Science > Physics > Article: Gamma-ray burst study may rule out cosmological constant
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Science > Physics |
| User: |
"Robert Karl Stonjek" |
| Date: |
11 Jan 2006 02:37:34 PM |
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Article: Gamma-ray burst study may rule out cosmological constant |
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Gamma-ray burst study may rule out cosmological constant
15:15 11 January 2006=20
NewScientist.com news service=20
Maggie McKee, Washington DC
Dark energy - the mysterious force that drives the acceleration of the =
universe - changes over time, controversial new calculations suggest. If =
true, the work rules out Einstein's notion of a "cosmological constant" =
and suggests dark energy, which now repels space, once drew it together.
Astronomers invoked the concept of dark energy to explain supernovae =
observations in the late 1990s that the universe is not only expanding =
but accelerating. The supernovae appeared dimmer - and therefore more =
distant - than expected, given their red shift, which measures how much =
their light has been stretched by the expansion of space.
But it is still not clear what dark energy is. Theories range from a =
"vacuum" energy of space itself which is fixed in value - an idea =
Einstein proposed as the "cosmological constant" - to more exotic =
possibilities, such as quintessence - a type of energy field that can =
vary over space and time.
So far, supernova studies have supported the cosmological constant - one =
recent study of 70 supernovae reported that the strength of repulsion =
given by dark energy could not have changed by more than about 20% over =
the past eight billion years.
Reliable data
But supernovae are too dim to be seen over the largest cosmic distances. =
So some astronomers argue that gamma-ray bursts (GRBs) - violent, =
fleeting explosions that accompany the deaths of some massive stars - =
are better signposts. At about 100 times brighter than supernovae, they =
can be seen at much greater distances.
Now, astronomer Bradley Schaefer of Louisiana State University in Baton =
Rouge, US, has used observations of 52 GRBs to suggest that dark energy =
has changed over time.=20
In the largest GRB study of its kind, Schaefer found that 12 of the most =
distant GRBs - lying nearly 13 billion light years away - were all =
brighter than expected, suggesting the universe was expanding at a =
slower rate than it is today.=20
He says the fact that all 12 were brighter than would be predicted by a =
cosmological constant increases his confidence in the data. "It's like =
if you flip a coin and get 12 heads in a row," Schaefer told New =
Scientist.=20
View several graphs of his results, here: http://www.phys.lsu.edu/GRBHD/
He says that rather than pushing space apart, dark energy appears to =
have changed over time and was in fact drawing space together in the =
early universe. What that means for the fate of the universe is not =
clear, but it seems to open a Pandora's box of outlandish possibilities =
for dark energy, he says: "With quintessence, you can do anything you =
want."
Full Text at NewScientist
http://www.newscientistspace.com/article/dn8566
Comment:
Would that make the Cosmological Constant, to echo Einstein's words, =
modern cosmology's "biggest blunder?"
--=20
Posted by
Robert Karl Stonjek
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<DIV>Gamma-ray burst study may rule out cosmological constant<BR>15:15 =
11=20
January 2006 <BR>NewScientist.com news service <BR>Maggie McKee, =
Washington=20
DC</DIV>
<DIV> </DIV>
<DIV>Dark energy =96 the mysterious force that drives the acceleration =
of the=20
universe =96 changes over time, controversial new calculations suggest. =
If true,=20
the work rules out Einstein's notion of a "cosmological constant" and =
suggests=20
dark energy, which now repels space, once drew it together.</DIV>
<DIV> </DIV>
<DIV>Astronomers invoked the concept of dark energy to explain =
supernovae=20
observations in the late 1990s that the universe is not only expanding =
but=20
accelerating. The supernovae appeared dimmer =96 and therefore more =
distant =96 than=20
expected, given their red shift, which measures how much their light has =
been=20
stretched by the expansion of space.</DIV>
<DIV> </DIV>
<DIV>But it is still not clear what dark energy is. Theories range from =
a=20
"vacuum" energy of space itself which is fixed in value =96 an idea =
Einstein=20
proposed as the "cosmological constant" =96 to more exotic =
possibilities, such as=20
quintessence =96 a type of energy field that can vary over space and =
time.</DIV>
<DIV> </DIV>
<DIV>So far, supernova studies have supported the cosmological constant =
=96 one=20
recent study of 70 supernovae reported that the strength of repulsion =
given by=20
dark energy could not have changed by more than about 20% over the past =
eight=20
billion years.</DIV>
<DIV> </DIV>
<DIV>Reliable data<BR>But supernovae are too dim to be seen over the =
largest=20
cosmic distances. So some astronomers argue that gamma-ray bursts (GRBs) =
=96=20
violent, fleeting explosions that accompany the deaths of some massive =
stars =96=20
are better signposts. At about 100 times brighter than supernovae, they =
can be=20
seen at much greater distances.</DIV>
<DIV> </DIV>
<DIV>Now, astronomer Bradley Schaefer of Louisiana State University in =
Baton=20
Rouge, US, has used observations of 52 GRBs to suggest that dark energy =
has=20
changed over time. </DIV>
<DIV> </DIV>
<DIV>In the largest GRB study of its kind, Schaefer found that 12 of the =
most=20
distant GRBs =96 lying nearly 13 billion light years away =96 were all =
brighter than=20
expected, suggesting the universe was expanding at a slower rate than it =
is=20
today. </DIV>
<DIV> </DIV>
<DIV>He says the fact that all 12 were brighter than would be predicted =
by a=20
cosmological constant increases his confidence in the data. "It's like =
if you=20
flip a coin and get 12 heads in a row," Schaefer told New Scientist. =
</DIV>
<DIV> </DIV>
<DIV>View several graphs of his results, here: <A=20
href=3D"http://www.phys.lsu.edu/GRBHD/">http://www.phys.lsu.edu/GRBHD/</A=
</DIV>
<DIV> </DIV>
<DIV>He says that rather than pushing space apart, dark energy appears =
to have=20
changed over time and was in fact drawing space together in the early =
universe.=20
What that means for the fate of the universe is not clear, but it seems =
to open=20
a Pandora's box of outlandish possibilities for dark energy, he says: =
"With=20
quintessence, you can do anything you want."</DIV>
<DIV> </DIV>
<DIV>Full Text at NewScientist</DIV>
<DIV><A=20
href=3D"http://www.newscientistspace.com/article/dn8566">http://www.newsc=
ientistspace.com/article/dn8566</A></DIV>
<DIV> </DIV>
<DIV>Comment:<BR>Would that make the Cosmological Constant, to echo =
Einstein's=20
words, modern cosmology's "biggest blunder?"</DIV>
<DIV><BR>-- <BR>Posted by<BR>Robert Karl Stonjek</DIV></BODY></HTML>
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|
| User: "Len Gaasenbeek" |
|
| Title: Re: Article: Gamma-ray burst study may rule out cosmological constant |
11 Jan 2006 04:25:15 PM |
|
|
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"Robert Karl Stonjek" <stonjek@ozemail.com.au> wrote in message =
news:i0exf.213842$V7.33853@news-server.bigpond.net.au...
Gamma-ray burst study may rule out cosmological constant
15:15 11 January 2006=20
NewScientist.com news service=20
Maggie McKee, Washington DC
Dark energy - the mysterious force that drives the acceleration of the =
universe - changes over time, controversial new calculations suggest. If =
true, the work rules out Einstein's notion of a "cosmological constant" =
and suggests dark energy, which now repels space, once drew it together.
Astronomers invoked the concept of dark energy to explain supernovae =
observations in the late 1990s that the universe is not only expanding =
but accelerating. The supernovae appeared dimmer - and therefore more =
distant - than expected, given their red shift, which measures how much =
their light has been stretched by the expansion of space.
But it is still not clear what dark energy is. Theories range from a =
"vacuum" energy of space itself which is fixed in value - an idea =
Einstein proposed as the "cosmological constant" - to more exotic =
possibilities, such as quintessence - a type of energy field that can =
vary over space and time.
So far, supernova studies have supported the cosmological constant - =
one recent study of 70 supernovae reported that the strength of =
repulsion given by dark energy could not have changed by more than about =
20% over the past eight billion years.
Reliable data
But supernovae are too dim to be seen over the largest cosmic =
distances. So some astronomers argue that gamma-ray bursts (GRBs) - =
violent, fleeting explosions that accompany the deaths of some massive =
stars - are better signposts. At about 100 times brighter than =
supernovae, they can be seen at much greater distances.
Now, astronomer Bradley Schaefer of Louisiana State University in =
Baton Rouge, US, has used observations of 52 GRBs to suggest that dark =
energy has changed over time.=20
In the largest GRB study of its kind, Schaefer found that 12 of the =
most distant GRBs - lying nearly 13 billion light years away - were all =
brighter than expected, suggesting the universe was expanding at a =
slower rate than it is today.=20
He says the fact that all 12 were brighter than would be predicted by =
a cosmological constant increases his confidence in the data. "It's like =
if you flip a coin and get 12 heads in a row," Schaefer told New =
Scientist.=20
View several graphs of his results, here: =
http://www.phys.lsu.edu/GRBHD/
He says that rather than pushing space apart, dark energy appears to =
have changed over time and was in fact drawing space together in the =
early universe. What that means for the fate of the universe is not =
clear, but it seems to open a Pandora's box of outlandish possibilities =
for dark energy, he says: "With quintessence, you can do anything you =
want."
Full Text at NewScientist
http://www.newscientistspace.com/article/dn8566
Comment:
Would that make the Cosmological Constant, to echo Einstein's words, =
modern cosmology's "biggest blunder?"
--=20
Posted by
Robert Karl Stonjek
=
..........................................................................=
..
To Robert,
The confusion about Gamma-Ray bursters is due to the fact that their =
current explanation is incorrect.
A Gamma-Ray burst is observed when a superluminal star passes an =
observer.
Since the star travels faster than its image, it will actually have =
passed the observer before he will first see it, similar to the way we =
can't hear a supersonic plane coming until suddenly we hear its sonic =
boom.
"No wonder a gamma-ray burster is so intense, of such high frequency =
and of such short duration!"
"Immediately after it first appears, the star image splits into two =
historic star images. One follows the actual star in space and time at =
a progressively slower velocity, whereas the second historic star image =
travels back in space and time at a progressively slower velocity." =20
"One side effect of the above phenomenon is that as the historic star =
image first splits into two images, optical interference may result, =
causing the intensity of the image to oscillate over a period of =
seconds."
"This phenomenon has in fact been observed. =20
See: Bradley E. Schaefer, Scientific American, February 1985,
Volume 252, No. 2, Gamma-Ray Bursters, Pages 52-58."
For a complete explanation, including all the relevant formulas and a =
numerical example, see the fourth of my 'Selected Papers' titled:=20
'Frames of Reference: Part Two', under the sub-heading of:=20
'Gamma-Ray bursters'.
You will find my Selected Papers on my webside at:
http://www2.rideau.net/gaasbeek =20
Enjoy, Len.
...............................................................
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<BLOCKQUOTE dir=3Dltr=20
style=3D"PADDING-RIGHT: 0px; PADDING-LEFT: 5px; MARGIN-LEFT: 5px; =
BORDER-LEFT: #000000 2px solid; MARGIN-RIGHT: 0px">
<DIV>"Robert Karl Stonjek" <<A=20
href=3D"mailto:stonjek@ozemail.com.au">stonjek@ozemail.com.au</A>> =
wrote in=20
message <A=20
=
href=3D"news:i0exf.213842$V7.33853@news-server.bigpond.net.au">news:i0exf=
..213842$V7.33853@news-server.bigpond.net.au</A>...</DIV>
<DIV>Gamma-ray burst study may rule out cosmological constant<BR>15:15 =
11=20
January 2006 <BR>NewScientist.com news service <BR>Maggie McKee, =
Washington=20
DC</DIV>
<DIV><FONT face=3DArial size=3D2></FONT> </DIV>
<DIV>Dark energy =96 the mysterious force that drives the acceleration =
of the=20
universe =96 changes over time, controversial new calculations =
suggest. If true,=20
the work rules out Einstein's notion of a "cosmological constant" and =
suggests=20
dark energy, which now repels space, once drew it together.</DIV>
<DIV><FONT face=3DArial size=3D2></FONT> </DIV>
<DIV>Astronomers invoked the concept of dark energy to explain =
supernovae=20
observations in the late 1990s that the universe is not only expanding =
but=20
accelerating. The supernovae appeared dimmer =96 and therefore more =
distant =96=20
than expected, given their red shift, which measures how much their =
light has=20
been stretched by the expansion of space.</DIV>
<DIV><FONT face=3DArial size=3D2></FONT> </DIV>
<DIV>But it is still not clear what dark energy is. Theories range =
from a=20
"vacuum" energy of space itself which is fixed in value =96 an idea =
Einstein=20
proposed as the "cosmological constant" =96 to more exotic =
possibilities, such=20
as quintessence =96 a type of energy field that can vary over space =
and=20
time.</DIV>
<DIV><FONT face=3DArial size=3D2></FONT> </DIV>
<DIV>So far, supernova studies have supported the cosmological =
constant =96 one=20
recent study of 70 supernovae reported that the strength of repulsion =
given by=20
dark energy could not have changed by more than about 20% over the =
past eight=20
billion years.</DIV>
<DIV><FONT face=3DArial size=3D2></FONT> </DIV>
<DIV>Reliable data<BR>But supernovae are too dim to be seen over the =
largest=20
cosmic distances. So some astronomers argue that gamma-ray bursts =
(GRBs) =96=20
violent, fleeting explosions that accompany the deaths of some massive =
stars =96=20
are better signposts. At about 100 times brighter than supernovae, =
they can be=20
seen at much greater distances.</DIV>
<DIV><FONT face=3DArial size=3D2></FONT> </DIV>
<DIV>Now, astronomer Bradley Schaefer of Louisiana State University in =
Baton=20
Rouge, US, has used observations of 52 GRBs to suggest that dark =
energy has=20
changed over time. </DIV>
<DIV><FONT face=3DArial size=3D2></FONT> </DIV>
<DIV>In the largest GRB study of its kind, Schaefer found that 12 of =
the most=20
distant GRBs =96 lying nearly 13 billion light years away =96 were all =
brighter=20
than expected, suggesting the universe was expanding at a slower rate =
than it=20
is today. </DIV>
<DIV><FONT face=3DArial size=3D2></FONT> </DIV>
<DIV>He says the fact that all 12 were brighter than would be =
predicted by a=20
cosmological constant increases his confidence in the data. "It's like =
if you=20
flip a coin and get 12 heads in a row," Schaefer told New Scientist. =
</DIV>
<DIV><FONT face=3DArial size=3D2></FONT> </DIV>
<DIV>View several graphs of his results, here: <A=20
=
href=3D"http://www.phys.lsu.edu/GRBHD/">http://www.phys.lsu.edu/GRBHD/</A=
</DIV>
<DIV><FONT face=3DArial size=3D2></FONT> </DIV>
<DIV>He says that rather than pushing space apart, dark energy appears =
to have=20
changed over time and was in fact drawing space together in the early=20
universe. What that means for the fate of the universe is not clear, =
but it=20
seems to open a Pandora's box of outlandish possibilities for dark =
energy, he=20
says: "With quintessence, you can do anything you want."</DIV>
<DIV><FONT face=3DArial size=3D2></FONT> </DIV>
<DIV>Full Text at NewScientist</DIV>
<DIV><A=20
=
href=3D"http://www.newscientistspace.com/article/dn8566">http://www.newsc=
ientistspace.com/article/dn8566</A></DIV>
<DIV><FONT face=3DArial size=3D2></FONT> </DIV>
<DIV>Comment:<BR>Would that make the Cosmological Constant, to echo =
Einstein's=20
words, modern cosmology's "biggest blunder?"</DIV>
<DIV><FONT face=3DArial size=3D2></FONT><FONT face=3DArial =
size=3D2></FONT><FONT=20
face=3DArial size=3D2></FONT><FONT face=3DArial size=3D2></FONT><FONT =
face=3DArial=20
size=3D2></FONT><FONT face=3DArial size=3D2></FONT><BR>-- <BR>Posted =
by<BR>Robert=20
Karl Stonjek</DIV>
<DIV><FONT face=3DArial=20
=
size=3D2>................................................................=
...........</FONT></DIV>
<DIV><FONT face=3DArial size=3D2>To Robert,</FONT></DIV>
<DIV><FONT face=3DArial size=3D2></FONT> </DIV>
<DIV><FONT face=3DArial size=3D2>The confusion about Gamma-Ray =
bursters is due to=20
the fact that their current explanation is incorrect.</FONT></DIV>
<DIV><FONT face=3DArial size=3D2></FONT> </DIV>
<DIV><FONT face=3DArial size=3D2>A Gamma-Ray burst is observed =
when a=20
superluminal star passes an observer.</FONT></DIV>
<DIV><FONT face=3DArial size=3D2>Since the star travels faster than =
its image, it=20
will actually have passed the observer before he will first see it, =
similar to=20
the way we can't hear a supersonic plane coming until suddenly we hear =
its=20
sonic boom.</FONT></DIV>
<DIV><FONT face=3DArial size=3D2></FONT> </DIV>
<DIV><FONT face=3DArial size=3D2>"No wonder a gamma-ray burster is so =
intense, of=20
such high frequency and of such short duration!"</FONT></DIV>
<DIV><FONT face=3DArial size=3D2></FONT> </DIV>
<DIV><FONT face=3DArial size=3D2>"Immediately after it first appears, =
the star=20
image splits into two historic star images. One follows the =
actual star=20
in space and time at a progressively slower velocity, whereas the =
second=20
historic star image travels back in space and time at a progressively =
slower=20
velocity." </FONT></DIV>
<DIV><FONT face=3DArial size=3D2></FONT> </DIV>
<DIV><FONT face=3DArial size=3D2>"One side effect of the above =
phenomenon is that=20
as the historic star image first splits into two images, optical =
interference=20
may result, causing the intensity of the image to oscillate over a =
period of=20
seconds."</FONT></DIV>
<DIV><FONT face=3DArial size=3D2></FONT> </DIV>
<DIV><FONT face=3DArial size=3D2>"This phenomenon has in fact been =
observed. =20
</FONT></DIV>
<DIV><FONT face=3DArial size=3D2>See: </FONT><FONT face=3DArial =
size=3D2>Bradley E.=20
Schaefer, Scientific American, February 1985,</FONT></DIV>
<DIV><FONT face=3DArial size=3D2>Volume 252, No. 2, Gamma-Ray =
Bursters, Pages=20
52-58."</FONT></DIV>
<DIV><FONT face=3DArial size=3D2></FONT> </DIV>
<DIV><FONT face=3DArial size=3D2>For a complete explanation, including =
all the=20
relevant formulas and a numerical example, see the fourth of my =
'Selected=20
Papers' titled: </FONT></DIV>
<DIV><FONT face=3DArial size=3D2>'Frames of Reference: Part Two', =
under the=20
sub-heading of: </FONT></DIV>
<DIV><FONT face=3DArial size=3D2>'Gamma-Ray bursters'.</FONT></DIV>
<DIV><FONT face=3DArial size=3D2></FONT> </DIV>
<DIV><FONT face=3DArial size=3D2>You will find my Selected Papers on =
my webside=20
at:</FONT></DIV>
<DIV><FONT face=3DArial size=3D2><A=20
=
href=3D"http://www2.rideau.net/gaasbeek">http://www2.rideau.net/gaasbeek<=
/A> =20
</FONT></DIV>
<DIV><FONT face=3DArial size=3D2></FONT> </DIV>
<DIV><FONT face=3DArial size=3D2>Enjoy, Len.</FONT></DIV>
<DIV><FONT face=3DArial=20
=
size=3D2>...............................................................<=
/FONT></DIV></BLOCKQUOTE></BODY></HTML>
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