Doubt on reliability of astronomical yardstick

[LogicalFallacy]

http://www.nature.com/news/supernova-s-messy-birth-casts-doubt-on-reliability-of-astronomical-yardstick-1.22066

 

A short summary in my own words. The brightness of supernova has until recently been considered fairly standard and a reliable way to measure expansion of the universe. However recent discoveries case doubt on this reliability and throw into doubt the reliability of the data that is used to determine the expansion rate of the universe.

 

The comments section is also interesting. One person stated that there is a problem with the expansion of the universe theory - namely that galaxies are not expanding, but the space between galaxies is. The person thought this was an inconstancy in the theory - why should space between galaxies expand, but space in galaxies not expand? Can any of our more knowledgeable folks shed light?

 

Hmm actually found a blog that might explain that question: http://backreaction.blogspot.co.nz/2017/08/you-dont-expand-just-because-universe.html

[bornagainathiest]

This issue has been bubbling in astronomical circles for a few years, LF.

Ever since anomalous supernovae were discovered... not blowing up according to the book.  The book in this case being the theory proposed by Subrahmanyan Chandrasekhar in 1931.

 

http://www.pbs.org/wgbh/nova/blogs/physics/2012/01/the-chandrasekhar-limit-the-threshold-that-makes-life-possible/

 

This discovery was made by Ralph Fowler, who would later become Chandrasekhar’s graduate supervisor. But Chandrasekhar realized what Fowler had missed: The high-energy electrons inside the white dwarf would have to be traveling at velocities near the speed of light, invoking a set of bizarre relativistic effects. When Chandrasekhar took these relativistic effects into account, something spectacular happened. He found a firm upper limit for the mass of any body which could be supported by electron degeneracy pressure. Once this limit—the Chandraskehar limit—was exceeded, the object could no longer resist the force of gravity, and it would begin to collapse.

 

This collapse initiates the supernova explosion.  

Type 1A supernovae explosions, to be precise.  Which occur in binary star systems, when white dwarf stars siphon off gas from the outer layers of their partner (usually a mature, ordinary star) and compress the gaseous material onto their surfaces.  With nowhere else to go this gas builds up on the white dwarf, with a corresponding increase in density and temperature. When so much of it has built up the limit is exceeded and the star undergoes a catastrophic failure - collapsing and imploding in the blink of an eye.  A supernova explosion is the result that we see.

 

 http://hubblesite.org/hubble_discoveries/dark_energy/de-type_ia_supernovae.php 

Other types of supernovae exist (like the core-collapse of a single, giant star) but it was thought only type 1A's were as similar as peas in a pod.  The logic of the argument seemed impeccable. If the trigger for collapse is a fixed mathematical limit that nature cannot exceed (like the speed of light) then it follows that the resulting supernovae explosions must all have the same energy.  If they all have the same energy, then once you've compensated for certain other variables, you should have a 'standard candle' that you can use as a yardstick with which to measure the entire universe. But it now seems that there are loopholes in the logic of this argument and a re-evaluation of the cosmic distance ladder is needed.  

 

THE   COSMIC   DISTANCE   LADDER

 

 

 

The ladder is 'somewhat' hierarchical.

While certain methods come into their own at certain scales (i.e., there are NO Cepheid variable stars or supernovae within the solar system) it is more or less true that each the accuracy of each rung of the ladder depends to a large degree on the accuracy of it's preceding rung.  So, if our radar ranging data of the planets is out, this will then skew all the other rungs, leading to increasingly inaccurate distance measurements for the wider and deeper universe.  

 

The Nature article about unreliable supernovae refers to white dwarf (type 1A) supernovae.

This distance measuring method is used in the 'galactic cluster' rung of the ladder.  For my part, I'm not too worried about this latest news.  For two reasons.  First, in the next decade there's bound to be a major revision of the ladder anyway - due to the data from the Gaia mission.  http://sci.esa.int/gaia/  This will sharpen up the accuracy of the Nearby Stars and Milky Way rungs of the ladder,  leading to corresponding adjustments of the 'higher' rungs.  Second, this is way the way science works.  It constantly seeks to improve itself by adjusting and compensating for new data and new discoveries.  

 

 

 

Thanks,

 

BAA. 

 

 

 

[pantheory]

14 hours ago, LogicalFallacy said:

http://www.nature.com/news/supernova-s-messy-birth-casts-doubt-on-reliability-of-astronomical-yardstick-1.22066

 

A short summary in my own words. The brightness of supernova has until recently been considered fairly standard and a reliable way to measure expansion of the universe. However recent discoveries case doubt on this reliability and throw into doubt the reliability of the data that is used to determine the expansion rate of the universe.

 

The comments section is also interesting. One person stated that there is a problem with the expansion of the universe theory - namely that galaxies are not expanding, but the space between galaxies is. The person thought this was an inconstancy in the theory - why should space between galaxies expand, but space in galaxies not expand? Can any of our more knowledgeable folks shed light?

 

Hmm actually found a blog that might explain that question: http://backreaction.blogspot.co.nz/2017/08/you-dont-expand-just-because-universe.html

 

Essentially they question the reliability of type 1a supernova as being standard candles to measure distances beyond our galaxy. My own model and papers question the validity of the Hubble formula which is used with supernovae 1a data to determine these distances.  I wrote a scientific paper showing calculations why the Hubble distance formula is probably wrong while proposing an alternative formulation that has no need for dark energy. One of the two links below relate to the press release and the other to a scientific paper that a co-author and I have written and published. This paper contains extensive calculations asserting that dark energy probably does not exist as well as questioning that the universe is expanding, and questions the validity of the lambda, cold dark matter model (the Big Bang theory).

 

Scientific papers that I have written concerning dark energy relate more to calculation inconsistencies of the standard model than to the reliability of type 1a supernovae as standard candles.

.

Here are the links relating to the press release and paper proposing that dark energy probably does not exist.

 

https://www.send2press.com/wire/a-new-research-study-has-concluded-that-dark-energy-probably-does-not-exist_2014-03-0307-001

http://www.ccsenet.org/journal/index.php/apr/article/view/32603

 

 

 

 

[bornagainathiest]

11 hours ago, LogicalFallacy said:

http://www.nature.com/news/supernova-s-messy-birth-casts-doubt-on-reliability-of-astronomical-yardstick-1.22066

 

A short summary in my own words. The brightness of supernova has until recently been considered fairly standard and a reliable way to measure expansion of the universe. However recent discoveries case doubt on this reliability and throw into doubt the reliability of the data that is used to determine the expansion rate of the universe.

 

The comments section is also interesting. One person stated that there is a problem with the expansion of the universe theory - namely that galaxies are not expanding, but the space between galaxies is. The person thought this was an inconstancy in the theory - why should space between galaxies expand, but space in galaxies not expand? Can any of our more knowledgeable folks shed light?

 

Hmm actually found a blog that might explain that question: http://backreaction.blogspot.co.nz/2017/08/you-dont-expand-just-because-universe.html

 

I defer to Sabine (Backreaction) Hossenfelder's in-depth knowledge of these matters.

 

My own understanding of what is expanding and what isn't hinges on one word - scale.

On the largest scales (the voids between galactic clusters and super-clusters) dark energy overcomes gravity and causes the fabric of space to expand.  On smaller scales (inside galaxies and galactic clusters) gravity wins out and prevents space within these regions from expanding.  Therefore, objects within galaxies and galactic clusters (stars, planets, cheesecakes, etc) do not expand because the space they occupy doesn't expand.  

 

A simple experiment you can do for yourself can help to illuminate this.

Just as the interplay of dark energy and gravity varies over distance, so does the interplay of gravity and electromagnetism.  On small scales the electromagnetic attraction of a hand-held magnet easily overcomes the gravitational pull of the entire Earth.  Over the distance of an inch or so, something weighing less than an ounce can out pull something weighing 5,972,000,000,000,000,000,000 tons.  Yet, when it comes to greater distances and larger scales, gravity's power asserts itself.  Over a distance of about 245,000 miles, the gravitational 'pull' of the Earth keeps the Moon in a stable orbit.   

 

So, it really is just a matter of which scale you're looking at.

 

Thanks,

 

BAA.