Big Bang

In article ,
Jonathan Doolin writes:
If you have a literal "big bang" you will not see smoking remains at
the center, because you ARE the center.

I'm afraid I don't follow this at all. Your model, as I understand
it, has galaxies expanding from a fixed point into pre-existing
space. That implies, to me, a definite center.

As for redshifts between 0.5 and 2, I used z+1 =3D sqrt[(1+v/c)/(1-v/c)]

That's a redshift-velocity relation. What I asked you to compute was
a redshift-*distance* relation. In particular, you need the
luminosity distance, which is not the same as the proper distance.
(Both are a little tricky to compute.) I'm not convinced the
relation isisotropic, and I doubt very much it will agree with
observation (principally the supernova results).

As I said, it is a very rough sketch. Even without any numbers, the
point I was trying to make was that any large acceleration along the
way has a large effect on our final view of the universe.

I suggest you consider an unacellerated model first.

(I must have said something here that didn't make sense to you. Were
you unfamiliar with the idea that when you make a relativistic
acceleration toward a body, that it lurches away from you, then
appears to approach superluminally?)

I don't know what a "relativistic acceleration" is, and I am most
certainly unfamiliar with the idea that a body "lurches away" if you
accelerate towards it. Please show me the math.

What any of this has to do with Mach's Principle is also a mystery to
me.

Are you saying, then, that as soon as gravity is involved, you no
longer apply special relativity?

If space curvature is significant, you have to take it into account.
For most purposes, it only matters if gravity is very strong or
measurements are very precise.

Mach's Principle says that we are not competent to
determine the nature of motion of bodies 100 billion light years from
here,

That's certainly news to me.

Likewise, my relative rapidity with objects 100 billion light years
away changes just the same as my relative rapidity with the objects
right in front of me, when I accelerate toward them. Thus it will all
be subject to the same prescription for coordinate transformation.

I don't think anybody disagrees with that, and I don't see that it
has anything to do with Mach's Principle.

I realizethere are 75 years of Standard Cosmology proponents who all
disagree, but they have built their science up from this foundation of
Mach's Principle--i.e. no foundation at all.

Once again, I invite you to identify a single observation that would
differ depending on whether Mach's Principle is true or false.

--
Help keep our newsgroup healthy; please don't feed the trolls.
Steve Willner Phone 617-495-7123
Cambridge, MA 02138 USA

On Jul 16, 8:50*am, Antares 531 wrote:
Was the "Big Bang" an explosive event, similar to a thermonuclear
bomb, or was it a matter of unrolling the three dimensions we now
perceive as identifying our space?

Unrolling the dimensions, from a perspective within this universe, may
have been a smooth, gentle process that would not have produced the
inferno that most Big Bang ideas are built around.

Gordon

It depends on what you call smooth and gentle process.
The conventional Big Bang does not contain a shock front. There was
no shock wave, as seen when an explosive on earth goes off. On a large
scale, the process was smooth.
On the largest scales the universe seemed isotropic soon after the
Big Bang. Thus, the process could be pictured as being extremely
smooth, the way the surface of the earth seems "smooth" if the earth
is show in true scale. Just because the mountains look large to us
doesn't mean they are significant relative to the entire earth. A
"small" anisotropy on the scale of the earth means a major
geographical feature on the scale of human beings.
The universe couldn't have been completely smooth, or else we
wouldn't have galaxies. There must have been small scale anisotropy. I
think the nature of this anisotropy is the main issue in cosmology,
astronomy, and physics.
However, the process seems to have been high turbulent. There
seem to have been a large number of eddies early in the universe.
These "eddies" would have been small compared to the radius of the
universe, but they have a significant effect on galactic history.
I think the words "Big Bang" are misleading since there is no
shock wave that constitutes a front. Perhaps the "Big Blending" would
be more descriptive. When you try to whip up a fluid with a blender,
the fluid may puff up due to air bubbles. However, the effect is still
smooth.

On Aug 18, 5:44*pm, (Steve Willner) wrote:
In article ,
*Jonathan Doolin writes:

If you have a literal "big bang" you will not see smoking remains at
the center, because you ARE the center.

I'm afraid I don't follow this at all. *Your model, as I understand
it, has galaxies expanding from a fixed point into pre-existing
space. *That implies, to me, a definite center.


Not a fixed point--a fixed event. A fixed "point" in space is
stationary in only one reference frame. On the other hand, a fixed
event can be the center of an expanding sphere in any and every
reference frame.

As for redshifts between 0.5 and 2, I used z+1 =3D sqrt[(1+v/c)/(1-v/c)]

That's a redshift-velocity relation. *What I asked you to compute was
a redshift-*distance* relation. *In particular, you need the
luminosity distance, which is not the same as the proper distance.
(Both are a little tricky to compute.) *I'm not convinced the
relation isisotropic, and I doubt very much it will agree with
observation (principally the supernova results).


I don't have access to much of that data. I'd need to have the data
categorized by type, luminosity, redshift, direction (relative to the
dipole anisotropy), etc. But they don't have that! They have the
Hubble Deep Field in two extremely narrow paths HDF North and HDF
South, I think they call it. It might be possible to get an idea and
triangulate from three or four directions, but not with just two.

As I said, it is a very rough sketch. *Even without any numbers, the
point I was trying to make was that any large acceleration along the
way has a large effect on our final view of the universe.

I suggest you consider an unacellerated model first.


The unaccelerated model:

http://en.wikipedia.org/wiki/File:Milne_Model.jpg

http://en.wikipedia.org/wiki/Talk:Mi...del#correction

(I must have said something here that didn't make sense to you. *Were
you unfamiliar with the idea that when you make a relativistic
acceleration toward a body, that it lurches away from you, then
appears to approach superluminally?)

I don't know what a "relativistic acceleration" is, and I am most
certainly unfamiliar with the idea that a body "lurches away" if you
accelerate towards it. *Please show me the math.


What I meant by a relativistic acceleration is one where the change in
velocity is close to the speed of light. The math is shown he
http://en.wikipedia.org/wiki/Lorentz_transformation

What you should do is apply the transform to an event in the past
(x=0, t0). That event will move further into the past, and away from
x=0. If that event represents the origin of an expanding sphere, the
sphere will be larger, in direct proportion to how far the event moved
into the past.

As for objects "lurching away," to see it in the usual sense, you have
to accelerate toward a receding body. I don't have a neat copy of
"the math" anywhere, but some time ago, I did create a java applet
that might help.

http://www.wiu.edu/users/jdd109/stuf...tivity/LT.html

What any of this has to do with Mach's Principle is also a mystery to me.

Are you saying, then, that as soon as gravity is involved, you no
longer apply special relativity?

If space curvature is significant, you have to take it into account.
For most purposes, it only matters if gravity is very strong or
measurements are very precise.

*Mach's Principle says that we are not competent to
determine the nature of motion of bodies 100 billion light years from
here,

That's certainly news to me.


I might be overgeneralizing whatever Mach's Principle is. There was
an experiment (of Newton's I think) involving water in a spinning pail
of water, and Mach said that we are not competent to predict results
for the experiment if the walls of the vessel were made several
leagues thick.

To be honest, I don't think there is a precise way of stating Mach's
Principle--it isn't a Principle by which you can actually predict
anything--It is a only a principle by which you justify ignorance.

Likewise, my relative rapidity with objects 100 billion light years
away changes just the same as my relative rapidity with the objects
right in front of me, when I accelerate toward them. *Thus it will all
be subject to the same prescription for coordinate transformation.

I don't think anybody disagrees with that, and I don't see that it
has anything to do with Mach's Principle.


Hmmm, I'll have to track down some quotes for you. But I've heard
people say

"Most physicists believe Special Relativity is only valid locally,
while general relativity is valid everywhere."

"The effects of Lorentz Transformations are not really real."

"You are introducing this lurching away effect which is totally non-
physical; only mathematical."

I realizethere are 75 years of Standard Cosmology proponents who all
disagree, but they have built their science up from this foundation of
Mach's Principle--i.e. no foundation at all.

Once again, I invite you to identify a single observation that would
differ depending on whether Mach's Principle is true or false.

--
Help keep our newsgroup healthy; please don't feed the trolls.
Steve Willner Phone 617-495-7123
Cambridge, MA 02138 USA

I can't identify a single such observation, because Mach's Principle
is in the "not even wrong" category. As far as I know, it is just
used as an excuse for ignoring the Lorentz Transformations--They only
pretend to use Mach's Principle as a mathematical or logical
motivation in any scientific discourse.

Jonathan Doolin* *

SW There are certainly
SW written descriptions of what the "traveling twin" sees

In article ,
Jonathan Doolin writes:
I am looking over the article in Wikipedia on "Twin Paradox"

That's hardly the only reference around. One article I particularly
remember was in _Mercury_ magazine at least 20 years ago, and I'm
pretty sure I've seen the same treatment in textbooks.

In the article, there are three space-time diagrams, but all of them
are in the reference frame of the stationary twin. There are two
other reference frames which should be shown as well--that of the
traveling twin on his outbound journey, and that of the traveling twin
on his inbound journey.

You really only need the first of those reference frames to see
what's going on. It has to be an inertial reference frame, so it
keeps going when the travelling twin turns around. The travelling
twin is now moving faster in this reference frame than the stay-at-
home twin and thus ages slower.

You can also think about each twin sending clock pulses that
propagate at the speed of light. If you count the pulses each twin
receives from the other, you'll get the right answer.

Once you understand it, feel free to improve the Wikipedia article.
I think your suggestions for additional explanation have merit.

... "Principle of Equivalence" hogwash

Which experiment does this "hogwash" predict incorrectly?

apparently, all Einstein wanted to do
once he figured out the special theory of relativity is to find some
excuse to reject its use.

That's certainly news to me! General relativity leads to special
relativity when space curvature can be neglected.

--
Help keep our newsgroup healthy; please don't feed the trolls.
Steve Willner Phone 617-495-7123
Cambridge, MA 02138 USA

On Aug 23, 5:46*pm, (Steve Willner) wrote:
SW There are certainly
SW written descriptions of what the "traveling twin" sees

In article ,
*Jonathan Doolin writes:

I am looking over the article in Wikipedia on "Twin Paradox"

That's hardly the only reference around. *One article I particularly
remember was in _Mercury_ magazine at least 20 years ago, and I'm
pretty sure I've seen the same treatment in textbooks.

In the article, there are three space-time diagrams, but all of them
are in the reference frame of the stationary twin. *There are two
other reference frames which should be shown as well--that of the
traveling twin on his outbound journey, and that of the traveling twin
on his inbound journey.

You really only need the first of those reference frames to see
what's going on. *It has to be an inertial reference frame, so it
keeps going when the travelling twin turns around. *The travelling
twin is now moving faster in this reference frame than the stay-at-
home twin and thus ages slower.

You can also think about each twin sending clock pulses that
propagate at the speed of light. *If you count the pulses each twin
receives from the other, you'll get the right answer.

Once you understand it, feel free to improve the Wikipedia article.
I think your suggestions for additional explanation have merit.


It's a work in progress.

http://en.wikipedia.org/wiki/Talk:Tw...ference_Frames

http://demonstrations.wolfram.com/pr...ForTwinParadox


... "Principle of Equivalence" hogwash

Which experiment does this "hogwash" predict incorrectly?


Based on what I have read, I am actually not able to determine whether
the Principle of Equivalence is "hogwash." I shouldn't have said
that, perhaps.

However, what I have heard *about* the principle of equivalence is a
great and grave overgeneralization; primarily that gravity is
equivalent to acceleration.

I would be prepared to acknowledge that it is highly likely that the
behavior of free-falling bodies in the region where F=m*g would be
effectively equivalent to the behavior of inertial bodies as viewed by
an observer on an accelerated platform accelerating at a rate of a=g
on the approach.

Of course, once the accelerating platform PASSES the inertial body,
you have the acceleration going the WRONG WAY, and any resemblance
between acceleration and gravity is now gone.

Also, if you are in a larger region, such that F= G m1 * m2 / r^2, the
motion of bodies falling in this volume is NOT equivalent to the
motion you would see if you were on a platform accelerating toward
them.

On the other hand, I could imagine trying an approach to determine the
speed of the clock of an observer on an accelerating platform, and
somehow relating this to the speed of a clock of an observer standing
on the ground in a gravitational field. In this one small way, (speed
of clock), gravitational field and acceleration may be equivalent.
But to whom?

You need to produce the inertial observer from whose viewpoint the two
clocks give this ratio. You need to have an initial velocity and a
final velocity of the accelerated clock in the frame of reference of
this inertial observer. You need to have a particular scale of time
between the initial and final velocity.

I may have the opportunity to work on this question some more and come
to a better conclusion than "hogwash."

Jonathan Doolin

apparently, all Einstein wanted to do
once he figured out the special theory of relativity is to find some
excuse to reject its use.

That's certainly news to me! *General relativity leads to special
relativity when space curvature can be neglected.

--
Help keep our newsgroup healthy; please don't feed the trolls.
Steve Willner * * * * * *Phone 617-495-7123 * *
Cambridge, MA 02138 USA * * * * * * * *

On Aug 26, 4:31*pm, Jonathan Doolin wrote:
On Aug 23, 5:46*pm, (Steve Willner) wrote:



SW There are certainly
SW written descriptions of what the "traveling twin" sees

In article ,
*Jonathan Doolin writes:

I am looking over the article in Wikipedia on "Twin Paradox"

That's hardly the only reference around. *One article I particularly
remember was in _Mercury_ magazine at least 20 years ago, and I'm
pretty sure I've seen the same treatment in textbooks.

In the article, there are three space-time diagrams, but all of them
are in the reference frame of the stationary twin. *There are two
other reference frames which should be shown as well--that of the
traveling twin on his outbound journey, and that of the traveling twin
on his inbound journey.

You really only need the first of those reference frames to see
what's going on. *It has to be an inertial reference frame, so it
keeps going when the travelling twin turns around. *The travelling
twin is now moving faster in this reference frame than the stay-at-
home twin and thus ages slower.

You can also think about each twin sending clock pulses that
propagate at the speed of light. *If you count the pulses each twin
receives from the other, you'll get the right answer.

Once you understand it, feel free to improve the Wikipedia article.
I think your suggestions for additional explanation have merit.

It's a work in progress.

http://en.wikipedia.org/wiki/Talk:Tw...ference_Frames

http://demonstrations.wolfram.com/pr...929/000002/Lor...

... "Principle of Equivalence" hogwash

Which experiment does this "hogwash" predict incorrectly?

Based on what I have read, I am actually not able to determine whether
the Principle of Equivalence is "hogwash." *I shouldn't have said
that, perhaps.

However, what I have heard *about* the principle of equivalence is a
great and grave overgeneralization; primarily that gravity is
equivalent to acceleration.

I would be prepared to acknowledge that it is highly likely that the
behavior of free-falling bodies in the region where F=m*g would be
effectively equivalent to the behavior of inertial bodies as viewed by
an observer on an accelerated platform accelerating at a rate of a=g
on the approach.

Of course, once the accelerating platform PASSES the inertial body,
you have the acceleration going the WRONG WAY, and any resemblance
between acceleration and gravity is now gone.

Also, if you are in a larger region, such that F= G m1 * m2 / r^2, the
motion of bodies falling in this volume is NOT equivalent to the
motion you would see if you were on a platform accelerating toward
them.

On the other hand, I could imagine trying an approach to determine the
speed of the clock of an observer on an accelerating platform, and
somehow relating this to the speed of a clock of an observer standing
on the ground in a gravitational field. *In this one small way, (speed
of clock), gravitational field and acceleration may be equivalent.
But to whom?

You need to produce the inertial observer from whose viewpoint the two
clocks give this ratio. *You need to have an initial velocity and a
final velocity of the accelerated clock in the frame of reference of
this inertial observer. *You need to have a particular scale of time
between the initial and final velocity.

I may have the opportunity to work on this question some more and come
to a better conclusion than "hogwash."

Jonathan Doolin

apparently, all Einstein wanted to do
once he figured out the special theory of relativity is to find some
excuse to reject its use.

That's certainly news to me! *General relativity leads to special
relativity when space curvature can be neglected.

--
Help keep our newsgroup healthy; please don't feed the trolls.
Steve Willner * * * * * *Phone 617-495-7123 * *
Cambridge, MA 02138 USA * * * * * * * *

I have re-posted much of this comment along with some additional
thoughts and mathematics at

http://www.physicsforums.com/showthr...14#post2855214

In article ,
Jonathan Doolin writes:
However, what I have heard *about* the principle of equivalence is a
great and grave overgeneralization; primarily that gravity is
equivalent to acceleration.

Some of your questions will take more time than I have to answer, but
the above is easy. The equivalence principle says that no _local
experiment_ can distinguish between gravity and acceleration. If you
do non-local experiments -- which means using a large enough
"laboratory" that tidal forces are measurable -- of course the two
can be distinguished.

This is analogous to the principle of relativity, which says that no
_local experiment_ can distinguish any constant velocity. Of course
if you "look outside the window," you can measure velocity with
respect to something else.

I haven't checked the Wikipedia article(s), but I'll be surprised if
there's any disagreement with the above.

--
Help keep our newsgroup healthy; please don't feed the trolls.
Steve Willner Phone 617-495-7123
Cambridge, MA 02138 USA

On Aug 27, 5:33*pm, (Steve Willner) wrote:
In article ,
*Jonathan Doolin writes:

However, what I have heard *about* the principle of equivalence is a
great and grave overgeneralization; primarily that gravity is
equivalent to acceleration.

Some of your questions will take more time than I have to answer, but
the above is easy. *The equivalence principle says that no _local
experiment_ can distinguish between gravity and acceleration. *If you
do non-local experiments -- which means using a large enough
"laboratory" that tidal forces are measurable -- of course the two
can be distinguished.

This is analogous to the principle of relativity, which says that no
_local experiment_ can distinguish any constant velocity. *Of course
if you "look outside the window," you can measure velocity with
respect to something else.

I haven't checked the Wikipedia article(s), but I'll be surprised if
there's any disagreement with the above.

--
Help keep our newsgroup healthy; please don't feed the trolls.
Steve Willner * * * * * *Phone 617-495-7123 * *
Cambridge, MA 02138 USA * * * * * * * *

That all sounds reasonable.

And at least I've got the question out the

http://www.physicsforums.com/showthr...14#post2855214

Either someone will come along and answer it, or one morning I'll wake
up with the wherewithal to solve it myself. It's challenging my own
preconceived ideas (not enough to give up Milne's model, but enough to
wonder about some other things.)

Jonathan Doolin

In article ,
Jonathan Doolin writes:
Not a fixed point--a fixed event. A fixed "point" in space is
stationary in only one reference frame. On the other hand, a fixed
event can be the center of an expanding sphere in any and every
reference frame.

OK, I see what you mean, I think. There may still be a difficulty
with the cosmological principle -- that the Earth is not in any
special place -- but I'm not sure the model is ruled out on that
basis by existing observations.

SW What I asked you to compute was
SW a redshift-*distance* relation

We can do that now: the Hubble law distance is just proportional to
velocity, and I don't see why the luminosity distance (in a flat
Universe) wouldn't have the same 1+z correction as in the standard
model. This is not the same distance law as the standard model
gives, but perhaps you could put in curvature or something to make it
agree. Of course you also have to find agreement with such things as
the fluctuations in the microwave background.

Basically, either your model will give the same predictions as the
standard model -- in which case why bother? -- or it will give
different ones. If the latter, it would be rather surprising for
them to agree with observations, given how well the standard model
fits everything. But I've been wrong before, so feel free to do the
math and compare with observation.

SW I doubt very much it will agree with
SW observation (principally the supernova results).

I don't have access to much of that data.

The supernova data, at least a good quantity to work with, are online
in nicely calibrated form.

They have the Hubble Deep Field in two extremely narrow paths HDF
North and HDF South,

I'm not sure there are _any_ SNe in the deep fields, but there are
surely not many.


Other than the above comments on the astronomy, I'll suggest that if
you want to learn relativity, you should get a textbook. Or more
than one. One of the best suggestions I was ever given was that
(special) relativity is tricky the first time you see it, and it's
very helpful to have the same equations explained in different words.
As I recall, some of the books I personally found most helpful were
written by Minkowski in the 1930s, but my memory may be faulty about
the author and/or the date. Anyway _for me_, the older books were
more helpful than newer ones, but it could easily be the reverse for
someone else.

--
Help keep our newsgroup healthy; please don't feed the trolls.
Steve Willner Phone 617-495-7123
Cambridge, MA 02138 USA

On Sep 1, 3:22*pm, (Steve Willner) wrote:
In article ,
*Jonathan Doolin writes:

Not a fixed point--a fixed event. *A fixed "point" in space is
stationary in only one reference frame. *On the other hand, a fixed
event can be the center of an expanding sphere in any and every
reference frame.

OK, I see what you mean, I think. *There may still be a difficulty
with the cosmological principle -- that the Earth is not in any
special place -- but I'm not sure the model is ruled out on that
basis by existing observations.

SW What I asked you to compute was
SW a redshift-*distance* relation

We can do that now: the Hubble law distance is just proportional to
velocity, and I don't see why the luminosity distance (in a flat
Universe) wouldn't have the same 1+z correction as in the standard
model. *This is not the same distance law as the standard model
gives, but perhaps you could put in curvature or something to make it
agree. *Of course you also have to find agreement with such things as
the fluctuations in the microwave background.


What I would probably be interested in is developing a directional
model, which would be in line with the dipole anisotropy; I guess that
would be a simple rotation trasform, so right ascention and
declination became a polar and azimuthal angle in line with the dipole
axis.

Then I would look for explanations of a couple of anomolies:

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

Please, click on the link and look at the top graph. There appears to
be an outlier around 7 GPc, and then there is an extremely wide error
bar between 9 and 12 GPc. This particular chart seems to top out at
c*z=500000km/s, which is z=5/3.

With a high variation of distance, and a very low variation of
redshift, This would seem to indicate that there is a thick shell of
supernova that are all traveling away from us at essentially the same
speed.

I think that is consistent with some of the ascii space-time diagrams
I drew earlier, if we have scattering from multiple events, then the
shell of constant velocity would be fairly symmetrical.

\ \ | / /
\ \ | / /
\ \ / / /
\ \ / / /
\ \/ / /
\ \ / /
\ \/\ / /
\/ \/
\ /
\ /

....whereas if we have scattering from a more singular event, that
shell will be thinner on one side than the other:

\ \ | / /
\ \ | / /
\ \ | / /
\ \ / / /
\ \/ / /
\ \ / /
\ \/ /
\/ /
\ /
\ /

For an explanation of the outlier at the 7 GPc mark; you have a region
where you have a fast-moving surface of supernovae--all much closer
than would otherwise be expected. That points to a recent event; an
explosion which "created" our local universe. Those events would
probably constitute the latest division in either of my space-time
diagrams above.

With data compiled by others, though, all I can really do is speculate
on what it means, but it still kind of seems to fit with this model.

Basically, either your model will give the same predictions as the
standard model -- in which case why bother? -- or it will give
different ones. *If the latter, it would be rather surprising for
them to agree with observations, given how well the standard model
fits everything. *But I've been wrong before, so feel free to do the
math and compare with observation.

SW I doubt very much it will agree with
SW observation (principally the supernova results).

I don't have access to much of that data.

The supernova data, at least a good quantity to work with, are online
in nicely calibrated form.


Ostensibly, that data is available he

http://www.cfa.harvard.edu/supernova/SNarchive.html

If I were a computer hacker, maybe I would be able to access it.

Jonathan Doolin

*They have the Hubble Deep Field in two extremely narrow paths HDF
North and HDF South,

I'm not sure there are _any_ SNe in the deep fields, but there are
surely not many.

Other than the above comments on the astronomy, I'll suggest that if
you want to learn relativity, you should get a textbook. *Or more
than one. *One of the best suggestions I was ever given was that
(special) relativity is tricky the first time you see it, and it's
very helpful to have the same equations explained in different words.
As I recall, some of the books I personally found most helpful were
written by Minkowski in the 1930s, but my memory may be faulty about
the author and/or the date. *Anyway _for me_, the older books were
more helpful than newer ones, but it could easily be the reverse for
someone else.

--
Help keep our newsgroup healthy; please don't feed the trolls.
Steve Willner * * * * * *Phone 617-495-7123 * *
Cambridge, MA 02138 USA * * * * * * * *