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

[coldcreation]

...


This discussion is a continuation from here, where is was off-topic.


In the 1990’s two teams announced the results of their investigations that had for aspiration to determine the deceleration parameter, the density parameter omega, and its relation to the geometry of the universe (the ratio of energy density to critical density).

The Supernova Cosmology Project, led by astronomer Saul Perlmutter (et al) of Lawrence Berkeley National Laboratory in California, and the High-z Supernova Search Team headed by Brian Schmidt (et al) of Australia National University, Siding Springs Observatories and Mount Stromolo in Australia, and Robert Kirshner (et al) of Harvard-Smithsonian Center for Astrophysics, studied distant supernovae SNe type Ia in an attempt to determine the value of omega (the ratio of the energy density of the universe to the critical density).

With the help of Hubble Space Telescope (HST) they were able to pin down the locations of supernovae Type Ia that exploded some four to seven billion light-years ago. The outcome of the investigation came as a shock (to say the least) to both teams, and detonated an implosion that shook the rest of the scientific community—within which the unity was already questionable. The 1998 SNe Ia observational data took those fissures and blew them apart, creating a situation of semi-mayhem (exemplified by the media clippings below) with alarming consequences:

Distant supernovae and their host galaxies appear to be receding slower than permitted by Hubble’s Law (the proportionality between redshift and distance). Remarkably, the observations are consistent with an accelerating expansion of the cosmos.

Cosmologists Ponder Missing Energy “Cosmologists gather at Fermi National Laboratory in effort to explain compelling new evidence that the universe is expanding at an accelerating rate and to understand what appears to be an unknown form of energy associated with vacuum of space, the so-called ‘missing energy’ of the universe; if both current theory and new observations are correct, this energy must be acting as repulsive force to counteract gravity’s restraining influence and thus speed up cosmic expansion” (New York Times, May 5, 1998 Sec: F Science Desk p. 1). Wary Astronomers Ponder An Accelerating Universe (New York Times, March 3, 1998 Sec: F Science Desk p. 1)

Revolution in Cosmology …something is amiss. At the very least, the expansion is not decelerating as rapidly as once though. Either scientists must reconcile themselves to kooky energy, or they must modify or abandon inflation. (Scientific American, Jan. 1999 Vol. 280, 1

Accelerating the Cosmos “The cosmological constant, also called lambda...is a uniform, background energy permeating all of space. This energy gives space itself a sort of springiness, counteracting gravity on large scales…It came as a shock…the universe appeared to contain twice as much energy in the cosmological constant as it did in matter. POW…Thunderstruck astronomers…particle physicists are studying the structure of space to determine just what lambda might be…funny energy…gravity that bends space…slightly illicit…cosmological constant was mentioned as a possible culprit, but that reasoning still seemed to strange to take seriously…a huge cosmological constant…some form of energy we don’t understand…weird, fluid-like substance called quintessence, a squishy possibility…“This led me to reconsider my theoretical prejudices. I now think it is very reasonable that there should be a cosmological constant” [the latter is a quote from S. Hawking] (Astronomy, Oct. 1999 Vol. 27, 10, p. 44-51)

It was thought that the SNe survey might pin-down the Hubble constant and carve order out of the general chaos. Now, unintuitively, we have a situation where not only are galaxies undecelerated but the galaxies appear to be accelerated—faster and faster as the radius of the universe tends toward infinity.


Light curves from distant supernovae were raising the peculiar specter that Einstein’s cosmological constant was real. The observations had then to be interpreted in such a way that they would not viscerally oppose the finely tuned expansion of inflation. The possibility that the new greatest blunder might revive some of the anti-big-bang rhetoric of the early 1950's loomed. That is to say, confronted with choice of reintroducing the fudge factor or sacking eight decades of theoretical cosmology, physicists had to scramble fast, and scramble fast they did.


This thread is designed to study the implications of the latest data and differing interpretations of the evidence.


CC

[coldcreation]

...

• The large shells of radiation and material emitted by distant (ancient) supernovae appear to have a greater area than they would in a topologically flat space, making the source look very faint.
  
  
• The visible universe appears larger, deeper, younger, and emptier than previously suspected.
  
  
• Unexpected dimness of early supernovae gives the impression they are further away than their redshifts indicate, altering the predicted structure of the cosmos.
  
  
• These observations indicate that 96 percent of the matter and energy in the universe is missing (dark).
  
  
• Light from very remote objects takes longer to reach Earth—as if time and space (and the light propagating through it) were continually and increasingly ‘stretched’ with larger distances.
  
  
• The universe could be as young as 12.5 billion years old—a figure at odds with the age of some of the objects in it.

The supernovae survey (especially the one led by led by astronomer Saul Perlmutter) would set the astronomical community up for another de facto partition—fault-lines between cosmological theories and images clashing dissonantly, especially those preservation schemes proposed by the ones astride them.

The sole permutation between forecasts and the outcome of received data, the slight variation from a smooth Hubble flow (25% off-target), coupled with the recent compelling evidence that the total mass-energy density is insufficient to yield a flat universe has proved to be sufficient to set in accelerated motion the academic continental divide—and not without large seismic tremors.

When cosmologists realized their ship was sinking (due to the tidal-shock-wave), they grabbed their lifeboat (the cosmological constant) and left the women and children, their staff and sponsors, to drown.


Nobody was prepared physically or emotionally, i.e., spiritually, to deal with the conclusions coming to surface in the late 90s. Before 1998, modern cosmology had already begun taking on water. Since 1998, modern cosmology has capsized. The new SNe Ia observational results were not the anticipated circumstances to encourage a direct confrontation with realities, least of all with the realities of the Friedmann or inflationary world-views. Modern cosmology has surrounded itself with myth, evaded the past, and thus eluded the future.

The expansion set on cruise control, now was out-of-control.

CC

[coldcreation]

...



It is entertaining to contemplate what course cosmology and general relativity would have taken had Einstein not abolished the cosmological term, and sat back to await corroboration by observations. Einstein would have had to wait until 1998 for the official confirmation of his discovery.

Perhaps he would have said something like: “If the cosmological term exists, then away with the expanding universe.”

Yet, certainly when seen in terms of the fundamental antithesis between the modernism of early general relativity and the reintroduction of lambda into contemporary cosmology, it was not so much the grandeur of such a theme contained in Einstein’s equations that carried weight; more directly and deeply significant was the relationship between lambda and the concept of a static universe embodied in the general theory, both as image and act.

The Supernovae Ia fireworks festivities backfired on the crowd, leaving several victims, including at least three fatalities: The Friedmann triptychs unfortunately did not make it. Perhaps the most striking of the casualties now listed in critical condition: the inflationary expansion model and all the more recent analogues that predicted a flat universe.

Today, in the face of contradictory evidence, cosmologists have resurrected a fragment from the debris of relativity and have found for it a new identity and have affirmed thus its ‘material’ qualities. (One mans trash is another man treasure; so the saying goes). Recent interpretations of observational data have tilted the balance in favor of a new-nonzero-cosmological constant, dubbed dark energy.

In the eyes of the beholder, a cosmological constant-dominated universe expands endlessly and is literally driven by a motor-like force: with the same name that Einstein attributed to the term in his equations designed to mediate equilibrium and stability of the universe.



CC

[PhysBang]

Originally Posted by coldcreation

Nobody was prepared physically or emotionally, i.e., spiritually, to deal with the conclusions coming to surface in the late 90s. Before 1998, modern cosmology had already begun taking on water. Since 1998, modern cosmology has capsized. The new SNe Ia observational results were not the anticipated circumstances to encourage a direct confrontation with realities, least of all with the realities of the Friedmann or inflationary world-views. Modern cosmology has surrounded itself with myth, evaded the past, and thus eluded the future.

Except that this description of the history of cosmology is pure fantasy. Lemaitre came up with the mathematics to describe the current model in the 1920s. People had been analyzing the models involved for decades. The change to cosmology did not overturn the majority of previous work in the field and meshed with other empirical tests.

[coldcreation]

Originally Posted by PhysBang

Except that this description of the history of cosmology is pure fantasy. Lemaitre came up with the mathematics to describe the current model in the 1920s. People had been analyzing the models involved for decades. The change to cosmology did not overturn the majority of previous work in the field and meshed with other empirical tests.

Check out some more press clipping from 2001.

Brave New Cosmos: Making Sense of Modern Cosmology: Plan B for the Cosmos: “New discoveries have challenged long-held theories about the evolution of the universe…cosmic expansion is accelerating…an idea once considered laughable, even after a few beers…an odd kind of energy known as quintessence…we have been missing most of the story…The bulk is a ubiquitous “dark energy” with a strange and remarkable feature: its gravity does not attract. It repels. Whereas gravity pulls… The universe is a battleground between two tendencies, and repulsive gravity is winning… Where does the energy come from? Such energy is a venerable notion that dates back to Albert Einstein and his attempt in 1917 to construct a static model of the universe…he had to introduce vacuum energy…These concepts may sound strange…a serious flaw…That seems bizarre… Extrapolating back in time, vacuum energy gets even more paradoxical…our universe was the size of a grapefruit…that seems ludicrous to expect from the real world. This need for almost supernatural fine-tuning is the principle motivation for considering alternatives to the cosmological constant… Over the long term, all of us will be left to ponder the profound implications of these revolutionary discoveries. They lead to a sobering new interpretation of our place in cosmic history… Most researchers, however, had a real distaste for the cosmological constant. Now the majority accept it, or its allied concept, quintessence… Could the enthusiasm generated by inflation and its offshoots conceal a monstrous error?” (Scientific American Jan. 2001 Vol. 284 p. 37, 54, 58)

I would say my description of the SN events is mild in comparison.


CC

[PhysBang]

If by "mild" you mean "delusional", then yes. Unfortunately, the Scientific American author (if that is really the origin of the quote--there seems to be some typos involved) also makes some basic mistakes in his or her description.

The positive value of the cosmological constant was not taken seriously because there was no measurement of it. Now there is a measurement of it, so it is taken seriously.

[coldcreation]

Originally Posted by PhysBang

If by "mild" you mean "delusional", then yes.

Careful, your use of words is borderline ad hom. Attack the subject, not the person.

Originally Posted by PhysBang

Unfortunately, the Scientific American author (if that is really the origin of the quote...

You sound surprised...The origin of the quote is Scientific American.

Originally Posted by PhysBang

...--there seems to be some typos involved) also makes some basic mistakes in his or her description.

The fact is, an accelerated expansion was not predicted by the standard model (which was based on the FLRW metric, the three Friedmann models).

Originally Posted by PhysBang

The positive value of the cosmological constant was not taken seriously because there was no measurement of it. Now there is a measurement of it, so it is taken seriously.

If the measurement of the value of lambda was pending then all possibilities should have been considered seriously as potentially operational.

Originally Posted by PhysBang

Except that this description of the history of cosmology is pure fantasy.

It is rather pure fantasy that 96% of the mass-energy density is thought to be "dark" stuff.

Theories make predictions. When those predictions turn out to be erroneous, the theory is either modified or abandoned. In this case the theory (the old pre-1998 standard model) was modified (lambda-CDM). My contention (opinion) is that is should have been discarded unilaterally.

Originally Posted by PhysBang

Lemaitre came up with the mathematics to describe the current model in the 1920s.

Neither Lemaître nor his disciples predicted an accelerated expansion. The idea was just too kooky. Why, because something outside of physics (dark energy and nonbaryonic dark matter, in profuse quantities) would be required to justify the otherwise linear regime.

The favored possibility described a universe in which omega is precisely equal to one, the critical density, with a one-to-one relation between the density of the cosmos and its spatial curvature, i.e., this model was a flat, Euclidean (with zero curvature). The velocity of expansion tends to zero as its radius approaches infinity.

That prediction obviously failed.

But then again, there were two other possibilities (on the back burner just in case): one with a closed spherical geometry; it expands and collapses to infinite density in a finite time. There is enough gravitating mass to halt the expansion and reverse it, leading to a big crunch.

And finally, one with a hyperbolic geometry that expands for ever, tending to infinity with a finite velocity. The galaxies are undecelerated as there is not enough gravitating mass to stop expansion or to slow it down.


The new findings reflect none of the above.

Originally Posted by PhysBang

People had been analyzing the models involved for decades...

True, and prediction were made. It would have been sweet had predictions coincided with what is observed in nature.

That is the scientific method...



CC

[modest]

Originally Posted by coldcreation

You sound surprised...The origin of the quote is Scientific American.

That same article appears again in their "the once and future COSMOS" 2002 special edition which I still have (I never throw anything away) page 43ish-46ish. That was a really good special edition, and, believe it or not, you can get the whole thing online

The once and future Cosmos - pdf

-modest

[PhysBang]

Originally Posted by coldcreation

Careful, your use of words is borderline ad hom. Attack the subject, not the person.

Yes, what you wrote is delusional.

You sound surprised...The origin of the quote is Scientific American.

I'm not surprised. Scientific American is often a good resource for bad physics.

The fact is, an accelerated expansion was not predicted by the standard model (which was based on the FLRW metric, the three Friedmann models).

OK, there is no FLRW metric.

There is the Robertson-Walker metric.

This is used in the Friedmann models. And it is used in the Lemaitre models. (The "F" and the "L".)

The Lemaitre models have accelerated expansion. They were developed in the 1920s and studied since then.

If the measurement of the value of lambda was pending then all possibilities should have been considered seriously as potentially operational.

Some scientists did seriously consider the possibility. The current value for the cosmological constant is very, very low compared to what it could be, so it was not measured in many tests. That it wasn't measured in so many tests (being below the threshold of measurement) could be the reason many scientists though that it was zero.

It is rather pure fantasy that 96% of the mass-energy density is thought to be "dark" stuff.

Fantasy that is actually measured in many different ways, yes.

Theories make predictions. When those predictions turn out to be erroneous, the theory is either modified or abandoned. In this case the theory (the old pre-1998 standard model) was modified (lambda-CDM). My contention (opinion) is that is should have been discarded unilaterally.

You are welcome to your opinion. I'm sure you would rather have an ad hoc explanation that doesn't fit the facts.

Neither Lemaître nor his disciples predicted an accelerated expansion.

What are your readers supposed to do when you simply outright lie? You write this crap like the only way to do science is to come up with any crazy idea as long as it has nothing to do with any measurement and then wait until there is a lucky observation. Cosmologists came up with a framework of actually measuring the properties of the universe and then actually measured these properties.

The idea was just too kooky. Why, because something outside of physics (dark energy and nonbaryonic dark matter, in profuse quantities) would be required to justify the otherwise linear regime.

WTF is a "linear regime"? The universe may simply be more than you can imagine and comprehend.

The favored possibility described a universe in which omega is precisely equal to one, the critical density, with a one-to-one relation between the density of the cosmos and its spatial curvature, i.e., this model was a flat, Euclidean (with zero curvature). The velocity of expansion tends to zero as its radius approaches infinity.


That prediction obviously failed.

This was a favoured result, but not one that was predicted. Cosmologists were committed to measuring, not dictating.

But then again, there were two other possibilities (on the back burner just in case): one with a closed spherical geometry; it expands and collapses to infinite density in a finite time. There is enough gravitating mass to halt the expansion and reverse it, leading to a big crunch.

And finally, one with a hyperbolic geometry that expands for ever, tending to infinity with a finite velocity. The galaxies are undecelerated as there is not enough gravitating mass to stop expansion or to slow it down.


The new findings reflect none of the above.

Not just matched none of the above, but showed systematic results that provided a measurement of cosmological parameters.

True, and prediction were made. It would have been sweet had predictions coincided with what is observed in nature.

That is the scientific method...

The predictions made were how to make cosmological measurements. One could also consider the measurements made by one technique to be a prediction. Then one can look at the measurements made by another technique as another prediction.

I would be interested to find out just what issue of Scientific American that original quote came from, since it is not the one that modest posted.

[Mike C]

CC

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?

Another common acceptance of the BBT is that it is a 'uniform' expansion that is additive as in a baloon analogy?

What is the largest redshift observed by these SN?
If I remember right, it was less than 3 that is not a deep penetration of space as compared to the HDF's that see RS's of 7+.

So these SN are not suitable for evaluating the universe distances with such short observations.

Mike C