Search Results - Google+

Post has shared content

Public

Originally shared by Eli Fennell - 3 comments

14-Year Clock Observation Finds No Evidence of Physical Laws Changing
But They Still Might, Anyways

One of the foundational assumptions of cosmology is that the laws of physics are related with certain constants, things which were true yesterday and today and will be true tomorrow, and are true here, over there, or anywhere.

The gravitational constant on Earth, the Moon, Mars, Jupiter, our Sun, distant stars, exoplanets, and black holes is the same (save maybe on the other side of a purely theoretical Event Horizon). Ditto any of the other basic laws. Without this being true, we could not assume an observation of a distant thing was valid by comparing it with the laws known to operate here, nor could we assume the laws operating a million years ago were the same as now or will be the same a million years hence. This is so central to cosmology, and Physics writ large, that it has become in many ways the Quod Semper, Quod Ubique, Quod Ab Omnibus of modern science.

It's not simply that we feel we must be able to make such an assumption to protect our intellectual endeavors from any doubt of their validity, either: it's that evidence of the inconstancy of these laws is in short supply, while evidence of their constancy is seemingly abundant in the sciences and natural world.

New research from the National Institute of Standards and Technology (NIST; United States) has now contributed additional evidence for physical constancy, after spending 14-years meticulously measuring the activity of atomic clocks. Since these clocks are extremely precise and immune to almost any influence beyond a change in the physical laws governing their radioactive properties, especially when measures are taken across many such clocks, these make ideal tools for searching for any such physical changes, such as changes to the relativistic forces between Earth and Sun as the former orbits the latter.

The clocks held firm, refusing to change more than would be expected assuming a constancy of physical laws. While this further justifies our confidence in the basic principle of constancy as a valid yardstick for measuring phenomenon and deriving theories, it does not mean that the constants of physics have now proven to be well and fully constant.

It may be, rather, that any inconstancy remains at too fine or too great a scale for our measurements. We may lack precision for very small variations to be noticed. Or, our periods of measurement in time, or the space in which we measure them, may not be sufficiently large to see effects which occur at very large cosmological scales. A 2010 study (http://bit.ly/2LHqVkI), for example, suggested that the Alpha or Fine-Structure constant may vary slightly across the visible universe or even over time, such that a 14-year observation of atomic clocks in one tiny corner of that universe would likely be insufficient to discern it, though the ramifications for cosmology if true would remain enormous.

What this, again, does do is provides reassurance that the laws of physics are not like "th' inconstant moon" Shakespeare's Juliet warned Romeo against swearing by for her. If physics does change across time and space, it is doing so in the backgrounds and gaps of our current theories, at such scales that we need not fret too much about it unless we be, perhaps, of the mind to explain the origins, development, and destiny of the cosmos, or the fundamental stuff of which the cosmos are composed (whatever that may be).

#BlindMeWithScience #Physics #Cosmology

Scientists Stared at Clocks for 14 Years to Try and Catch the Laws of Physics Changing

popularmechanics.com

Post has attachment

Justin Aptaker

Cosmology, SETI, Origin of Life

Astronomers Have Found the Universe's Missing Matter | WIRED ~

Dark #matter on the other hand, is still an enigma.

#astrophysics #cosmology #astronomy #Physics #Cosmos #Space #Science #Universe

Astronomers Have Found the Universe's Missing Matter | WIRED

wired.com

Post has shared content

Maria Varney

Public

Originally shared by Steven Spence - 12 comments

String Theory Inconsistent With Dark Energy and Big Bang?

But now, Vafa and his colleagues were conjecturing that in the string landscape, universes like ours — or what ours is thought to be like — don’t exist. If the conjecture is correct, Wrase and other string theorists immediately realized, the cosmos must either be profoundly different than previously supposed or string theory must be wrong.
...
The conjectured formula — posed in the June 25 paper by Vafa, Georges Obied, Hirosi Ooguri and Lev Spodyneiko and further explored in a second paper released two days later by Vafa, Obied, Prateek Agrawal and Paul Steinhardt — says, simply, that as the universe expands, the density of energy in the vacuum of empty space must decrease faster than a certain rate. The rule appears to be true in all simple string theory-based models of universes. But it violates two widespread beliefs about the actual universe: It deems impossible both the accepted picture of the universe’s present-day expansion and the leading model of its explosive birth.

#science #cosmology #stringtheory #darkenergy #string #bigbang #inflation

Dark Energy May Be Incompatible With String Theory | Quanta Magazine