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Posts Tagged ‘gravity

“Time is the longest distance between two places”*…


In quantum mechanics, time is universal and absolute; its steady ticks dictate the evolving entanglements between particles. But in general relativity (Albert Einstein’s theory of gravity), time is relative and dynamical, a dimension that’s inextricably interwoven with directions x, y and z into a four-dimensional “space-time” fabric. The fabric warps under the weight of matter, causing nearby stuff to fall toward it (this is gravity), and slowing the passage of time relative to clocks far away. Or hop in a rocket and use fuel rather than gravity to accelerate through space, and time dilates; you age less than someone who stayed at home.

Unifying quantum mechanics and general relativity requires reconciling their absolute and relative notions of time. Recently, a promising burst of research on quantum gravity has provided an outline of what the reconciliation might look like — as well as insights on the true nature of time…

The effort to unify quantum mechanics and general relativity means reconciling totally different notions of time; catch up on the state of play at “Quantum Gravity’s Time Problem.”

* Tennessee Williams, The Glass Menagerie


As we set our watches, we might send carefully-calculated birthday greetings to Gabrielle-Émilie Le Tonnelier de Breteuil, Marquise du Châtelet, the French mathematician and physicist who is probably (if unfairly) better known as Voltaire’s mistress; she was born on this date in 1706.  Fascinated by the work of Newton and Leibniz, she dressed as a man to frequent the cafes where the scientific discussions of the time were held.  Her major work was a translation of Newton’s Principia, for which Voltaire wrote the preface; it was published a decade after her death, and was for many years the only translation of the Principia into French.

Judge me for my own merits, or lack of them, but do not look upon me as a mere appendage to this great general or that great scholar, this star that shines at the court of France or that famed author. I am in my own right a whole person, responsible to myself alone for all that I am, all that I say, all that I do. it may be that there are metaphysicians and philosophers whose learning is greater than mine, although I have not met them. Yet, they are but frail humans, too, and have their faults; so, when I add the sum total of my graces, I confess I am inferior to no one.
– Mme du Châtelet to Frederick the Great of Prussia


Written by LW

December 17, 2016 at 1:01 am

Obsessed with his weight…

German scale-maker Kern has been in the weighing business since 1844.  To demonstrate the precision of the scientific instruments in which it now specializes, Kern has launched The Gnome Experiment.

If Earth was a perfect sphere of uniform density, then gravity would be consistent. But it’s not, which means gravity varies wherever you go. So can we chart those discrepancies using just a basic-range Kern scale?


We’re shipping our Gnome Kit from scientist to scientist around the world. Join the experiment and you’ll receive:

1x Kern EWB 2.4 Scale
Pre-calibrated according to local gravity at Kern HQ, Balingen, Germany.

1x Kern Gnome
The perfect test-subject for two good reasons: Gnomes are already accustomed to travelling the world. They also originate from our homeland, Germany.

1x Lab gloves & 1 x Air duster
Important because dust or grease will reduce the accuracy of the results.

Readers can check up on results-to-date…

… and can sign up to participate, here.


As we pack our bags to move south,* we might send earthy birthday greetings to civil engineer and geodesist John Fillmore Hayford; he was born on this date in 1868.  Hayford, the father of the modern science of geodesy, made the first precise determination of the ellipsoidal shape and size of the earth.


* an object weighs about 0.5% more at the poles than at the Equator.

Written by LW

May 19, 2012 at 1:01 am

A Matter of Some Gravity…


I’ve been noticing gravity since I was very young.
-Cameron Diaz

Isaac Newton first proposed a universal law of gravitation, where every massive body in the universe was attracted to every other one. This simple law proved extremely powerful, able to explain the orbits of planets and the reason the apocryphal apple fell on his head. However, Newton was never able to explain why gravity worked or what exactly it was. Two hundred plus years later, Albert Einstein was able to offer a more complete description of gravity—one where Newton’s laws are a limited case. According to Einstein, gravity was due to the warpage of spacetime by mass and energy; all objects followed straight paths, just on curved spaces.

With the advent of quantum theory over the past 100 years, scientists have been able to develop an elegant mathematical framework capable of uniting three of the four fundamental forces that are thought to exist in the universe. The fourth, gravity, still remains the fly in the ointment, and has resisted unification to this point. Early last year, Dutch theoretical physicist Erik Verlinde published a manuscript to the arXiv that purports to explain why science cannot reconcile all four fundamental forces. According to him, it is simple: “gravity doesn’t exist.”

Read the full story (SPOILER ALERT: it relates to Leonard Susskind‘s “holographic principle,” suggesting in effect that gravity isn’t a fundamental force, but an “entropic” result of information imbalances between the bodies/regions in question) in Ars Technica (recapping Physical Review D, 2011. DOI: 10.1103/PhysRevD.83.021502).

As we sit more confidently beneath apple trees, we might wish a polymathic Happy Birthday to the painter, sculptor, architect, musician, scientist, mathematician, engineer, inventor, anatomist, geologist, cartographer, botanist and writer– the archetypical Renaissance Man– Leonardo da Vinci; he was born on this date in 1452.

Self-portrait in Red Chalk (source)

G Whiz…

In Rio, at the 2016 Olympics, the same jump will get an athlete >1 cm higher than that jump at the London Olympics in 2012…

From the ever-illuminating xkcd.

As we rethink our choice of venue, we might wish a humorously absurd Happy Birthday to Terry Jones, author, screenwriter, director, actor, television host– and most famously, founding member of Monty Python.  He was born on this date in 1942.  Among his many awards, “9622 Terryjones,” an asteroid in the main belt between Mars and Jupiter, was named in his honor.


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