SNe Ia, Implications, Interpretations, Lambda-CDM...

[modest]

 

So the SNe Ia data is more than just a signature of Lobachevkian geometry, it is the confirmation of hyperbolicity based on empirical evidence

 

Obviously not with the FLRW metric. If you think you can solve the friedman equations with significant negative K and no cosmological constant to get a fit with the SNe 1a observations then present it. Otherwise we need to take the word of the people who did the study and their peers.

 

I'm working on it.

 

CC

 

I think that's fantastic. The FLRW luminosity distance formula is:

 

[math] D_L=\frac{c(1+z)}{H_0\sqrt{\Omega_K}}S(I)[/math]

 

where S = sinh for [imath]\Omega_K>0[/imath]

S = 1 for [imath]\Omega_K=0[/imath]

S = sin for [imath]\Omega_K<0[/imath]

and...

 

[math]I=\sqrt{|\Omega_K|}\int_{0}^zdz'{[(1+z')^2(1+\Omega_Mz')-z'(2+z')\Omega_\Lambda]}^{-1/2}[/math]

 

Interestingly, you can find this function in this paper:

The Cosmological Constant

equation 25

where it is solved for different fiducial models of the universe including the one you're interested in. This is interesting because the paper was written in 1992 as an exploration of possible consequences of a cosmological constant before the supernova data came in. It basically predicts what was subsequently observed - at least as a possibility. I didn't read the whole paper - but it definitely should support the idea for you that lambda is not a major change in the standard model and is NO fundamental change in the underlying structure of the model.

 

This is simply a parameter that we have known about, is also known about in another branch of physics, and can be successfully solved for.

 

-modest

[PhysBang]

I don't think it was sloppy, it's just that at the time (again pre-1998) dark energy (or even Einstein's lambda) were not considered to the extent observed today. And so the deceleration parameter, practically alone, was thought to be sufficient for the determination of the global geometry, since it included the mass-energy (baryonic matter and real energy) terms intrinsically. That's the short version...

 

Remember the old dictum: “matter tells spacetime how to curve, and curved space tells matter how to move” John Wheeler

 

Or this one: Curvature results from mass or momentum, and the curvature defines the path of least-resistance for motion.

Wheeler was discussing a general, approximate way to describe general rel

"The bulk is a ubiquitous dark energy with a strange and remarkable feature: its gravity does not attract. It repels. Whereas gravity pulls…" (See Brave New Cosmos: Making Sense of Modern Cosmology: Plan B for the Cosmos: Scientific American Jan. 2001 Vol. 284 p. 37, 54, 58)) You will find this exact phrase here (in the link provide by modest), page 42. It was written by Jeremiah P. Ostriker and Paul J. Steinhardt

That is a statement on the nature of the cosmological constant, something known prior to its verification through measurement. This is not the argument that you, and no scientist, presented.

The big difference with gravity and dark energy (both of which are thought to permeate all of space) is that one can be experienced by the senses and experiments can be carried out to test its potential, whereas the other not (regardless of the physical mechanism involved in the phenomenon). In other words, we know gravity exists and is here to stay. The other not.

Really? You really directly observe gravity? What does it look like?

Apparently, the first basic rule of life in cosmology is self-preservation, which comes before any scruples, delicacy, natural laws or physical principles.

You must have what it takes to be a cosmologist.

[coldcreation]

 

The big difference with gravity and dark energy (both of which are thought to permeate all of space) is that one can be experienced by the senses and experiments can be carried out to test its potential, whereas the other not (regardless of the physical mechanism involved in the phenomenon). In other words, we know gravity exists and is here to stay. The other not.

 

Really? You really directly observe gravity? What does it look like?

 

 

 

 

What does dark energy feel like?

 

[Edited to add: Gravity is experienced by the senses and experiments can be carried out to test its potential.]

 

 

The counter argument inevitably is based on the fact (if it even exists) that dark energy is imperfectly measurable or not measurable at all. Something needs to be implemented, or there is no explanation for the SNe Ia data... [...within the framework of the standard model. Edit].

 

So what to do?

 

 

The problem is reminiscent of the practice of benchmarking, whereby performance is measured against a set of given standards. Kaplan, R., and Norton, D., The Balanced Scorecard, 1996, argue, “You can’t manage what you can’t measure, and you can’t measure what you can’t describe.”

 

In the field of cosmology there may arise observations that remain obstinately defiant of objective quantification. All the mathematics in the world cannot replace a correct interpretation or good judgment. How to prove those interpretations is of course the question. Some will argue that the dark energy/dark matter parameters have been measured (leaving a miserable 4% of the real universe intact). That said, it is an error to treat mathematics as god. What counts (pun non-intended) is that physics must be verifiable, factual when possible and that it be utilized to make accurate interpretations.

 

Clearly there is a risk here. If physical laws are relaxed, or worse, vacated, the result inevitably leads towards something that is not physics, not natural, less desirable, especially when the goal is to explain the physical world. Tough standards, therefore, should be maintained and imposed to reduce the risk of cosmology running amok. For now, few seem to believe that cosmology should stick to the natural laws, despite the current low-credibility factor with respect to a mysterious dark force dominating the cosmos.

 

This is a risk, yet perhaps worth taking to place the field of cosmology back into the domain of physics. This policy might help reinvigorating a constructive debate over such important issues as the SNe Ia survey results.

 

 

_________________________________

 

 

 

[Edited to add: MikeC, this thread deals with the SNe Ia as standard candle. If you dispute this claim start a new thread on that topic. Gravity (whether it be Newtonian of Einsteinian), too, is the subject of another thread. Thanks in advance.]

 

 

 

 

CC

[Mike C]

Really? You really directly observe gravity? What does it look like?

 

The 2 experiments by Cavendish and Boys have established a constant for determining gravity.

This is proof that gravity is an attractive force.

 

You should also be aware of the effects of both gravity and Newtons 1st Law of Motion that states 'an object will continue in a straight line (linear momentum) unless affected by an external force to redirect its path.

So as a passenger in a car making a turn, both forces are acting here when we remain glued to the car seat (gravity) and sway sideways when being forced to lean (LM) as the car turns.

 

Mike C

 

.

[Mike C]

To All

 

The SN 1a's are the most unreliable sources for use as 'distance candles because of their wide margin of error (+/-5). See reply 12 on page 2 of this thread.

You can also add that those SN's cannot be corrected for 'local space velocities' or the direction of the explosion materia approaching us or moving laterally to us.

Lateral motion could cause a magnitude reduction in relation to a lateral spread (time dilation) that elongates the wave pattern, IMO.

 

Mike C

[PhysBang]

To All

 

The SN 1a's are the most unreliable sources for use as 'distance candles because of their wide margin of error (+/-5). See reply 12 on page 2 of this thread.

In what units? Why don't you repeat your argument in some statistical detail.

You can also add that those SN's cannot be corrected for 'local space velocities' or the direction of the explosion materia approaching us or moving laterally to us.

What is the estimated effect of these local space velocities? What is their estimated impact on the measurements of these events?

Lateral motion could cause a magnitude reduction in relation to a lateral spread (time dilation) that elongates the wave pattern, IMO.

What is the estimated effect of this lateral motion? What is its estimated impact on the measurements of these events?

[PhysBang]

The problem is reminiscent of the practice of benchmarking, whereby performance is measured against a set of given standards. Kaplan, R., and Norton, D., The Balanced Scorecard, 1996, argue, “You can’t manage what you can’t measure, and you can’t measure what you can’t describe.”

Before there were any reports of SNe Ia observations, there were published frameworks about just how to measure the effects of dark energy. A quick glance over any of these papers should reveal the fundamentals of ow to not only measure the effect of the energy, but also how to look for finer measurements on its behaviour, either in the paper itself or in the references of the paper.

[coldcreation]

Before there were any reports of SNe Ia observations, there were published frameworks about just how to measure the effects of dark energy. A quick glance over any of these papers should reveal the fundamentals of [h]ow to not only measure the effect of the energy, but also how to look for finer measurements on its behaviour, either in the paper itself or in the references of the paper.

 

 

That is certainly so, but that doesn't make it any more real, natural or physical. I argue that there is nothing physical about it, and for that reason, it is a pity that cosmology is not held up to the same standards as all other fields of science -- especially in light of the post-1998 observations, when it became a the principle ingredient of the standard model.

 

 

Here is another little taste of some post-1998 dark energy (and its potential effects on the environment) news.

 

Edited to add: Note; these quotes are by astronomers, for the most part, directly involved in the SNe Ia survey.]

 

 

In a special issue of Astronomy titled Origin & Fate of the Universe (2004) Turner is quoted regarding current cosmic snags: “It doesn’t take a genius to say that all of the ideas out there today are wrong—or incomplete at best.”

 

“If you thought the universe was hard to comprehend before,” said Michael Turner (University of Chicago), then you’d better take some smart pills, because it’s only going to get worse.” (Time, June 25, 2001, p. 50). And in the same article worse came. An ”expert” on the fate of the universe from University of Michigan, Fred Adams, cogitates that atoms will become larger than the universe in a few trillion years (p. 56).

 

Joseph Lykken, a physicist at the Fermi National Accelerator Laboratory (Fermilab) in Batavia, cries out after seeing the fireworks display: “I could go home and be happy,” but later adds, “theorists don’t have a clue” about the identity of dark energy. And there are plenty of like-minded astronomers out there.

 

Riess et al recently grouped under the name Great Observatories Origins Deep Survey (GOODS). The word Origins had to be added, otherwise they would have been left with GODS program. The latter is possibly most fitting, as Riess admits, referring to dark energy “we still have almost no clue what it is.” (Britt 2004)

 

"In some ways it sounds more like science fiction than fact," alleged Dr. Robert Caldwell, a Dartmouth physicist who described this apocalyptic prospect in a 2003 paper with Dr. Marc Kamionkowski and Dr. Nevin Weinberg, California Institute of Technology.

 

A cosmological constant dominated universe is “the bleakest of all outcomes, offering no chance to do cosmology, no chance for rebirth—just a long, cold death,” observes a Brian Schmidt.

 

"It's weird negative pressure," said Dr. Krauss. (Oberbye 2004)

 

“It crosses a boundary of good taste,” it’s “bad news stuff,” says Dr. Caldwell about the phantom energy. (Oberbye 2004)

 

Like a curse that won’t go away, Dr. Kirshner had dismissed the energy as “too strange” back in 1998. “It sounds wacky” he knows, but thinks “we’re in a situation where we’re going to need a really new idea. We’re in trouble; the way out is going to be new imaginative things. It might be our ideas are not wild enough, they don’t question fundamentals enough.” (Oberbye 2004, From Space, A New View Of Doomsday, New York Times)

 

 

 

One thing seems certain: the fudge factor is not going away, however much some astronomers might wish it to.

 

The new dark fudge factor in its insidious afterlife is nonsense.

 

 

 

The new lambda is a fudge factory.

 

 

 

CC

[PhysBang]

An yet, despite their distaste for dark energy, all these astronomers embrace dark energy. They do this because without knowing it`s specifics, they know it is there. To say otherwise would be to ignore the evidence.

[modest]

Cosmologist are always going on in their poetical style. Saying this is earth shattering and that changes everything. Here you see god and there is the birth-cry of the infant universe. I take such things with a grain of salt.

 

"you’d better take some smart pills"

 

"GODS program. The latter is possibly most fitting, as Riess admits, referring to dark energy"

 

...just mucks up the issue.

 

-modest

[coldcreation]

An yet, despite their distaste for dark energy, all these astronomers embrace dark energy. They do this because without knowing it`s specifics, they know it is there. To say otherwise would be to ignore the evidence.

 

No one really knows if dark energy exists or not. Astronomers do not "know it is there."

 

Why would it be ignoring the evidence to say otherwise? Empirical evidence can (and does) support several different hypotheses (or interpretations), one of which does not include a dark energy component.

 

 

 

 

You can take lambda out of the trash, but you can't take the trash out of lambda!

 

 

 

 

CC

[modest]

You can take lambda out of the trash, but you can't take the trash out of lambda!

 

That's a good one

[Mike C]

In what units? Why don't you repeat your argument in some statistical detail.

 

Since the astronomers use the 'parcec' as their unit of measuring distance, then that would be the unit used.

These measurements I gave were done on the Virgo Cluster of galaxies.

The VC is determined to be at a distance of 16.7 mega parsecs but the error margin would have to be just parsecs that are equal to 3.26 light years.

 

What is the estimated effect of these local space velocities? What is their estimated impact on the measurements of these events?

 

Local space velocities can reach levels of about 1000 km/s.

I did an evaluation of the Virgo Cluster galactic velocities and masses and discovered (calculated) that M86 has an approach velocity to us at about 1000 km/s.

What attracted me to do this evaluation was that M86 has a 'blue shift' of

60 km/s toward us whille the cluster itself is considered to be receding from us at about 1100 km/s.

 

What is the estimated effect of this lateral motion? What is its estimated impact on the measurements of these events?

 

My opinion is that an explosion moving toward us would increase the magnitude of the light and keep it more centrally concentrated.

While on the other hand, an explosion moving laterally to us would be more widened and its light more scattered over a wider distance (angular size).

These two types of directions could create a curvature that would create the illusion that the objects are at different distances and with the light curve being wider, would create the illusion of 'time dilation' with a lower magnitude and widened light curve.

 

Mike C

[Erasmus00]

Why would it be ignoring the evidence to say otherwise? Empirical evidence can (and does) support several different hypotheses (or interpretations), one of which does not include a dark energy component

 

The alternative seems to be throwing out general relativity, which many find more distasteful. Even your proposed solution (a de-sitter type model) can't work with the observed matter density (hence the need for a cosmological constant Lambda (i.e. dark energy)).

-Will

[PhysBang]

The alternative seems to be throwing out general relativity, which many find more distasteful. Even your proposed solution (a de-sitter type model) can't work with the observed matter density (hence the need for a cosmological constant Lambda (i.e. dark energy)).

-Will

His model has the cosmological constant already built in. Just no matter.

[PhysBang]

Since the astronomers use the 'parcec' as their unit of measuring distance, then that would be the unit used.

These measurements I gave were done on the Virgo Cluster of galaxies.

The VC is determined to be at a distance of 16.7 mega parsecs but the error margin would have to be just parsecs that are equal to 3.26 light years.

What does this have to do with SNe Ia observations? What are the distances and redshifts involved?

Local space velocities can reach levels of about 1000 km/s.

I did an evaluation of the Virgo Cluster galactic velocities and masses and discovered (calculated) that M86 has an approach velocity to us at about 1000 km/s.

What attracted me to do this evaluation was that M86 has a 'blue shift' of

60 km/s toward us whille the cluster itself is considered to be receding from us at about 1100 km/s.

What does this have to do with SNe Ia observations? What are the distances and redshifts involved?

My opinion is that an explosion moving toward us would increase the magnitude of the light and keep it more centrally concentrated.

While on the other hand, an explosion moving laterally to us would be more widened and its light more scattered over a wider distance (angular size).

These two types of directions could create a curvature that would create the illusion that the objects are at different distances and with the light curve being wider, would create the illusion of 'time dilation' with a lower magnitude and widened light curve.

Do you have any actual physical theory to back up this opinion? Can we see this physical behaviour in a toy model? Can we produce any guess as to its magnitude?

[modest]

As I have said on other posts, the SN 1a's are not reliable distance indicators, IMO, because of the huge variations in the temperatures of white dwarf stars and and also in their masses.

How then can you give any credibilty to these SN as accurate distance candles?

 

This is not an uncommonly held position from what I'm reading. In particular the average metallicity may be changing with time.

"Predicted and Observed Evolution in the Mean Properties of Type 1A Supernovae with Redshift"

 

Might be seen to support this position. At the least it shows some of the deleterious corrections needed.

 

-modest