these on my website for reference).

Spaceman Spiff
2003-May-20, 05:23 PM
Quasars have multiple red shifts. Many of the various elements have different red shifts and sometimes the emission lines have different red shifts than the absorption lines. Sometimes this is attempted to be explained by saying that the lines are not intrinsic to the quasar, but are from intervening material that has a different red shift.
Ah, he was referring to the difference between the emission and absorbtion spectra of distant objects. Is there any particular reason that absorbtion caused by intervening material with a lower redshift is not a valid explanation? As for differences in the emission spectra, I'd mentioned that I know of objects where one portion can have a different redshift based on proper motion. As with the galaxies where one part is clearly moving toward us and the other away due to rotation, many quasars show jets of ejected material at high velocity, which can easily account for a difference in proper motion. Do you know of any example of an object which doesn't have such a simple explanation that therefore necessitates a more radical hypothesis?

If you are speaking of intervening (aka intergalactic) absorption, such as the so-called "Lyman alpha forest", then this is gas strewn through the universe along the line of sight to the quasar (passing through galaxy cluster environments, etc). However, some quasars have absorption in their spectra that is INTRINSIC. It's usually very broad absorption, i.e. broader than even its emission lines, spanning wavelengths to shorter wavelengths than the corresponding emission line of that specie (like stellar P-Cygni spectra, only much more spectacular). This absorption is known to be associated with an outflow from the central environs of the quasar. We observe the absorption blueward (shorter wavelengths) of the corresponding emission line -- so gas is moving outward and that gas along the line of sight will cause absorption that is blueshifted relative to the quasar restframe. Nothing at all mysterious.

kurtisw
2003-May-20, 06:50 PM
Looking at the lower part of the diagram, the data points spread over a range m-M=0.8 for z<0.1, but only m-M=0.4 for higher z, yet in the latter range the slightly higher values are deemed significant, whereas the stronger variations in the former range have been deemed insignificant and dumped into the average.

To me, the error bars look fairly consistent over redshift. Some individual
points at high z have smaller error bars than individual points at lower z, but
the error bars depend on several factors, including how well the supernova's
light curve was observed. Since the high-z supernovae are the "interesting"
ones, it is not surprising that these were observed more often.

The variations at the lowest z cluster around the the expected mean and
suffer from a distinct lack of sampling. This is because one must survey a
much larger area of sky to find supernovae in the nearby universe. So the
supernova efforts are focusing on locating nearby supernovae. Those
data are still coming in. But for now, I think that the data are too sparse
to say that there are significant deviations at low redshift.

There are several fairly robust statistical estimators; if you want to make
a statement about any significance of deviations of the points then you need
to use one of those to calculate the probability that the observed and
predicted samples don't agree. It is these statistics that permit the authors
to draw fairly convincing conclusions from the high-z data.



Smaller error bars (i.e. better measurements) might therefore well reveal fluctuations in the redshift that invalidate a strict relationship to the distance (i.e. the Doppler effect).

Perhaps, but it is hard to reduce the error bars. These are not easy
observations! I think the best current approach is to build up a larger
sample. Larger samples will permit precise determination of the
distance modulus-redshift relation even if the scatter from individual data
points is still large.

Further, this plot is only one example of standard candles in astrophysics.
There are many more. And they all lead to the same conclusion -- that
distance and redshift are related in the way that one would expect
from cosmological redshifts.

And last, I'd like to quibble about terminology. Cosmological redshifts
are not technically Doppler shifts caused by the motion of objects away
from us. The redshift is due to the stretching of the wavelengths of light
due to the expansion of the space that the light is travelling through. The
difference is not particularly important for this particular discussion, but
if we are going to argue over statistics, I think we should all be on the same
page with regard to the underlying physics.

Grey
2003-May-20, 07:47 PM
So in this case it seems that the error bars indicate indeed 1 standard deviation. The question is of what scientific value this information is, as it still leaves the possibility that a comparable random scatter of the data points is in the actual signal rather than caused by the uncertainties in the measurement.
The theoretical model matches the data available to the limit of the error in the measurements. That's always the best that you can do. There's always a possiblity that there is something more interesting going on, but without the data to show it, it's just speculation.


Smaller error bars (i.e. better measurements) might therefore well reveal fluctuations in the redshift that invalidate a strict relationship to the distance (i.e. the Doppler effect).
It's certainly true that better measurements may reveal that there are differences from the theoretical model which are currently hidden in the error. That's why there are efforts to gather more data points, and try to improve the precision. Unfortunately, gathering accurate data on the distance of objects which are very far away is not easy, and it will probably be a few years before we can expect a significant change in the precision here. Sadly, one cannot just decide to improve the precision of measurements.

Once such data are available, if there is a discrepancy, then there would need to be a refinement of the model. The Doppler-based redshift model fits the data very well, though, so it seems far more likely that this would involve some small variation that needs to be added to the existing model, rather than completely throwing it out. And of course, it's entirely possible that improved data will simply support the existing model. Suggesting that improved data may provide support for a radical new model, and that we should therefore discount the current one, seems a bit premature.


P.S.: I found the references regards the redshift differences in galactic emission lines and shall post them tomorrow here (I want to scan in some photocopies first and put these on my website for reference).
I do look forward to seeing the information. Unusual objects are always fascinating!

Grey
2003-May-20, 07:52 PM
And last, I'd like to quibble about terminology. Cosmological redshifts are not technically Doppler shifts caused by the motion of objects away from us. The redshift is due to the stretching of the wavelengths of light due to the expansion of the space that the light is travelling through. The difference is not particularly important for this particular discussion, but if we are going to argue over statistics, I think we should all be on the same page with regard to the underlying physics.
You're quite correct here, and now I feel silly for not having quibbled about it myself! :)

Thomas
2003-May-21, 08:58 PM
And last, I'd like to quibble about terminology. Cosmological redshifts are not technically Doppler shifts caused by the motion of objects away from us.
The redshift is due to the stretching of the wavelengths of light
due to the expansion of the space that the light is travelling through. The
difference is not particularly important for this particular discussion, but
if we are going to argue over statistics, I think we should all be on the same page with regard to the underlying physics.
I don't get your point. Are you saying that galaxies are not receding at all? If they are receding (which I take it you assume), then there should certainly be a redshift; however the reverse is not necessarily true.

Thomas
2003-May-21, 09:12 PM
P.S.: I found the references regards the redshift differences in galactic emission lines and shall post them tomorrow here (I want to scan in some photocopies first and put these on my website for reference).
I do look forward to seeing the information. Unusual objects are always fascinating!
OK, here are the references:

First of all, considering the speculative nature of the assumption of a galactic recession, I find it astonishing that apparently no attempt has been made so far to verify the Hubble Law for its validity throughout the electromagnetic spectrum. I had therefore to look for isolated evidence to support my theory that the redshift occurs only for wavelengths much shorter than the average distance between two charges in the intergalactic plasma. As this is likely to be in the radio region, I had a look at the book 'Radio Recombination Lines' and found this (http://www.physicsmyths.org.uk/imgs/OQ208_1s.gif). The measurement clearly shows that the radio lines in this frequency band (6 GHz) are slightly less red-shifted than the indicated optical lines. More astonishingly, this circumstance is not even mentioned (let alone discussed) by the author (the article is about the occurence of radio recombination lines in extragalactic objects in general). Whatever the interpretation of this is, it goes to show that data are far from being adequately analyzed by cosmologists.
In the above article I found furthermore a reference regards the same object (Seyfert Galaxie OQ208) that reports different redshifts even within a rather narrow part of the visible spectrum (see here for an abstract (http://www.physicsmyths.org.uk/imgs/OQ208_2s.gif)). In this case it appears to be related to the damping of the spectral line, with the broader lines more redshifted then the narrow forbidden lines.
Unfortunately, it seems that there are not enough suitable data published that would enable one to investigate these points in a systematic sense, but it clearly demonstrates that the situation regards the Hubble Law is not nearly as clear cut as generally pretended by cosmologists.

Grey
2003-May-21, 09:32 PM
I don't get your point. Are saying that galaxies are not receding at all? If they are receding (which I take it you assume), then there should certainly be a Doppler shift; however the reverse is not necessarily true.
It's a subtle difference. The Doppler effect is the result of an object moving through space relative to us. In the case of the cosmological redshift, the object isn't moving away from us through space, but it's instead that space itself is expanding, carrying the galaxies away from each other, and this causes a lengthening of the wavelengths. The net result is comparable, but there are actually differences between the two, and kurtisw was quite right to point out that the two are not really the same thing.

This website give a slightly more detailed summary: http://curious.astro.cornell.edu/question.php?number=278 . Also, the calculations involved are slightly different.

dgruss23
2003-May-21, 09:59 PM
thomas wrote: In the above article I found furthermore a reference regards the same object (Seyfert Galaxie OQ208) that reports different redshifts even within a rather narrow part of the visible spectrum (see here for an abstract). In this case it appears to be related to the damping of the spectral line, with the broader lines more redshifted then the narrow forbidden lines.
Unfortunately, it seems that there are not enough suitable data published that would enable one to investigate these points in a systematic sense, but it clearly demonstrates that the situation regards the Hubble Law is not nearly as clear cut as generally pretended by cosmologists.

It does seem that this effect has been considered in more detail here (http://adsbit.harvard.edu/cgi-bin/nph-iarticle_query?db_key=AST&bibcode=1989ApJ...343...54S&letter=.&defaultprint=YES&whole_paper=YES&page=54&epage=54&send=PRINT&ext=.pdf).

Other relevant papers are found here (http://xxx.lanl.gov/abs/astro-ph/9904061) and
here (http://adsbit.harvard.edu/cgi-bin/nph-iarticle_query?db_key=AST&bibcode=1995ApJ...447..496C&letter=.&defaultprint=YES&whole_paper=YES&page=496&epage=496&send=PRINT&ext=.pdf).

Thomas
2003-May-22, 02:57 PM
I had a look at the book 'Radio Recombination Lines' and found this (http://www.physicsmyths.org.uk/imgs/OQ208_1s.gif). The measurement clearly shows that the radio lines in this frequency band (6 GHz) are slightly less red-shifted than the indicated optical lines
It occured to me now that the error for the redshift of the optical lines (vertical line in the first reference (http://www.physicsmyths.org.uk/imgs/OQ208_1s.gif)) has actually a value a few times the offset from the radio line, which might therefore be insignificant. However, as the displacement caused by the error could also be in the opposite direction, there is a 50/50 chance that the difference between the z-values in the optical and radio region might in fact be even larger than indicated in the diagram. Again, a more accurate measurement is needed here to resolve this question. Also, it might be required to use longer radio wavelengths (i.e. lower frequencies) to detect the difference to the optical z-value.

P.S.:I am having a bit of a break now until the beginning of June and won't be able to respond to posts within this time

Aldrin
2003-May-23, 03:02 AM
I came across a distance of the universe given by Arp in Seeing Red
"The whole observed extragalactic zoo--including quasars, BL LACs and faint cluster galaxies--is only about as distant as the Local Superclusters Virgo and Fornax, about 55 million light years. The next farthest objects may be very distant indeed, too faint for current telescopes to detect."

How he came with those numbers and conclusions?

http://www.quackgrass.com/roots/arp.html

Even more startling, redshifts are quantized; they tend to have certain discrete values: z = .061, .30, .60, .91, 1.41, 1.96, etc. K. G. Karlsson discovered a simple empirical formula (published in 1971!) which relates these special redshift values to each other. An extremely prominent redshift quantization corresponds to steps in apparent velocity of a mere 37.5 km/sec. This quantization is very significant, as it is completely washed out for galaxies with velocities greater than about 20 km/sec. Not only are galaxies not racing away from us, most of them are cosmic slowpokes! The universe is not expanding, it is close to static.

It follows from all this that we don't see nearly as far into the universe as conventionally thought; the immense distances contemplated by orthodoxy are artifacts of the orthodox interpretation of redshift. The whole observed extragalactic zoo--including quasars, BL LACs and faint cluster galaxies--is only about as distant as the Local Superclusters Virgo and Fornax, about 55 million light years. The next farthest objects may be very distant indeed, too faint for current telescopes to detect.

Dae
2003-May-23, 04:52 AM
OK, I am no Steven Hawking, but this is really getting far fetched. I am pleased to say that discussions here have made me question the rules, you guys are good conversion for amauter cosmologists. But from materials i've read , ive learned its all about perspective. As little beings in a huge universe, how can we expect that what we see represents the whole in general. We might need to step back in our theories, and maybe the mystery of the beginning and the before is just to complex for human minds, i mean hell, we only live only 100 years and cosmology has only been around like 100 or so years. (recent) That's why I take these theories lightly, and we all should. I think there is alot more to be discovered in the universe because current observations are disproving what was law 5 years ago. I love how the relation between the redshift of stars and its relation to doppler effect are questioned, although light may behave like waves it's not so easily dismissed as explained because it is particutate in nature. It is not a wave, only matter so small it behaves eratically in a way like a pressure wave, i believe.
Only recently has the expansion of the universe and the absence of matter to explain the observasion been observed. The universe cannot be explained with our current understading of nature.

Blow this off anyone, if you please. I am a poet, not a phycist. Steven Hawking say some mind blowing things though. like, what happens when the universe starts to receed? Do things happen in reverse but we precieve them as normal? There is alot we just dont know and could never explain because of our limited perspective. I love physics!

OK, now that I stopped typing ( and got another beer ) I realized I was flawed in my inference. I said presuure waves which are sound waves, which are not radio waves therefore my whole arguement is flawed, since radio waves and dopler effect could be related to light since both are electromagnetic radiation. But thats what i get for drinking and typing I guess.

Grey
2003-May-23, 01:20 PM
I came across a distance of the universe given by Arp in Seeing Red.
The review given (by the people that sell this book, it should be noted) has some amusing lines:

That orthodoxy has denied observing time on the big telescopes to Arp and others who make discordant observations. It has excluded their most important discoveries from major journals. As far as the popular press is concerned, this small heroic band of observers just don't exist; their observations go unreported.
Hmm, just like the Planet X believers, there's a whole conspiracy of the astronomical community to support the orthodox viewpoint. You know, every astronomer and physicist I know is excited when they discover something they weren't expecting. It should perhaps be remembered that the expanding universe was by no means expected. In fact, everyone had assumed the universe was static until they were forced by the observational evidence to acknowledge they might be wrong about that. It's not like anyone wanted an expanding universe and worked to make it so. The mainstream view was dragged, kicking and screaming, to that idea.


Narlikar's theory also abolishes curved space, that trademark of relativity, cliche of science fiction, and nemesis of all who attempt to visualize it. Astonishingly, merely by allowing masses to vary with time, one allows one's "space-time" to relax and lie flat, just as Euclid told us it must! ...A correct theory must have flat space and uniform time.
Hmm, sounds like someone has assumed the conclusion here.


Another hopeful sign is that Narlikar's theory predicts a stable universe. Relativity and Newton's theory of gravitation share the flaw of predicting that matter in a static universe governed by gravitation would fall in a heap. ...Consequently, for both Newton and Einstein the universe must either be blowing apart or collapsing. Both are hopeless doctrines for an eternal universe, which shows that these theories can't be extrapolated to the whole universe.
And again. Of course, if we assume from the beginning that space has to be flat, time has to be uniform, and the universe has to be eternal, why are we trying to create a theory? We've already decided what the answer will be...


The variable mass theory not only explains the Hubble relation for normal galaxies as due to "look-back" time, it gets the Hubble constant right on the first try! The variable mass theory calculates the Hubble constant from a single datum: the age of the oldest stars in our Milky Way, which are between 13 and 17 billion years old. From this age the variable mass theory calculates a Hubble constant between 39 and 51 km/sec/Megaparsec. The best observational values are between 42 and 56 km/sec/Mpc.
Well, it's nice that this works out. Of course, when he made that "first try", Arp already knew what the measured value for the Hubble constant was, so any theory he created had to get it right, or it wouldn't agree with experiment. This should be expected, not a pleasant surprise, and he can easily work with the numbers until it comes out the way he wants it. Now he needs to go predict some other easily measured quantities, and we can go do the experiment to see if it holds up.


We've heard a lot of blather in recent years telling us that there's nothing new to learn. We've heard about "the end of science," and about theories of everything. These pronouncements are symptomatic of the decay of today's academic science. They reflect today's academic rationalism, which holds that truth can be spun from mere words and symbols in defiance of observation. For those who turn their backs on reality, there is never anything new to be learned--and for them science is indeed at an end.
I do know of quotes from the turn of the last century thinking that all the major laws of science had been determined, and all that was left was refinement (except for a couple small problems like the photoelectric effect and the blackbody radiation spectrum :wink: ). But nobody today thinks that we're just a short distance away from discovering all there is to discover. I don't know where they heard this "blather" but it wasn't from the mainstream scientific community.

D J
2003-May-23, 10:27 PM
You know, every astronomer and physicist I know is excited when they discover something they weren't expecting. It should perhaps be remembered that the expanding universe was by no means expected. In fact, everyone had assumed the universe was static until they were forced by the observational evidence to acknowledge they might be wrong about that. It's not like anyone wanted an expanding universe and worked to make it so. The mainstream view was dragged, kicking and screaming, to that idea.


Here an observation who seem to contradict the expansion of the Universe

Hubble Pictures Too Crisp, Challenging Theories of Time and Space

Clarity is what astronomers and the public have come to expect from the Hubble Space Telescope. But the sharpness with which Hubble photographs distant galaxies has scientists pondering why the pictures are not blurry, as some new calculations suggest they should be, and whether some basic assumptions about space, time and gravity might have to be rethought.

http://www.space.com/scienceastronomy/quantum_bits_030402.html

What is the reaction of the mainstream about this?
Did they have some reactions comparable to:
"The mainstream view was dragged, kicking and screaming, to that idea."

Aldrin
2003-May-24, 06:12 PM
Here an observation who seem to contradict the expansion of the Universe

Hubble Pictures Too Crisp, Challenging Theories of Time and Space

Clarity is what astronomers and the public have come to expect from the Hubble Space Telescope. But the sharpness with which Hubble photographs distant galaxies has scientists pondering why the pictures are not blurry, as some new calculations suggest they should be, and whether some basic assumptions about space, time and gravity might have to be rethought.

http://www.space.com/scienceastronomy/quantum_bits_030402.html

What is the reaction of the mainstream about this?
Did they have some reactions comparable to:
"The mainstream view was dragged, kicking and screaming, to that idea.

Are you suggesting than cosmologists should return to the drawing board?
Bah! don`t count on it, they will ignore this new observation this is more easy than rethinking the whole theory.
:o

dgruss23
2003-May-25, 01:20 PM
Grey wrote: In fact, everyone had assumed the universe was static until they were forced by the observational evidence to acknowledge they might be wrong about that. It's not like anyone wanted an expanding universe and worked to make it so. The mainstream view was dragged, kicking and screaming, to that idea.

If anything the fact that the mainstream had to be dragged kicking and screaming to the expanding universe view would seem to support the contention that scientists can take on orthodox views of scientific theories. Why kick and scream? Shouldn't scientists be excited about new developments?

Arp's contention is that everyone is "assuming" that redshifts are predominately a function of expansion of the universe with superimposed peculiar motions. His observational results and the evidence of others working independent of him suggests that in some cases objects can have a component of their measured redshift that is not accounted for by expansion and peculiar motions.


:
The variable mass theory not only explains the Hubble relation for normal galaxies as due to "look-back" time, it gets the Hubble constant right on the first try! The variable mass theory calculates the Hubble constant from a single datum: the age of the oldest stars in our Milky Way, which are between 13 and 17 billion years old. From this age the variable mass theory calculates a Hubble constant between 39 and 51 km/sec/Megaparsec. The best observational values are between 42 and 56 km/sec/Mpc.


Grey wrote: Well, it's nice that this works out. Of course, when he made that "first try", Arp already knew what the measured value for the Hubble constant was, so any theory he created had to get it right, or it wouldn't agree with experiment. This should be expected, not a pleasant surprise, and he can easily work with the numbers until it comes out the way he wants it. Now he needs to go predict some other easily measured quantities, and we can go do the experiment to see if it holds up.

It is worth pointing out that the studies that Arp cites in favor of a Hubble Constant in the range of 42-56 km sec-1 were papers by Allan Sandage which were based upon a flawed assumption that M-31 and M101 were "average" sized galaxies for their morphological types. Using those two galaxies as single diameter calibrators he derived an H0 value too low. For example in this (http://adsbit.harvard.edu/cgi-bin/nph-iarticle_query?db_key=AST&bibcode=1993ApJ...402....3S&letter=.&defaultprint=YES&whole_paper=YES&page=3&epage=3&send=PRINT&ext=.pdf) paper Sandage finds a distance to NGC 4321 of 28 Mpc and thus derives a Hubble constant of 41 km sec-1 Mpc-1. Cepheids have given a distance to NGC 4321 of 15.2 Mpc and so Sandages argument fails.

In a more recent paper, Bell and Comeau (http://xxx.lanl.gov/PS_cache/astro-ph/pdf/0305/0305060.pdf) have derived a Hubble Constant of 58 after subtraction of intrinsic redshift components from the measured redshifts. Even if their analysis is disputed they make a critical point for the debate. IF intrinsic redshifts do in fact exist in normal galaxies, then the measured redshifts used to calculate H0 are too large and thus the derived values of the Hubble Constant are too high.

Grey
2003-May-27, 05:22 PM
If anything the fact that the mainstream had to be dragged kicking and screaming to the expanding universe view would seem to support the contention that scientists can take on orthodox views of scientific theories. Why kick and scream? Shouldn't scientists be excited about new developments?
I threw out an off-the-cuff description :) , but I actually think that there's an important distinction to be made here. Scientists, like everyone else, can have cherished beliefs and ideas. And there's a tendency to assume that one's own idea is the right one, so there can be a reluctance to leave it behind (see my previous post (http://www.badastronomy.com/phpBB/viewtopic.php?p=83615#83615) on the subject of having theories proven wrong). The discovery of an apparently expanding universe did indeed excite the scientific community, but many were very reluctant to let go of their preconceived ideas of a static cosmos. However, as evidence gathered, all but a few die-hards conceded that, indeed, that's the way the universe appeared to be. My point here is simply that evidence was and is pretty convincing, or the mainstream never would have been won over to the idea of an expanding universe in the first place.

Arp and similar folk, however, claim that the scientific community goes a significant step further than being reluctant to give up a preferred theory. They suggest that the mainstream cosmologists know that they're wrong, yet refuse to admit it. That there's a conspiracy to repress the contradictory evidence, so that the establishment can hold on to some kind of intellectual power. When I said "kicking and screaming" (and I was using hyperbole, here, of course :) ), I did not mean to imply that there was any kind of deliberate suppression of data or experimental results then, nor do I think that there's significant evidence for it now. I think it's a serious accusation against some folk for whom I have a great deal of respect.

dgruss23
2003-May-28, 01:30 AM
If anything the fact that the mainstream had to be dragged kicking and screaming to the expanding universe view would seem to support the contention that scientists can take on orthodox views of scientific theories. Why kick and scream? Shouldn't scientists be excited about new developments?
I threw out an off-the-cuff description :) , but I actually think that there's an important distinction to be made here. Scientists, like everyone else, can have cherished beliefs and ideas. And there's a tendency to assume that one's own idea is the right one, so there can be a reluctance to leave it behind (see my previous post (http://www.badastronomy.com/phpBB/viewtopic.php?p=83615#83615) on the subject of having theories proven wrong).

There's not doubt that scientists have cherished beliefs. Certainly the challenge is to remain objective in the face of those beliefs. I was thinking of "kicking and screaming" to mean after the evidence became apparent, but as you describe it above is not such a big deal.


Arp and similar folk, however, claim that the scientific community goes a significant step further than being reluctant to give up a preferred theory. They suggest that the mainstream cosmologists know that they're wrong, yet refuse to admit it.

I would agree that there is not a systematic effort to suppress evidence by the mainstream astronomical community. The mainstream certainly thinks the Big Bang is correct and thus would not see themselves as suppressing alternative views.

However, at the refereeing level, individual referees can make questionable choices. Some referee's are tolerant of alternative views and others are not.

Manchurian Taikonaut
2004-Mar-17, 04:43 PM
http://energy.phys.ncku.edu.tw/~astrolab/mirrors/apod/image/0403/z10_vlt_big.jpg
Distant Quasar? New Galaxy record distance broken by far away object?
http://antwrp.gsfc.nasa.gov/apod/image/000...qso582_sdss.gif

http://antwrp.gsfc.nasa.gov/apod/image/040...z10_vlt_big.jpg

Is this another object found past the edge of our universe again, a new object found out past the end of our know universe out beyond the universe's dark edge? Is this a Quasar, has the galaxy's distance record broken again? Are these mysterious objects getting powered by Anti-Gravity, driving themselves beyond the edge of our know universe? What is it?

Hamlet
2004-Mar-17, 06:16 PM
Are these mysterious objects getting powered by Anti-Gravity, driving themselves beyond the edge of our know universe? What is it?

These objects are being carried along by the uniform expansion of the universe resulting from the Big Bang. It's only anti-gravity in the sense that it is expanding the universe as opposed to it collapsing under the gravitational influence of matter and energy.

There has been evidence over the last 6 years that the expansion has been accelerating due to what is now called "dark energy". However, since no one really knows what dark energy is, it's premature to speak of it as anti-gravity.