| Topic: |
Science > Physics |
| User: |
"Rob Dekker" |
| Date: |
18 Jan 2005 04:45:24 AM |
| Object: |
Inflationary Theory ; I'm confused |
Over the past couple of years, I've read various articles
about the Big Bang Theory. Part of that is a theory
proposed by Groth, which states that the early Universe went
through a period of very rapid expansion called 'inflation'.
I understand that the inflation theory was
invented to explain the 'flat-ness' of space and the
MBR isotropy (microwave background indicates that
the early Universe had a very consistent high temperature).
I am confused about this inflationary period.
I've read somewhere that the Universe expanded to
a size of 40 million light years within a miniscule time.
This would clearly violate the limitation of the speed
of light.
I don't see why a speed-of-light violation would be needed :
Why would there be any observable difference between
a Universe expanding at speed of light and a Universe
that expands faster than that ?
I've read somewhere else that the Universe expanded
from almost a point to (only) 1 meter in size after the
inflatory period of 10^-32 sec. But a 1 meter ball of fire
would probably be very consistent in temperature, which
was the original reason to invent inflation theory.
So either way (1 meter or 40 million light-years) I don't
see what inflation theory is actually explaining beyond
a Universe which expands at light speed.
Can anyone shed some light on this ?
Thanks
Rob
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| User: "Sam Wormley" |
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| Title: Re: Inflationary Theory ; I'm confused |
18 Jan 2005 09:45:35 AM |
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Rob Dekker wrote:
Over the past couple of years, I've read various articles
about the Big Bang Theory. Part of that is a theory
proposed by Groth,
Alan Guth
which states that the early Universe went
through a period of very rapid expansion called 'inflation'.
I understand that the inflation theory was
invented to explain the 'flat-ness' of space and the
MBR isotropy (microwave background indicates that
the early Universe had a very consistent high temperature).
I am confused about this inflationary period.
I've read somewhere that the Universe expanded to
a size of 40 million light years within a miniscule time.
This would clearly violate the limitation of the speed
of light.
Can objects move away from us faster than the speed of light?
http://www.astro.ucla.edu/~wright/cosmology_faq.html#FTL
I don't see why a speed-of-light violation would be needed :
Why would there be any observable difference between
a Universe expanding at speed of light and a Universe
that expands faster than that ?
I've read somewhere else that the Universe expanded
from almost a point to (only) 1 meter in size after the
inflatory period of 10^-32 sec. But a 1 meter ball of fire
would probably be very consistent in temperature, which
was the original reason to invent inflation theory.
So either way (1 meter or 40 million light-years) I don't
see what inflation theory is actually explaining beyond
a Universe which expands at light speed.
.
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| User: "Rob Dekker" |
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| Title: Re: Inflationary Theory ; I'm confused |
18 Jan 2005 02:47:43 PM |
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"Sam Wormley" <swormley1@mchsi.com> wrote in message news:zaaHd.12720$EG1.5271@attbi_s53...
Rob Dekker wrote:
Over the past couple of years, I've read various articles
about the Big Bang Theory. Part of that is a theory
proposed by Groth,
Alan Guth
Thanks ! Sorry for misspelling his name.
which states that the early Universe went
through a period of very rapid expansion called 'inflation'.
I understand that the inflation theory was
invented to explain the 'flat-ness' of space and the
MBR isotropy (microwave background indicates that
the early Universe had a very consistent high temperature).
I am confused about this inflationary period.
I've read somewhere that the Universe expanded to
a size of 40 million light years within a miniscule time.
This would clearly violate the limitation of the speed
of light.
Can objects move away from us faster than the speed of light?
http://www.astro.ucla.edu/~wright/cosmology_faq.html#FTL
I think you are saying that since the time ran much slower in the
very early Universe than it does now, that therefor objects seem
to move away from us faster than light, but in reality we just see
them in their pre-birth state (right after BB). Right ?
I don't see why a speed-of-light violation would be needed :
Why would there be any observable difference between
a Universe expanding at speed of light and a Universe
that expands faster than that ?
I've read somewhere else that the Universe expanded
from almost a point to (only) 1 meter in size after the
inflatory period of 10^-32 sec. But a 1 meter ball of fire
would probably be very consistent in temperature, which
was the original reason to invent inflation theory.
So either way (1 meter or 40 million light-years) I don't
see what inflation theory is actually explaining beyond
a Universe which expands at light speed.
.
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| User: "Jim Black" |
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| Title: Re: Inflationary Theory ; I'm confused |
19 Jan 2005 07:04:19 PM |
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Rob Dekker wrote:
"Sam Wormley" <swormley1@mchsi.com> wrote in message
news:zaaHd.12720$EG1.5271@attbi_s53...
Rob Dekker wrote:
I am confused about this inflationary period.
I've read somewhere that the Universe expanded to
a size of 40 million light years within a miniscule time.
This would clearly violate the limitation of the speed
of light.
Can objects move away from us faster than the speed of light?
http://www.astro.ucla.edu/~wright/cosmology_faq.html#FTL
I think you are saying that since the time ran much slower in the
very early Universe than it does now, that therefor objects seem
to move away from us faster than light, but in reality we just see
them in their pre-birth state (right after BB). Right ?
No, that's not what he's saying. I don't even think it's meaningful to
compare the rate of time passage at two different times in history.
Such a comparison is only meaningful for two objects that go different
places and come back together. If you carefully define what it means
for two events at different places to be simultaneous, you can also
compare the time rates at the two places, but the answer you get can
depend on the definition of simultaneity chosen.
Special relativity defines distance as it would be measured by rulers
at rest relative to an observer, and time as it would be measured by
clocks at rest relative to an observer. It defines an event near an
observer to be simultaneous with a distant event if the nearby event
occurs halfway between the time light needed to have left the observer
to reach the distant event and the time light from the distant event
arrives.
In cosmology, distance is usually defined as it would be measured by
rulers at rest relative to the expanding universe (i.e. at rest
relative to most galaxies, the average momentum of the cosmic
background radiation, etc.). Time is defined as it would be measured
by clocks at rest relative to the expanding universe. Two events are
defined to be simultaneous if the age of the universe as measured by
such clocks was the same at both events.
The definitions of distance, time, and simultaneity are all different.
All of these concepts factor in to the determination of the velocity of
an object.
Special relativity assumes flat space-time. It assumes that lines that
are parallel at one place are parallel along their entire length, and
that non-accelerating objects at rest relative to one another are at
rest relative to each other forever. For down-to-earth purposes, the
first assumption is almost exactly true. The second is nowhere near
true if we use general relativity's definition of proper acceleration,
but it can be made almost exactly true by defining freely falling
objects to be accelerating downward. But over cosmological distances,
both assumptions fail miserably.
The consequence of this is that one must be careful when using special
relativity in cosmology. Does special relativity fail? In general,
yes. But along a narrow path at a specific time, or in a small volume,
the errors introduced are insignificant. One can still compare
velocities of distant objects using the special relativistic
definitions, but the answer you get depends on the path between the two
objects on which you apply the assumptions and definitions of special
relativity, and the specific time you are applying them at each point
along the path.
Thus, you can and will get multiple answers from special relativity
when applied to cosmology. However, none of the velocities you can
calculate using its definitions will be greater than the speed of
light.
But using the common cosmological definitions of distance, time, and
simultaneity I mentioned, the rate of change on the distance to a
far-away object can exceed the speed of light. The reasons for the
discrepancy between this speed and the object's velocity relative to us
according to special relativity are:
1. By the special relativistic definitions, those rulers at rest
relative to the expanding universe are moving away from us and thus
undergo length contraction. This works to reduce the change of the
distance from us to a far-away object and us as defined by special
relativity.
2. By the special relativistic definitions, the clocks at rest
relative to the expanding universe are moving away from us and thus
undergo time dilation. This can make the time the object was moving,
as defined by special relativity, longer than it is when using the
cosmological definition.
3. It might seem that effect #2 could be circumvented by measuring the
time at our location instead of the moving objects'. But the events
cosmology would define as happening in our present, would, by the
special relativistic definitions, be happening in the future. This
discrepancy increases as objects become more distant. Thus, distant
events that occur a short time apart as calculated using our clocks and
the cosmological definition of simultaneity, occur later and further
apart as measured by our clocks using the special relativistic
definition.
If you're interested, I would recommend looking over Ned Wright's
tutorial, since he explains a lot of this stuff well in simple terms,
and he has some good illustrations, which are worth much more than a
thousand words. The tutorial website is here:
http://www.astro.ucla.edu/~wright/cosmo_01.htm
You should especially look at the diagram in part 2, where he shows how
a space-time diagram of a nearly empty expanding universe using special
relativistic coordinates differs from the previous diagram using
cosmological coordinates:
http://www.astro.ucla.edu/~wright/cosmo_02.htm#DH
This illustrates what's going on pretty well, and does so much better
than I could ever try to do with words.
.
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| User: "Rob Dekker" |
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| Title: Re: Inflationary Theory ; I'm confused |
27 Jan 2005 01:10:59 AM |
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Hi Jim,
Thanks again for your write-up.
I read a lot more about cosmology now,
and I have some new notes below.
Rob
"Jim Black" <ghytrfvbnmju7654@mail.com> wrote in message news:1106183059.902285.122470@c13g2000cwb.googlegroups.com...
[...]
I think you are saying that since the time ran much slower in the
very early Universe than it does now, that therefor objects seem
to move away from us faster than light, but in reality we just see
them in their pre-birth state (right after BB). Right ?
No, that's not what he's saying. I don't even think it's meaningful to
compare the rate of time passage at two different times in history.
Such a comparison is only meaningful for two objects that go different
places and come back together. If you carefully define what it means
for two events at different places to be simultaneous, you can also
compare the time rates at the two places, but the answer you get can
depend on the definition of simultaneity chosen.
Mmm. BB theory clearly states that the Universe started out microscopically small.
So all matter / energy in the Universe was once (in) one 'place' and 'time'.
The CMB that we observe now brings us photons back from that 'moment'.
(albeit due to rapid expansion on now make it back to our neck of the woods).
So I think we SHOULD be able to talk about RATE of time passage at two
different times in history....
Special relativity defines distance as it would be measured by rulers
at rest relative to an observer, and time as it would be measured by
clocks at rest relative to an observer. It defines an event near an
observer to be simultaneous with a distant event if the nearby event
occurs halfway between the time light needed to have left the observer
to reach the distant event and the time light from the distant event
arrives.
I needed to draw a picture for that, but I think I understand you
talk about the event horizon here. I understand that.
SR also finds that if the same two events are measured by a second,
moving observer, that they will not seem to be simultaneous.
In cosmology, distance is usually defined as it would be measured by
rulers at rest relative to the expanding universe (i.e. at rest
relative to most galaxies, the average momentum of the cosmic
background radiation, etc.). Time is defined as it would be measured
by clocks at rest relative to the expanding universe. Two events are
defined to be simultaneous if the age of the universe as measured by
such clocks was the same at both events.
Makes sense. But this does not say anything about the RATE of
time in the past. This is what I'm thinking of :
If observers at-rest 7 billion years ago would measure
the age of the universe, would they measure 14-7=7billion years,
or would they maybe measure something much longer ?
Since the density of the Universe was double back then from where it is now,
GR predicts that their time rate must have run slower than ours today.
At least as observed from our point of view.
So we would observe then with a red-shift.
Which, incidentally, happens to look like they are moving away from us...
If this is true, then these old observers would have measured the time
age of the Universe to be longer than 7 billion years.
I am not very strong in GR, but I can imagine that they would
observe the Universe to be anywhere from 7 to 14billion years old.
If this effect is real, even to a certain extend, then it might make the
horizon problem and the age-of-the-universe problem go away completely,
so that there is no need for an inflationary theory...
The definitions of distance, time, and simultaneity are all different.
All of these concepts factor in to the determination of the velocity of
an object.
Special relativity assumes flat space-time. It assumes that lines that
are parallel at one place are parallel along their entire length, and
that non-accelerating objects at rest relative to one another are at
rest relative to each other forever. For down-to-earth purposes, the
first assumption is almost exactly true. The second is nowhere near
true if we use general relativity's definition of proper acceleration,
but it can be made almost exactly true by defining freely falling
objects to be accelerating downward. But over cosmological distances,
both assumptions fail miserably.
The consequence of this is that one must be careful when using special
relativity in cosmology. Does special relativity fail? In general,
yes. But along a narrow path at a specific time, or in a small volume,
the errors introduced are insignificant. One can still compare
velocities of distant objects using the special relativistic
definitions, but the answer you get depends on the path between the two
objects on which you apply the assumptions and definitions of special
relativity, and the specific time you are applying them at each point
along the path.
Thus, you can and will get multiple answers from special relativity
when applied to cosmology. However, none of the velocities you can
calculate using its definitions will be greater than the speed of
light.
All laws of physics, including the constants seem not to have changed over time.
So there is no reason to believe that SR and GR all of a sudden would fail.
You are right that we have to be very carefull when applying them to
cosmology, since it gets so confusing in a expanding Universe.
But I tend to believe that if we apply SR and GR correctly that there
would not be a need for a sort of 'out-of-the-blue' theory like the
inflationary theory.
But using the common cosmological definitions of distance, time, and
simultaneity I mentioned, the rate of change on the distance to a
far-away object can exceed the speed of light. The reasons for the
discrepancy between this speed and the object's velocity relative to us
according to special relativity are:
1. By the special relativistic definitions, those rulers at rest
relative to the expanding universe are moving away from us and thus
undergo length contraction. This works to reduce the change of the
distance from us to a far-away object and us as defined by special
relativity.
2. By the special relativistic definitions, the clocks at rest
relative to the expanding universe are moving away from us and thus
undergo time dilation. This can make the time the object was moving,
as defined by special relativity, longer than it is when using the
cosmological definition.
3. It might seem that effect #2 could be circumvented by measuring the
time at our location instead of the moving objects'. But the events
cosmology would define as happening in our present, would, by the
special relativistic definitions, be happening in the future. This
discrepancy increases as objects become more distant. Thus, distant
events that occur a short time apart as calculated using our clocks and
the cosmological definition of simultaneity, occur later and further
apart as measured by our clocks using the special relativistic
definition.
I understand the relativistic effects of matter moving away from us,
but I don't see why we need to explain that/if anything moves faster
than light. Did we observe apparent faster-than-light movement
that can not be explained by SR effects ?
Also, was this related to the theory of inflation ?
I thought inflation happened only in the first 10^23 sec or so after BB,
when the universe was only of grapefruit size, so there are not a
lot of speed measurements we can do...
If you're interested, I would recommend looking over Ned Wright's
tutorial, since he explains a lot of this stuff well in simple terms,
and he has some good illustrations, which are worth much more than a
thousand words. The tutorial website is here:
http://www.astro.ucla.edu/~wright/cosmo_01.htm
You should especially look at the diagram in part 2, where he shows how
a space-time diagram of a nearly empty expanding universe using special
relativistic coordinates differs from the previous diagram using
cosmological coordinates:
http://www.astro.ucla.edu/~wright/cosmo_02.htm#DH
This illustrates what's going on pretty well, and does so much better
than I could ever try to do with words.
It's a good tutotial. Thanks for the link !
I do not understand the horizon problem that was presented though.
Seems to me there is some strange assumption there that something
must be outside of the horizon, but I don't get why that assumption
had to be made. I'll read it again.
.
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| User: "glbrad01" |
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| Title: Re: Inflationary Theory ; I'm confused |
27 Jan 2005 06:06:25 AM |
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I have to shake my head. 15 billion (to infinity) times 9.8 trillion
kilometers of space to (per) 15 billion (to infinity) years of time equals a
specified magnitude of 300,000 kilometers of space constant to (per) one
second of time constant, just as the equivalent spatial unit length to (per)
a trillionth of a trillionth of a trillionth of a trillionth of a trillionth
of a trillionth of a trillionth of a trillionth of a trillionth....(to
infinity "of a trillionth") of one second of time also, and still, and
always, equals a specified magnitude of 300,000 kilometers of space constant
to (per) one second of time constant.
300,000 kilometers of space constant to (constant per) one second of time
constant (macro-Universe) = 300,000 kilometers of space constant to
(constant per) one second of time constant (micro-universe).
300,000 kps = 300,000 kps
1 second = 1 second
1c = 1c
Velocity x = velocity x
Acceleration y = acceleration y
Motion z = motion z
Cosmological constant zero (instantaneous moment) = cosmological constant
zero (instantaneous moment) (Universal Real Time zero (instantaneous moment)
= universal real time zero (instantaneous moment)).
Frame = frame.
Only the elastically subjective term "relative to the observer" causes the
plural effect 'magnitudes' (objective shattering of "1c" into infinities of
'magnitudes' of 1c). "Tunnel vision's elasticity" is a real but strictly
compartmented physic. Any traveler in motion, as such, whatever his velocity
or acceleration in velocity is will have its magnitude reset to match a
matching magnitude of 1c, both as to the spatial unit length (1) and as to
the unit length of time (1) (1:1).
There is no such as observing space. "Space" is the very essence of
"simultaneously existing", parallelism, parallel sequential, or parallel
universe. So you will observe an extending ruler of light-time frame event
histories, the light physic itself, and magnitudes going away of 1c in "the
light physic itself." These are all you will ever physically observe as
physical observers. All told, a seamless "space-time continuum" VIRTUALITY
of space and time. Never the real things.
The above is strictly an expression of my point of view of one or more of
the realities of the Universe as I see them to be the realities (a point of
view strictly relative to this observer). Any similarities to other modeling
is either intentional or coincidental. Any dis-similarity is
hyper-intentional.
Brad
"I make many mistakes" (butler in The Big Sleep).
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| User: "George Dishman" |
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| Title: Re: Inflationary Theory ; I'm confused |
28 Jan 2005 04:19:10 PM |
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<Groups reduced>
"Rob Dekker" <rob@verific.com> wrote in message
news:7u0Kd.16248$5R.10745@newssvr21.news.prodigy.com...
<snip>
Mmm. BB theory clearly states that the Universe started out
microscopically small.
So all matter / energy in the Universe was once (in) one 'place' and
'time'.
It may avoid some confusion if it is made clear that
this refers to the observable universe. That may be
a very small part of the whole, or the whole may be
infinite.
The CMB that we observe now brings us photons back from that 'moment'.
Not quite, the CMBR is from around 300k years after
that moment. As you say later, inflation lasted a
fraction of a second.
(albeit due to rapid expansion on now make it back to our neck of the
woods).
So I think we SHOULD be able to talk about RATE of time passage at two
different times in history....
You cannot talk about the rate of time without measuring
it against another time (if it is to be a rate). Typically
one projects the proper time of an object onto the worldline
of an observing clock to find a coordinate time.
Special relativity defines distance as it would be measured by rulers
at rest relative to an observer, and time as it would be measured by
clocks at rest relative to an observer. It defines an event near an
observer to be simultaneous with a distant event if the nearby event
occurs halfway between the time light needed to have left the observer
to reach the distant event and the time light from the distant event
arrives.
I needed to draw a picture for that, but I think I understand you
talk about the event horizon here. I understand that.
SR also finds that if the same two events are measured by a second,
moving observer, that they will not seem to be simultaneous.
^ Time
|
Tc +
|\
| \
| \
Tb + E
| /
| /
|/
Ta +
|
---> distance
Distant event E occurred at time Tb if Tb=(Tc+Ta)/2 where
Ta is the time light left to reach E and Tc is the time
light from E returned to the observer.
In cosmology, distance is usually defined as it would be measured by
rulers at rest relative to the expanding universe (i.e. at rest
relative to most galaxies, the average momentum of the cosmic
background radiation, etc.). Time is defined as it would be measured
by clocks at rest relative to the expanding universe. Two events are
defined to be simultaneous if the age of the universe as measured by
such clocks was the same at both events.
Makes sense. But this does not say anything about the RATE of
time in the past. This is what I'm thinking of :
If observers at-rest 7 billion years ago would measure
the age of the universe, would they measure 14-7=7billion years,
or would they maybe measure something much longer ?
Since the density of the Universe was double back then from where it is
now,
GR predicts that their time rate must have run slower than ours today.
At least as observed from our point of view.
So we would observe then with a red-shift.
Which, incidentally, happens to look like they are moving away from us...
If this is true, then these old observers would have measured the time
age of the Universe to be longer than 7 billion years.
I am not very strong in GR, but I can imagine that they would
observe the Universe to be anywhere from 7 to 14billion years old.
They would measure it to be 7 billion years because they
consider _us_ to be the ones that are moving. The CMBR for
example that they measure would be at rest to them (other
than proper motion, the same as for us). They would have
the same view as we would have done if we had been here
7 billion years ago.
Look at this diagram from Ned' tutorial:
http://www.astro.ucla.edu/~wright/cosmo_03.htm#MSTD
Note that the lines with the light cones are not parallel.
Think of a clock as something that marks off equally
spaced 'ticks' along the lines. Project the ticks on one
line onto the next and they will not match the ticks on
that line. This is what the difference in 'rates' means,
it is only an effect from the projection.
<big snip>
It's a good tutotial. Thanks for the link !
I do not understand the horizon problem that was presented though.
Seems to me there is some strange assumption there that something
must be outside of the horizon, but I don't get why that assumption
had to be made. I'll read it again.
The horizon is simply how far we can see within the
universe and is produced by the age. What is outside
is just the continuation of what is inside, but so
far away the light from it hasn't reached us yet.
George
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| User: "Franz Heymann" |
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| Title: Re: Inflationary Theory ; I'm confused |
27 Jan 2005 02:46:39 PM |
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"Rob Dekker" <rob@verific.com> wrote in message
news:7u0Kd.16248$5R.10745@newssvr21.news.prodigy.com...
[snip]
"Jim Black" <ghytrfvbnmju7654@mail.com> wrote in message
news:1106183059.902285.122470@c13g2000cwb.googlegroups.com...
[...]
Special relativity defines distance as it would be measured by
rulers
at rest relative to an observer, and time as it would be measured
by
clocks at rest relative to an observer. It defines an event near
an
observer to be simultaneous with a distant event if the nearby
event
occurs halfway between the time light needed to have left the
observer
to reach the distant event and the time light from the distant
event
arrives.
I needed to draw a picture for that, but I think I understand you
talk about the event horizon here.
What a weird understanding you have. He was speaking about Special
Relativity, which is completely unconnected with concepts like event
horizons.
[snip]
Franz
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| User: "Rob Dekker" |
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| Title: Re: Inflationary Theory ; I'm confused |
27 Jan 2005 06:26:56 PM |
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"Franz Heymann" <notfranz.heymann@btopenworld.com> wrote in message news:ctbjvf$ri3$8@hercules.btinternet.com...
[....]
I needed to draw a picture for that, but I think I understand you
talk about the event horizon here.
What a weird understanding you have. He was speaking about Special
Relativity, which is completely unconnected with concepts like event
horizons.
Sorry.
Event horizon was not the word I was looking for.
I do understood the definition of simultaneous events across distance
that he explained though.
[snip]
Franz
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| User: "Franz Heymann" |
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| Title: Re: Inflationary Theory ; I'm confused |
29 Jan 2005 05:39:55 AM |
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"Rob Dekker" <rob@verific.com> wrote in message
news:kFfKd.16849$5R.3443@newssvr21.news.prodigy.com...
"Franz Heymann" <notfranz.heymann@btopenworld.com> wrote in message
news:ctbjvf$ri3$8@hercules.btinternet.com...
[....]
I needed to draw a picture for that, but I think I understand
you
talk about the event horizon here.
What a weird understanding you have. He was speaking about
Special
Relativity, which is completely unconnected with concepts like
event
horizons.
Sorry.
Event horizon was not the word I was looking for.
I do understood the definition of simultaneous events across
distance
that he explained though.
It is possible that you were talking about the light cone.
Franz
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| User: "Rob Dekker" |
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| Title: Re: Inflationary Theory ; I'm confused |
30 Jan 2005 10:17:39 PM |
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"Franz Heymann" <notfranz.heymann@btopenworld.com> wrote in message news:ctfsma$pk$1@hercules.btinternet.com...
[...]
Sorry.
Event horizon was not the word I was looking for.
I do understood the definition of simultaneous events across
distance
that he explained though.
It is possible that you were talking about the light cone.
Thank you.
Franz
.
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| User: "Joseph Lazio" |
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| Title: Re: Inflationary Theory ; I'm confused |
30 Jan 2005 07:07:28 AM |
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"RD" == Rob Dekker <rob@verific.com> writes:
RD> Mmm. BB theory clearly states that the Universe started out
RD> microscopically small. So all matter / energy in the Universe was
RD> once (in) one 'place' and 'time'.
No, it doesn't. This is a problem with common descriptions of the BB
model. The *observable* Universe became quite small in the past,
because the observable Universe is defined by the (speed of light) x
(age of the Universe).
The Universe as a whole could be (and probably is) much larger than
the observable Universe.
[...]
RD> I do not understand the horizon problem that was presented though.
RD> Seems to me there is some strange assumption there that something
RD> must be outside of the horizon, but I don't get why that
RD> assumption had to be made.
See above.
--
Lt. Lazio, HTML police | e-mail:
No means no, stop rape. | http://patriot.net/%7Ejlazio/
sci.astro FAQ at http://sciastro.astronomy.net/sci.astro.html
.
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| User: "Rob Dekker" |
|
| Title: Re: Inflationary Theory ; I'm confused |
30 Jan 2005 10:36:43 PM |
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|
"Joseph Lazio" <jlazio@adams.patriot.net> wrote in message news:llwttvawvj.fsf@adams.patriot.net...
"RD" == Rob Dekker <rob@verific.com> writes:
RD> Mmm. BB theory clearly states that the Universe started out
RD> microscopically small. So all matter / energy in the Universe was
RD> once (in) one 'place' and 'time'.
No, it doesn't. This is a problem with common descriptions of the BB
model. The *observable* Universe became quite small in the past,
because the observable Universe is defined by the (speed of light) x
(age of the Universe).
I understand that.
The Universe as a whole could be (and probably is) much larger than
the observable Universe.
OK. And I understand that this effect (the Universe as a whole must be
larger than the observable Universe) is in fact a requirement if
inflationary theory is correct. Right ?
[...]
RD> I do not understand the horizon problem that was presented though.
RD> Seems to me there is some strange assumption there that something
RD> must be outside of the horizon, but I don't get why that
RD> assumption had to be made.
See above.
This is at the core of my 'confusion' : I don't understand why inflationary
theory would be needed. I don't see that the horizon problem (at the root
of inflationary theory) is so hard to overcome with existing theories of BB
and with proper application of GR.
I keep on imagining the Universe as a 4-dimensional space sphere, who's
circumfence grows (at its 3-dim surface) with with speed of light.
Looking deep into space means deep into the past, means looking along
a curve back to the center of the sphere (where the BB happened).
Our light cone back to the past would be a pear-shape back to the center.
Similar to the pear shape in Wright's tutorial :
http://www.astro.ucla.edu/~wright/cosmo_03.htm
with the difference that the positive and negative side of the x-axis would
fold 90degrees to the south and touch each other, to complete the sphere.
I don't see why there would be a need for a FTL space explosion as
proposed with inflationary theory in this simple model.
--
Lt. Lazio, HTML police | e-mail:
No means no, stop rape. | http://patriot.net/%7Ejlazio/
sci.astro FAQ at http://sciastro.astronomy.net/sci.astro.html
.
|
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| User: "Joseph Lazio" |
|
| Title: Re: Inflationary Theory ; I'm confused |
01 Feb 2005 07:53:10 AM |
|
|
"RD" == Rob Dekker <rob@verific.com> writes:
RD> "Joseph Lazio" <jlazio@adams.patriot.net> wrote in message
RD> news:llwttvawvj.fsf@adams.patriot.net...
RD> Mmm. BB theory clearly states that the Universe started out
RD> microscopically small. So all matter / energy in the Universe was
RD> once (in) one 'place' and 'time'.
No, it doesn't. [...] The *observable* Universe became quite
small in the past, because the observable Universe is defined by
the (speed of light) x (age of the Universe).
RD> I understand that.
The Universe as a whole could be (and probably is) much larger than
the observable Universe.
RD> OK. And I understand that this effect (the Universe as a whole
RD> must be larger than the observable Universe) is in fact a
RD> requirement if inflationary theory is correct. Right ?
[...]
RD> I do not understand the horizon problem that was presented though.
RD> Seems to me there is some strange assumption there that something
RD> must be outside of the horizon, but I don't get why that
RD> assumption had to be made.
See above.
RD> This is at the core of my 'confusion' : I don't understand why
RD> inflationary theory would be needed. I don't see that the horizon
RD> problem (...) is so hard to overcome with existing theories of BB
RD> and with proper application of GR.
Take two points on opposite sides of the sky. To very high precision,
the intensity of the cosmic microwave background that we measure from
both points is very nearly the same. At the time when the CMB formed,
about 300,000 years after the Big Bang, they were outside each other's
horizon. In other words, the size of the horizon or the size of the
observable Universe for an observer at each of these two points did
*not* include the observer at the other point. Therefore they should
know nothing about each other, and there is no reason to expect the
CMB from one direction to have the same intensity as the CMB from
another direction. Yet it does.
--
Lt. Lazio, HTML police | e-mail:
No means no, stop rape. | http://patriot.net/%7Ejlazio/
sci.astro FAQ at http://sciastro.astronomy.net/sci.astro.html
.
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| User: "Rob Dekker" |
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| Title: Re: Inflationary Theory ; I'm confused |
01 Feb 2005 09:28:46 PM |
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Thanks for your explanation Joseph.
A few comments and questions below.
"Joseph Lazio" <jlazio@adams.patriot.net> wrote in message news:lllla8gzeh.fsf@adams.patriot.net...
[...]
RD> This is at the core of my 'confusion' : I don't understand why
RD> inflationary theory would be needed. I don't see that the horizon
RD> problem (...) is so hard to overcome with existing theories of BB
RD> and with proper application of GR.
Take two points on opposite sides of the sky. To very high precision,
the intensity of the cosmic microwave background that we measure from
both points is very nearly the same. At the time when the CMB formed,
about 300,000 years after the Big Bang, they were outside each other's
horizon.
Mmm. I'm not sure if that is really true.
The Universe was only 300,000 years old, and if it was/is round
(a 4-dim sphere) and expanding at light speed, then the two points
might have been very close to each other at that time at the far-side
of the sphere.... Just draw the horizon on polar paper back to the center.
How can we even know how far apart they were, and if they
did or did not share an event history ?
At that time, if the Universe was only 300,000 LYs in size, any
point on that sphere has a light cone back into time, and back into
an even smaller sphere.
So can it not be that all light cones / horizons always just touch
each other at the beginning of time/space, rather than to conclude
up-front that there must be something 'unseen' ?
In other words, the size of the horizon or the size of the
observable Universe for an observer at each of these two points did
*not* include the observer at the other point. Therefore they should
know nothing about each other, and there is no reason to expect the
CMB from one direction to have the same intensity as the CMB from
another direction. Yet it does.
As far as the isotropy is concerned, a Universe of only 300,000
years old must have been tens of thousands of degrees hot and
very dense. It should not be so surprising that the temperature
and matter distribution was still very consistent.
It still (pretty consistent) on our side of the Universe 15 billion years later...
--
Lt. Lazio, HTML police | e-mail:
No means no, stop rape. | http://patriot.net/%7Ejlazio/
sci.astro FAQ at http://sciastro.astronomy.net/sci.astro.html
.
|
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| User: "Joseph Lazio" |
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| Title: Re: Inflationary Theory ; I'm confused |
11 Feb 2005 01:59:18 PM |
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"RD" == Rob Dekker <rob@verific.com> writes:
RD> "Joseph Lazio" <jlazio@adams.patriot.net> wrote in message
RD> news:lllla8gzeh.fsf@adams.patriot.net...
RD> [...] This is at the core of my 'confusion' : I don't understand
RD> why inflationary theory would be needed. I don't see that the
RD> horizon problem (...) is so hard to overcome with existing
RD> theories of BB and with proper application of GR.
Take two points on opposite sides of the sky. To very high
precision, the intensity of the cosmic microwave background that we
measure from both points is very nearly the same. At the time when
the CMB formed, about 300,000 years after the Big Bang, they were
outside each other's horizon.
RD> Mmm. I'm not sure if that is really true. The Universe was only
RD> 300,000 years old, and if it was/is round (a 4-dim sphere) and
RD> expanding at light speed, then the two points might have been very
RD> close to each other at that time at the far-side of the
RD> sphere.... Just draw the horizon on polar paper back to the
RD> center.
There may be some specific geometries that would allow you to avoid
the horizon problem. As a general issue, though, if one takes two
widely separated points, their light cones do not intersect at the
time when the CMB formed.
In other words, the size of the horizon or the size of the
observable Universe for an observer at each of these two points did
*not* include the observer at the other point. Therefore they
should know nothing about each other, and there is no reason to
expect the CMB from one direction to have the same intensity as the
CMB from another direction. Yet it does.
RD> As far as the isotropy is concerned, a Universe of only 300,000
RD> years old must have been tens of thousands of degrees hot and very
RD> dense. It should not be so surprising that the temperature and
RD> matter distribution was still very consistent. It still (pretty
RD> consistent) on our side of the Universe 15 billion years later...
Actually, at the time of the formation of the CMB, the temperature of
the Universe was only about 3000 K, IIRC. The temperature really
doesn't matter, though, from the standpoint of the horizon problem.
In general, two points will have the same temperature only if light
can travel between them. Only if the entire Universe were only
300,000 light years across at the time of the CMB formation should the
temperature be the same.
--
Lt. Lazio, HTML police | e-mail:
No means no, stop rape. | http://patriot.net/%7Ejlazio/
sci.astro FAQ at http://sciastro.astronomy.net/sci.astro.html
.
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| User: "Aidan Karley" |
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| Title: Re: Inflationary Theory ; I'm confused |
11 Feb 2005 07:00:08 PM |
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In article <lly8duzx49.fsf@adams.patriot.net>, Joseph Lazio wrote:
In general, two points will have the same temperature only if light
can travel between them.
What? I can only warm my arse against a fire if my arse is as hot
as the fire? Pass the jalapeno beans! [Eyes water]
Only if the entire Universe were only
300,000 light years across at the time of the CMB formation should the
temperature be the same.
Errr, so by night my skin is the 6kK approx of the Sun's surface,
and by night I freeze to Olber's paradox (or glow a medium yellow,
depends on your understanding of Olber's P.)
--
Aidan Karley,
Aberdeen, Scotland,
Location: 57°10'11" N, 02°08'43" W (sub-tropical Aberdeen), 0.021233
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| User: "" |
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| Title: Re: Inflationary Theory ; I'm confused |
31 Jan 2005 12:28:05 AM |
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Rob Dekker wrote:
"Joseph Lazio" <jlazio@adams.patriot.net> wrote in message
news:llwttvawvj.fsf@adams.patriot.net...
"RD" == Rob Dekker <rob@verific.com> writes:
RD> Mmm. BB theory clearly states that the Universe started out
RD> microscopically small. So all matter / energy in the Universe
was
RD> once (in) one 'place' and 'time'.
No, it doesn't. This is a problem with common descriptions of the
BB
model. The *observable* Universe became quite small in the past,
because the observable Universe is defined by the (speed of light)
x
(age of the Universe).
I understand that.
The Universe as a whole could be (and probably is) much larger than
the observable Universe.
OK. And I understand that this effect (the Universe as a whole must
be
larger than the observable Universe) is in fact a requirement if
inflationary theory is correct. Right ?
[...]
RD> I do not understand the horizon problem that was presented
though.
RD> Seems to me there is some strange assumption there that
something
RD> must be outside of the horizon, but I don't get why that
RD> assumption had to be made.
See above.
This is at the core of my 'confusion' : I don't understand why
inflationary
theory would be needed. I don't see that the horizon problem (at the
root
of inflationary theory) is so hard to overcome with existing theories
of BB
and with proper application of GR.
I keep on imagining the Universe as a 4-dimensional space sphere,
who's
circumfence grows (at its 3-dim surface) with with speed of light.
Looking deep into space means deep into the past, means looking along
a curve back to the center of the sphere (where the BB happened).
Our light cone back to the past would be a pear-shape back to the
center.
Similar to the pear shape in Wright's tutorial :
http://www.astro.ucla.edu/~wright/cosmo_03.htm
with the difference that the positive and negative side of the x-axis
would
fold 90degrees to the south and touch each other, to complete the
sphere.
I don't see why there would be a need for a FTL space explosion as
proposed with inflationary theory in this simple model.
Remember optics? If light comes to your eye along a curve, WHERE does
the object (image) APPEAR to be? (Hint: Not up your bum; you may see
such an image, but have a pretty good idea that it is not where it
appears)
Consider the milky way (in 2 dimension here for simplicity) taking
100my to revolve. Say we are at A, and observing an object which is
past (in line with) O (center of galaxy).
If the distant object (B) is at 500mly, where IS IT according to our
A,O line?????????
Now consider another star(C) which appears to be in line with A,O,B,C
but which is at 975mly- where is/was it?????????
Get it? Things at different distances are in different directions due
to INFORMATION DELAY, but do not SEEM to be. And this is not even
allowing for natural transverse motion of the bodies ref us; the things
could be anywhere.
Sorry about the cosmological maps being pretty useless- they look
pretty.
Jim G
c'=c+v
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| User: "" |
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| Title: Re: Inflationary Theory ; I'm confused |
27 Jan 2005 03:06:21 AM |
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Rob Dekker wrote:
I do not understand the horizon problem that was presented though.
Seems to me there is some strange assumption there that something
must be outside of the horizon, but I don't get why that assumption
had to be made. I'll read it again.
These days "enlightened" Bigbangers claim that "all places are
equally the center of the universe". So it must follow that an observer
at what we perceive to be the horizon
must see an equal distance beyond, and back to us, for him to be at his
center.
Jim G
c'=c+v
.
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| User: "Franz Heymann" |
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| Title: Re: Inflationary Theory ; I'm confused |
27 Jan 2005 02:46:40 PM |
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"jgreenfield@seol.net.au" <jgreen@seol.net.au> wrote in message
news:1106816781.925489.16400@z14g2000cwz.googlegroups.com...
Rob Dekker wrote:
I do not understand the horizon problem that was presented though.
Seems to me there is some strange assumption there that something
must be outside of the horizon, but I don't get why that
assumption
had to be made. I'll read it again.
These days "enlightened" Bigbangers claim that "all places are
equally the center of the universe". So it must follow that an
observer
at what we perceive to be the horizon
must see an equal distance beyond, and back to us, for him to be at
his
Of course. If you start walking in any direction on the surface of
the earth, the horizon will always stay ahead of you. There is
nowhere where you are in any danger of meeting an edge and falling
off.
Franz
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| User: "Dirk Van de moortel" |
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| Title: Re: Inflationary Theory ; I'm confused |
27 Jan 2005 04:54:52 AM |
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"jgreenfield@seol.net.au" <jgreen@seol.net.au> wrote in message news:1106816781.925489.16400@z14g2000cwz.googlegroups.com...
Rob Dekker wrote:
I do not understand the horizon problem that was presented though.
Seems to me there is some strange assumption there that something
must be outside of the horizon, but I don't get why that assumption
had to be made. I'll read it again.
These days "enlightened" Bigbangers claim that "all places are
equally the center of the universe". So it must follow that an observer
at what we perceive to be the horizon
must see an equal distance beyond, and back to us, for him to be at his
center.
These days "enlightened" people claim that "all places are
equally the center of the surface of the Earth". So it must
follow that an observer at what we perceive to be the
horizon must see an equal distance beyond, and back to
us, for him to be at his center.
Dirk Vdm
.
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| User: "" |
|
| Title: Re: Inflationary Theory ; I'm confused |
27 Jan 2005 05:17:47 PM |
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Dirk Van de moortel wrote:
"jgreenfield@seol.net.au" <jgreen@seol.net.au> wrote in message
news:1106816781.925489.16400@z14g2000cwz.googlegroups.com...
Rob Dekker wrote:
I do not understand the horizon problem that was presented
though.
Seems to me there is some strange assumption there that something
must be outside of the horizon, but I don't get why that
assumption
had to be made. I'll read it again.
These days "enlightened" Bigbangers claim that "all places are
equally the center of the universe". So it must follow that an
observer
at what we perceive to be the horizon
must see an equal distance beyond, and back to us, for him to be at
his
center.
These days "enlightened" people claim that "all places are
equally the center of the surface of the Earth". So it must
follow that an observer at what we perceive to be the
horizon must see an equal distance beyond, and back to
us, for him to be at his center.
Dirk Vdm
I forgot you were so archaic.
News flash for Dirk: "Sun does not circle the earth- the fact that the
earth has a curved surface has NOTHING to do with properties of space,
time, and the real geometry in which the shortest distance between two
points is a STRAIGHT line".
If you wish to test this statement, ask those who regularly measure the
distance to the moon (an object NOT on the earth's surface), and ask
them whether the radar beam follows a curve, and how many degrees of
arc are allowed for in the calculation for DIRECT earth/moon
separation.
Jim G
c'=c+v
.
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| User: "Franz Heymann" |
|
| Title: Re: Inflationary Theory ; I'm confused |
29 Jan 2005 05:29:27 AM |
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<jgreen@seol.net.au> wrote in message
news:1106867867.682753.51320@z14g2000cwz.googlegroups.com...
Dirk Van de moortel wrote:
"jgreenfield@seol.net.au" <jgreen@seol.net.au> wrote in message
news:1106816781.925489.16400@z14g2000cwz.googlegroups.com...
Rob Dekker wrote:
I do not understand the horizon problem that was presented
though.
Seems to me there is some strange assumption there that
something
must be outside of the horizon, but I don't get why that
assumption
had to be made. I'll read it again.
These days "enlightened" Bigbangers claim that "all places are
equally the center of the universe". So it must follow that an
observer
at what we perceive to be the horizon
must see an equal distance beyond, and back to us, for him to be
at
his
center.
These days "enlightened" people claim that "all places are
equally the center of the surface of the Earth". So it must
follow that an observer at what we perceive to be the
horizon must see an equal distance beyond, and back to
us, for him to be at his center.
Dirk Vdm
I forgot you were so archaic.
News flash for Dirk: "Sun does not circle the earth- the fact that
the
earth has a curved surface has NOTHING to do with properties of
space,
time, and the real geometry in which the shortest distance between
two
points is a STRAIGHT line".
If you wish to test this statement, ask those who regularly measure
the
distance to the moon (an object NOT on the earth's surface), and ask
them whether the radar beam follows a curve, and how many degrees of
arc are allowed for in the calculation for DIRECT earth/moon
separation.
Quit uttering the kind of horseshit exemplified by the stuff I leave
unsnipped above here.
Just admit that your neurons are not geared to get to grips with the
topics in which you attempt to discuss.
Franz
.
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| User: "Dirk Van de moortel" |
|
| Title: Re: Inflationary Theory ; I'm confused |
28 Jan 2005 04:35:48 AM |
|
|
<jgreen@seol.net.au> wrote in message news:1106867867.682753.51320@z14g2000cwz.googlegroups.com...
Dirk Van de moortel wrote:
"jgreenfield@seol.net.au" <jgreen@seol.net.au> wrote in message
news:1106816781.925489.16400@z14g2000cwz.googlegroups.com...
Rob Dekker wrote:
I do not understand the horizon problem that was presented
though.
Seems to me there is some strange assumption there that something
must be outside of the horizon, but I don't get why that
assumption
had to be made. I'll read it again.
These days "enlightened" Bigbangers claim that "all places are
equally the center of the universe". So it must follow that an
observer
at what we perceive to be the horizon
must see an equal distance beyond, and back to us, for him to be at
his
center.
These days "enlightened" people claim that "all places are
equally the center of the surface of the Earth". So it must
follow that an observer at what we perceive to be the
horizon must see an equal distance beyond, and back to
us, for him to be at his center.
Dirk Vdm
I forgot you were so archaic.
That's okay. I forgot you were so stupid:
http://users.pandora.be/vdmoortel/dirk/Physics/Fumbles/CoverUp.html
http://users.pandora.be/vdmoortel/dirk/Physics/Fumbles/GDefence.html
http://users.pandora.be/vdmoortel/dirk/Physics/Fumbles/OneDim.html
http://users.pandora.be/vdmoortel/dirk/Physics/Fumbles/Gullible.html
http://users.pandora.be/vdmoortel/dirk/Physics/Fumbles/RelativityCancer.html
Dirk Vdm
.
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| User: "" |
|
| Title: Re: Inflationary Theory ; I'm confused |
28 Jan 2005 11:53:28 PM |
|
|
Dirk Van de moortel wrote:
<jgreen@seol.net.au> wrote in message
news:1106867867.682753.51320@z14g2000cwz.googlegroups.com...
Dirk Van de moortel wrote:
"jgreenfield@seol.net.au" <jgreen@seol.net.au> wrote in message
news:1106816781.925489.16400@z14g2000cwz.googlegroups.com...
Rob Dekker wrote:
I do not understand the horizon problem that was presented
though.
Seems to me there is some strange assumption there that
something
must be outside of the horizon, but I don't get why that
assumption
had to be made. I'll read it again.
These days "enlightened" Bigbangers claim that "all places are
equally the center of the universe". So it must follow that an
observer
at what we perceive to be the horizon
must see an equal distance beyond, and back to us, for him to
be at
his
center.
These days "enlightened" people claim that "all places are
equally the center of the surface of the Earth". So it must
follow that an observer at what we perceive to be the
horizon must see an equal distance beyond, and back to
us, for him to be at his center.
Dirk Vdm
I forgot you were so archaic.
That's okay. I forgot you were so stupid:
http://users.pandora.be/vdmoortel/dirk/Physics/Fumbles/CoverUp.html
http://users.pandora.be/vdmoortel/dirk/Physics/Fumbles/GDefence.html
http://users.pandora.be/vdmoortel/dirk/Physics/Fumbles/OneDim.html
http://users.pandora.be/vdmoortel/dirk/Physics/Fumbles/Gullible.html
http://users.pandora.be/vdmoortel/dirk/Physics/Fumbles/RelativityCancer.html
Dirk Vdm
Par for the DV course!
Faced with an implacable contradiction, in this case ONE observer
getting TWO
results from clocks timing the SAME event (orbit of the sun), the ONLY
response
he is capable of is a demonstration of his "cut and paste" skills-
typical!!!!!
Jim G
c'=c+v
.
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| User: "Franz Heymann" |
|
| Title: Re: Inflationary Theory ; I'm confused |
29 Jan 2005 05:38:11 AM |
|
|
"jgreenfield@seol.net.au" <jgreen@seol.net.au> wrote in message
news:1106978007.994399.112000@c13g2000cwb.googlegroups.com...
Dirk Van de moortel wrote:
<jgreen@seol.net.au> wrote in message
news:1106867867.682753.51320@z14g2000cwz.googlegroups.com...
Dirk Van de moortel wrote:
"jgreenfield@seol.net.au" <jgreen@seol.net.au> wrote in
message
news:1106816781.925489.16400@z14g2000cwz.googlegroups.com...
Rob Dekker wrote:
I do not understand the horizon problem that was presented
though.
Seems to me there is some strange assumption there that
something
must be outside of the horizon, but I don't get why that
assumption
had to be made. I'll read it again.
These days "enlightened" Bigbangers claim that "all places
are
equally the center of the universe". So it must follow that
an
observer
at what we perceive to be the horizon
must see an equal distance beyond, and back to us, for him
to
be at
his
center.
These days "enlightened" people claim that "all places are
equally the center of the surface of the Earth". So it must
follow that an observer at what we perceive to be the
horizon must see an equal distance beyond, and back to
us, for him to be at his center.
Dirk Vdm
I forgot you were so archaic.
That's okay. I forgot you were so stupid:
http://users.pandora.be/vdmoortel/dirk/Physics/Fumbles/CoverUp.html
http://users.pandora.be/vdmoortel/dirk/Physics/Fumbles/GDefence.html
http://users.pandora.be/vdmoortel/dirk/Physics/Fumbles/OneDim.html
http://users.pandora.be/vdmoortel/dirk/Physics/Fumbles/Gullible.html
http://users.pandora.be/vdmoortel/dirk/Physics/Fumbles/RelativityCancer.html
Dirk Vdm
Par for the DV course!
Faced with an implacable contradiction, in this case ONE observer
getting TWO
results from clocks timing the SAME event (orbit of the sun), the
ONLY
response
he is capable of is a demonstration of his "cut and paste" skills-
typical!!!!!
Balls.
I have used objects whose mean life times have been increased by
factors of up to 1,400 (one thousand four hundred) times beyond that
of their stationary counterparts.
We are not talking of little corrections here and there, but *factors*
in excess of 1000.
Franz
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| User: "" |
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| Title: Re: Inflationary Theory ; I'm confused |
19 Jan 2005 09:01:37 PM |
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Jim Black wrote:
If you're interested, I would recommend looking over Ned Wright's
tutorial, since he explains a lot of this stuff well in simple terms,
and he has some good illustrations, which are worth much more than a
thousand words. The tutorial website is here:
http://www.astro.ucla.edu/~wright/cosmo_01.htm
......and the cosmological pictures which bury SR are those which show
material streams (sic trains) which have been measured to be travelling
at 98%c, and which ARE NOT contracted. Those who think that looking
ALONG the path of that material ACTUALLY shortens it, are victims of
ILLUSION, and should apply their intelligence into understanding that
distance and time are invariant. Don't become another deluded victim of
information transfer delay!
Jim G
c'=c+v
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| User: "Franz Heymann" |
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| Title: Re: Inflationary Theory ; I'm confused |
26 Jan 2005 10:23:35 AM |
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<jgreen@seol.net.au> wrote in message
news:1106190097.877421.278430@c13g2000cwb.googlegroups.com...
Jim Black wrote:
If you're interested, I would recommend looking over Ned Wright's
tutorial, since he explains a lot of this stuff well in simple
terms,
and he has some good illustrations, which are worth much more than
a
thousand words. The tutorial website is here:
http://www.astro.ucla.edu/~wright/cosmo_01.htm
.....and the cosmological pictures which bury SR are those which
show
material streams (sic trains) which have been measured to be
travelling
at 98%c, and which ARE NOT contracted.
How do you know they are not foreshortened?
In what direction does this motion take place?
Those who think that looking
ALONG the path of that material ACTUALLY shortens it, are victims of
ILLUSION, and should apply their intelligence into understanding
that
distance and time are invariant. Don't become another deluded victim
of
information transfer delay!
You are drivelling.
Now let me tell you of a real observation of relativistic
foreshortening:
The electric field of a stationary electron is spherically
symmetrical.
According to SR the field lines of a moving electron become
foreshortened in such a way that almost all the field lies in a
directon transverse to the direction of motion. The field lines so to
speak gt squashed flat, so that at speeds of, say, 99.99% of that of
light, which are dead easy to obtain in a high energy lab., the field
lines in fact look flatter than the spokes of a bicycle wheel. The
reality of this has beem proved as follows:
There is a calculation, called the Weiszacker-Williams approximation,
which says that these field lines are all so nearly transverse to the
direction of motion of the electron, and they move so nearly with the
speed of light, that they will behave very nearly like a collection of
photons. On this basis they calculated how these "photons" would be
deflected by a Compton scattering process as they interacted with the
charge of a nearby nucleus. They ended with a formula for the
production cross section for Bremsstrahlung.
The calculated value and the experimental values agreed for all the
nucleii and all the electron energies for which data was available.
Needless to say, if this foreshortening is not taken into account, the
predictions turn out to be crap.
Franz
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| User: "Rob Dekker" |
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| Title: Re: Inflationary Theory ; I'm confused |
19 Jan 2005 11:29:39 PM |
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Jim,
Thanks for a great writeup !!
This makes a lot of sense, and I am reading the tutorial as-we-speak.
In the back of my mind, I still have this idea that the early Universe
contained much more energy per volume unit than today; so
relativistic effects should be considered on top of the 'low-density'
space-time diagram. Essentially all early matter should be in a deep gravity well
(because the density was so much higher). And in a deep gravity well
time moves much slower than outside. Somehow I feel that that effect
might the 'inflation' theory of BB. So inflation theory would not have to be
postulated 'out-of-the-blue', but could be explained with relativistic
effects in early dense and expanding Universe..
But I need to first read-up on basic cosmology before I should dig into the
why and how of inflation theory.
Thanks again for the great links and your clear explanations.
Rob
"Jim Black" <ghytrfvbnmju7654@mail.com> wrote in message news:1106183059.902285.122470@c13g2000cwb.googlegroups.com...
Rob Dekker wrote:
"Sam Wormley" <swormley1@mchsi.com> wrote in message
news:zaaHd.12720$EG1.5271@attbi_s53...
Rob Dekker wrote:
I am confused about this inflationary period.
I've read somewhere that the Universe expanded to
a size of 40 million light years within a miniscule time.
This would clearly violate the limitation of the speed
of light.
Can objects move away from us faster than the speed of light?
http://www.astro.ucla.edu/~wright/cosmology_faq.html#FTL
I think you are saying that since the time ran much slower in the
very early Universe than it does now, that therefor objects seem
to move away from us faster than light, but in reality we just see
them in their pre-birth state (right after BB). Right ?
No, that's not what he's saying. I don't even think it's meaningful to
compare the rate of time passage at two different times in history.
Such a comparison is only meaningful for two objects that go different
places and come back together. If you carefully define what it means
for two events at different places to be simultaneous, you can also
compare the time rates at the two places, but the answer you get can
depend on the definition of simultaneity chosen.
Special relativity defines distance as it would be measured by rulers
at rest relative to an observer, and time as it would be measured by
clocks at rest relative to an observer. It defines an event near an
observer to be simultaneous with a distant event if the nearby event
occurs halfway between the time light needed to have left the observer
to reach the distant event and the time light from the distant event
arrives.
In cosmology, distance is usually defined as it would be measured by
rulers at rest relative to the expanding universe (i.e. at rest
relative to most galaxies, the average momentum of the cosmic
background radiation, etc.). Time is defined as it would be measured
by clocks at rest relative to the expanding universe. Two events are
defined to be simultaneous if the age of the universe as measured by
such clocks was the same at both events.
The definitions of distance, time, and simultaneity are all different.
All of these concepts factor in to the determination of the velocity of
an object.
Special relativity assumes flat space-time. It assumes that lines that
are parallel at one place are parallel along their entire length, and
that non-accelerating objects at rest relative to one another are at
rest relative to each other forever. For down-to-earth purposes, the
first assumption is almost exactly true. The second is nowhere near
true if we use general relativity's definition of proper acceleration,
but it can be made almost exactly true by defining freely falling
objects to be accelerating downward. But over cosmological distances,
both assumptions fail miserably.
The consequence of this is that one must be careful when using special
relativity in cosmology. Does special relativity fail? In general,
yes. But along a narrow path at a specific time, or in a small volume,
the errors introduced are insignificant. One can still compare
velocities of distant objects using the special relativistic
definitions, but the answer you get depends on the path between the two
objects on which you apply the assumptions and definitions of special
relativity, and the specific time you are applying them at each point
along the path.
Thus, you can and will get multiple answers from special relativity
when applied to cosmology. However, none of the velocities you can
calculate using its definitions will be greater than the speed of
light.
But using the common cosmological definitions of distance, time, and
simultaneity I mentioned, the rate of change on the distance to a
far-away object can exceed the speed of light. The reasons for the
discrepancy between this speed and the object's velocity relative to us
according to special relativity are:
1. By the special relativistic definitions, those rulers at rest
relative to the expanding universe are moving away from us and thus
undergo length contraction. This works to reduce the change of the
distance from us to a far-away object and us as defined by special
relativity.
2. By the special relativistic definitions, the clocks at rest
relative to the expanding universe are moving away from us and thus
undergo time dilation. This can make the time the object was moving,
as defined by special relativity, longer than it is when using the
cosmological definition.
3. It might seem that effect #2 could be circumvented by measuring the
time at our location instead of the moving objects'. But the events
cosmology would define as happening in our present, would, by the
special relativistic definitions, be happening in the future. This
discrepancy increases as objects become more distant. Thus, distant
events that occur a short time apart as calculated using our clocks and
the cosmological definition of simultaneity, occur later and further
apart as measured by our clocks using the special relativistic
definition.
If you're interested, I would recommend looking over Ned Wright's
tutorial, since he explains a lot of this stuff well in simple terms,
and he has some good illustrations, which are worth much more than a
thousand words. The tutorial website is here:
http://www.astro.ucla.edu/~wright/cosmo_01.htm
You should especially look at the diagram in part 2, where he shows how
a space-time diagram of a nearly empty expanding universe using special
relativistic coordinates differs from the previous diagram using
cosmological coordinates:
http://www.astro.ucla.edu/~wright/cosmo_02.htm#DH
This illustrates what's going on pretty well, and does so much better
than I could ever try to do with words.
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| User: "" |
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| Title: Re: Inflationary Theory ; I'm confused |
20 Jan 2005 10:02:38 PM |
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Rob Dekker wrote:
And in a deep gravity well
time moves much slower than outside. Somehow I feel that that effect
might the 'inflation' theory of BB. So inflation theory would not
have to be
postulated 'out-of-the-blue', but could be explained with
relativistic
effects in early dense and expanding Universe..
Rob, gravity is different at the earth's center than at the surface.
Have you noticed the core circling the sun at a different velocity than
the surface? For the SAME distance, differently gravitationally
effected matter takes the SAME amount of time to cover the trip. ergo,
as v=d/t gravity has NO EFFECT on time. It only effects the velocity
of matter (and EM particles), and thereby the rate of movement of
information.
The marvellous mish-mash of mathemagics conjured up to support GR and
BB are necessary for supporters to claim "proofs", but 1c+1c=2c , and
the theories are therefore wrong.
Jim G
c'=c+v
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| User: "Franz Heymann" |
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| Title: Re: Inflationary Theory ; I'm confused |
26 Jan 2005 10:23:36 AM |
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<jgreen@seol.net.au> wrote in message
news:1106280158.605904.10230@f14g2000cwb.googlegroups.com...
Rob Dekker wrote:
And in a deep gravity well
time moves much slower than outside. Somehow I feel that that
effect
might the 'inflation' theory of BB. So inflation theory would not
have to be
postulated 'out-of-the-blue', but could be explained with
relativistic
effects in early dense and expanding Universe..
Rob, gravity is different at the earth's center than at the surface.
Have you noticed the core circling the sun at a different velocity
than
the surface?
No.
Have you?
Before answering, do take into account that there is no photon at the
core of the sun which can escape to the surface.
For the SAME distance, differently gravitationally
effected matter takes the SAME amount of time to cover the trip.
ergo,
as v=d/t gravity has NO EFFECT on time.
Please show us your calculation.
It only effects the velocity
of matter (and EM particles), and thereby the rate of movement of
information.
The marvellous mish-mash of mathemagics conjured up to support GR
and
BB are necessary for supporters to claim "proofs", but 1c+1c=2c ,
and
the theories are therefore wrong.
What is this marvellous mish-mash of which you speak?
Please give us a small quantitative selection of that.
Franz
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