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Lower Manhattan, or “all the way downtown” in the parlance of New Yorkers emphatically giving directions to tourists, has long been wher... -
The swollen Adelaide River snakes through Arnhem Land, Northern Territory, Australia. Arnhem Land is a vast wilderness rich in the cu...
mercredi 27 avril 2016
mercredi 20 avril 2016
Earth Day by Natgeo
natgeo Photo coryrichards To me, celebrating Earth Day means reminding myself that we are a part of this planet, and not apart from it. We need it, but it does not need us in the strictest terms. Everest is our planet's biggest and most iconic mountain...a physical and metaphorical canvas on which we place ideas and dreams. It is at once symbolic of the planets great power and indifference, and our own fragility. Celebrating this week in its shadow reminds me to tread lightly as this balance is a delicate one. You can follow the day to day of the expedition on Snapchat at EverestNoFilter
The River snakes
The swollen Adelaide River snakes through Arnhem Land, Northern Territory, Australia. Arnhem Land is a vast wilderness rich in the culture of the Yolngu, indigenous people, who have occupied the land for over 60,000 years.
dimanche 17 avril 2016
Banff National Park
The Banff National Park is Canada's oldest national park, established in 1885 in the Rocky Mountains. The park, located 110–180 kilometres (68–112 mi) west of Calgary in the province of Alberta, encompasses 6,641 square kilometres (2,564 sq mi) of mountainous terrain, with numerous glaciers and ice fields, dense coniferous forest, and alpine landscapes. The Icefields Parkway extends from Lake Louise, connecting to Jasper National Park in the north. Provincial forests and Yoho National Park are neighbours to the west, while Kootenay National Park is located to the south and Kananaskis Country to the southeast. The main commercial centre of the park is the town of Banff, in the Bow River
valley.Top Ten Things to Do in Banff National Park
Canada's first national park, Banff is an outdoor playground full of deep, rustic wild lands; hulking, muscular peaks; and vast, glacially sculpted valleys. With so much to do and see throughout the park, it can be difficult prioritizing. While there are dozens of activities to enjoy, some combine easy, scenic tours and challenging backcountry excursions for a true taste of Banff.
Drive the Icefields Parkway
See the scenery and wildlife of Banff from what "National Geographic" calls a "Drive of a Lifetime." The 142-mile Icefields Parkway traces the Continental Divide and connects two national parks, Banff and Jasper, as well as the staple towns of Lake Louise and Jasper. You'll see glaciers, wildlife, iconic mountains, alpine lakes and other breathtaking scenery along the way.
Ski Banff
Banff National Park's three resorts are home to much of Alberta's best skiing. Lake Louise is the second-largest ski resort in Canada with more than 4,000 acres of terrain, and Sunshine Village has some of the most challenging terrain on the continent in areas like Delirium Dive and Wild West. Mount Norquay is one of the oldest resorts in Canada.
Stay at a Backcountry Lodge or Hut
Banff is home to many public and private backcountry lodges. These rustic shelters are located deep in the heart of the wilderness, requiring miles of hiking, cross-country skiing and/or climbing. Once there, you'll enjoy unparalleled views and solitude. Options include the Skoki Lodge (skokilodge.com) and the Alpine Club of Canada (alpineclubofcanada.ca) huts.
Sip the Most Scenic Cup of Tea of Your Life
Deep within the confines of Banff wilderness, you'll find several alpine tea houses open only during summer. The only way to get to these hidden gems is by foot, horseback or helicopter. From the Fairmont Chateau Lake Louise (fairmontlakelouise.com), hike the two miles to the Lake Agnes Tea House. If you have the ambition, continue another one and a half miles or so to the Plain of Six Glaciers Tea House.
Ride the Banff Gondola
The eight-minute ride to the top of 7,500-foot Sulphur Mountain provides panoramic views of the park. You can access the gondola directly from the gateway town of Banff, making it a quick, pain-free adventure.
Roll Onto the Columbia Icefields
The Columbia Icefield Glacier Experience just off the Icefields Parkway takes you right onto the icefield in large, six-wheeled, all-terrain vehicles. There aren't many places where you'll experience something similar.
Gape at the Hoodoos
More commonly associated with the deserts of the U.S. Southwest, hoodoos are rock features carved by wind and elements into tall, spire-like structures. Banff offers the opportunity to view alpine hoodoos just two and a half miles from town. You can hike to the hoodoos or float past them on the Bow River.
Watch the Reels Roll at the Banff Film Festival
In this adventurous part of the world, even movies are served with an adrenaline-draining twist. The Banff Mountain Film Festival is perhaps the premier mountain and adventure-sport film festival in the world. It begins in the town of Banff each fall before traveling to cities and mountain towns around the world.Backpack Banff
Banff's expansive depths can be truly explored only over the course of days, weeks or months. Backpacking offers a way of seeing even the most distant reaches of the park. With 50 backcountry campsites and a variety of shelters and lodges, Banff has a solid infrastructure to support your voyage. You'll need to understand the dangers of the park and get a backcountry permit to begin your adventure.
Unwind in Nature's Hot Tub
No matter what you do beforehand, unwind at the end of the day/trip in one of the hot springs around Banff National Park. Upper Banff Springs is run by Parks Canada and offers an outdoor spring-fed pool with views of Mount Rundle.
Where to stay in Banff
If you come into Banff along Banff Avenue you’ll pass 13 hotels in just six blocks. There ‘s plenty of choice across the full budget spectrum. Plus there is nearby camping at Tunnel Mountain once the snow disappears.
samedi 16 avril 2016
Gravitational waves
Waves of gravity turn up a century after Albert Einstein predicted them
Two black holes circle one another.
Both are about 100km across. One con-
tains 36 times as much mass as the sun; the
other, 29. They are locked in an orbital
dance, a kilometre or so apart, that is accelerating rapidly to within a whisker of the
speed of light. Their event horizons—the
spheres defining their points-of-no-return—touch. There is a violent wobble as,
for an instant, quintillions upon quintil-
lions of kilograms redistribute themselves.
Then there is calm. In under a second, a
larger black hole has been born.
It is, however, a hole that is less than the
sum of its parts. Three suns’ worth of mass
has been turned into energy, in the form of
gravitational waves: travelling ripples that
stretch and compress space, and thereby
all in their path. During the merger’s final
fifth of a second, envisaged in an artist’s
impression above, the coalescing holes
pumped 50 times more energy into space
this way than the whole of the rest of the
universe emitted in light, radio waves, X-
rays and gamma rays combined.
And then, 1.3 billion years later, in September 2015, on a small planet orbiting an
unregarded yellow sun, at facilities known
to the planet’s inhabitants as the Advanced
Laser Interferometer Gravitational-wave
Observatory (LIGO), the faintest slice of
those waves was caught. That slice, called
GW150914 by LIGO’s masters and announced to the world on February 11th, is
the first gravitational wave to be detected
directly by human scientists. It is a triumph
that has been a century in the making,
opening a new window onto the universe
and giving researchers a means to peer at
hitherto inaccessible happenings, perhaps
as far back in time as the Big Bang.
Finger on the pulsar
The idea of gravitational waves emerged
from the general theory of relativity, Albert
Einstein’s fundamental exposition of gravity, unveiled almost exactly 100 years before GW150914’s discovery. Mass, Einstein
realised, deforms the space and time
around itself. Gravity is the effect of this,
the behaviour of objects dutifully moving
along the curves of mass-warped space-
time. It is a simple idea, but the equations
that give it mathematical heft are damnably hard to solve. Only by making certain
approximations can solutions be found.
And one such approximation led Einstein
to an odd prediction: any accelerating
mass should make ripples in spacetime.
Einstein was not happy with this idea. He would, himself, oscillate like a wave on the topic—rescinding and remaking his case, arguing for such waves and then, after redoing the sums, against them. But, while he and others stretched and squeezed the maths, experimentalists set bout trying to catch the putative waves in the act of stretching and squeezing matter.
Einstein was not happy with this idea. He would, himself, oscillate like a wave on the topic—rescinding and remaking his case, arguing for such waves and then, after redoing the sums, against them. But, while he and others stretched and squeezed the maths, experimentalists set bout trying to catch the putative waves in the act of stretching and squeezing matter.
Their problem was that the expected ef-
fect was a transient change in dimensions
equivalent to perhaps a thousandth of the
width of a proton in an apparatus several
kilometres across. Indirect proof of gravita-
tional waves’ existence has been found
over the years, most notably by measuring
radio emissions from pairs of dead stars
called pulsars that are orbiting one anoth-
er, and deducing from this how the dis-
tance between them is shrinking as they
broadcast gravitational waves into the cos-
mos. But the waves themselves proved elu-
sive until the construction of LIGO.
As its name states, LIGO is an interfer- ometer. It works by splitting a laser beam in two, sending the halves to and fro along paths identical in length but set at right an- gles to one another, and then looking for interference patterns when the halves are recombined (see diagram overleaf). If the half-beams’ paths are undisturbed, the waves will arrive at the detector in lock- step. But a passing gravitational wave will alternately stretch and compress the half- beams’ paths. Those half-beams, now out of step, will then interfere with each other at the detector in a way that tells of their ex- perience. The shape of the resulting inter- ference pattern contains all manner of in- formation about the wave’s source, including what masses were involved and how far away it was.
To make absolutely certain that what is seen really is a gravitational wave requires taking great care. First, LIGO is actually two facilities, one in Louisiana and the other in Washington state. Only something which is observed almost, but not quite, simulta- neously by both could possibly be a gravi- tational wave. Secondly, nearly everything in the interferometers’ arms is delicately suspended to isolate it as far as possible from distant seismic rumblings and the vi- brations of passing traffic.
As its name states, LIGO is an interfer- ometer. It works by splitting a laser beam in two, sending the halves to and fro along paths identical in length but set at right an- gles to one another, and then looking for interference patterns when the halves are recombined (see diagram overleaf). If the half-beams’ paths are undisturbed, the waves will arrive at the detector in lock- step. But a passing gravitational wave will alternately stretch and compress the half- beams’ paths. Those half-beams, now out of step, will then interfere with each other at the detector in a way that tells of their ex- perience. The shape of the resulting inter- ference pattern contains all manner of in- formation about the wave’s source, including what masses were involved and how far away it was.
To make absolutely certain that what is seen really is a gravitational wave requires taking great care. First, LIGO is actually two facilities, one in Louisiana and the other in Washington state. Only something which is observed almost, but not quite, simulta- neously by both could possibly be a gravi- tational wave. Secondly, nearly everything in the interferometers’ arms is delicately suspended to isolate it as far as possible from distant seismic rumblings and the vi- brations of passing traffic.
Moreover, in order to achieve the re-
quired sensitivity, each arm of each inter-
ferometer is 4km long and the half-beam in
it is bounced 100 times between the mir-
rors at either end of the arm, to amplify any
discrepancy when the half-beams are re-
combined. Even so, between 2002 when
LIGO opened and 2010, when it was closed
for upgrades, nary a wave was seen.
Holey moly
Those improvements, including doubling the bulk of the devices’ mirrors, suspend- ing them yet more delicately, and increas- ing the laser power by a factor of 75, have made Advanced LIGO, as the revamped apparatus is known, four times as sensitive as the previous incarnation. That extra sen- sitivity paid off almost immediately. In- deed, the system’s operators were still kick- ing its metaphorical tyres and had yet to begin its official first run when GW150914 turned up, first at the Louisiana site, and about a hundredth of a second later in Washington—a difference which places the outburst somewhere in the sky’s southern hemisphere. Since then, the team have been checking their sums and counting their lucky stars. As they outline in Physical Review Letters, the likelihood that the sig- nal was a fluke is infinitesimal.
When one result comes so quickly, oth- ers seem sure to follow—particularly as the four months of data the experiment went on to gather as part of the first official run have yet to be analysed fully. A rough esti- mate suggests one or two other signals as striking as GW150914 may lie within them.
For gravitational astronomy, this is just the beginning. Soon, LIGO will not be alone. By the end of the year VIRGO, a gravitational wave observatory in Italy, should join it in its search. Another is under construction in Japan and talks are under way to create a fourth, in India. Most ambitiously, a fifth, orbiting, observatory, the Evolved Laser Interferometer Space Antenna, or e- LISA, is on the cards. The first pieces of apparatus designed to test the idea of e-LISA are already in space.
Holey moly
Those improvements, including doubling the bulk of the devices’ mirrors, suspend- ing them yet more delicately, and increas- ing the laser power by a factor of 75, have made Advanced LIGO, as the revamped apparatus is known, four times as sensitive as the previous incarnation. That extra sen- sitivity paid off almost immediately. In- deed, the system’s operators were still kick- ing its metaphorical tyres and had yet to begin its official first run when GW150914 turned up, first at the Louisiana site, and about a hundredth of a second later in Washington—a difference which places the outburst somewhere in the sky’s southern hemisphere. Since then, the team have been checking their sums and counting their lucky stars. As they outline in Physical Review Letters, the likelihood that the sig- nal was a fluke is infinitesimal.
When one result comes so quickly, oth- ers seem sure to follow—particularly as the four months of data the experiment went on to gather as part of the first official run have yet to be analysed fully. A rough esti- mate suggests one or two other signals as striking as GW150914 may lie within them.
For gravitational astronomy, this is just the beginning. Soon, LIGO will not be alone. By the end of the year VIRGO, a gravitational wave observatory in Italy, should join it in its search. Another is under construction in Japan and talks are under way to create a fourth, in India. Most ambitiously, a fifth, orbiting, observatory, the Evolved Laser Interferometer Space Antenna, or e- LISA, is on the cards. The first pieces of apparatus designed to test the idea of e-LISA are already in space.
Together, by jointly forming a telescope
that will permit astronomers to pinpoint
whence the waves come, these devices
will open a new vista on the universe. As
technology improves, waves of lower fre-
quency—corresponding to events involv-
ing larger masses—will become detectable.
Eventually, astronomers should be able to
peer at the first 380,000 years after the Big
Bang, an epoch of history that remains in-
accessible to every other kind of telescope
yet designed.
The real prize, though, lies in proving Einstein wrong. For all its prescience, the theory of relativity is known to be incom- plete because it is inconsistent with the other great 20th-century theory of physics, quantum mechanics. Many physicists sus- pect that it is in places where conditions are most extreme—the very places which launch gravitational waves—that the first chinks in relativity’s armour will be found, and with them a glimpse of a more all embracing theory.
Gravitational waves, of which Einstein remained so uncertain, have provided di- rect evidence for black holes, about which he was long uncomfortable, and may yet yield a peek at the Big Bang, an event he knew his theory was inadequate to de- scribe. They may now lead to his theory’s unseating. If so, its epitaph will be that in predicting gravitational waves, it predicted the means of its own demise.
The real prize, though, lies in proving Einstein wrong. For all its prescience, the theory of relativity is known to be incom- plete because it is inconsistent with the other great 20th-century theory of physics, quantum mechanics. Many physicists sus- pect that it is in places where conditions are most extreme—the very places which launch gravitational waves—that the first chinks in relativity’s armour will be found, and with them a glimpse of a more all embracing theory.
Gravitational waves, of which Einstein remained so uncertain, have provided di- rect evidence for black holes, about which he was long uncomfortable, and may yet yield a peek at the Big Bang, an event he knew his theory was inadequate to de- scribe. They may now lead to his theory’s unseating. If so, its epitaph will be that in predicting gravitational waves, it predicted the means of its own demise.
samedi 9 avril 2016
lundi 4 avril 2016
dimanche 3 avril 2016
Les plus de Madère
L’île aux fleurs
La grande « spécialité » du lieu ! Si la France devait être un fromage, Madère serait sans doute une fleur. On la décrit souvent comme un « jardin flottant », et la comparaison n’est pas surfaite : il suffit de compter le nombre de jardins botaniques ouverts au public pour s’en rendre compte. Partout, le long des routes, dans les quintas fastueuses ou dans les vergers de simples maisons, c’est un bouquet de couleurs chatoyantes où abondent magnolias, agapanthes, amaryllis ou hortensias, hibiscus, géraniums, bégonias, bougain- villées, oiseaux de paradis... Une impor- tante culture d’orchidées s’y est aussi développée. A voir pour le croire...
Une végétation unique
La merveille de Madère. L’île est un véritable « métissage végétal » : zone subtropicale où s’étalent les cultures de bananes, de cannes à sucre ; zone tempérée chaude de type méditerra- néenne, qui a encouragé les cultures de la vigne et des céréales comme le maïs, le blé ou l’avoine, et surtout des fruits tropicaux à volonté, toujours délicieux, et tellement exotiques ; et domaine de la forêt primitive (forêt aurifère), vestige unique au monde de l’ère tertiaire avant la grande période de glaciation.
Découvertes » est important :
églises, palais, ou quintas délicieuses.
Très fameux chez nos amis d’outre-
Manche, ces vins (il y a plusieurs
variétés) ne se sont pas encore fait
une place au soleil dans nos menus
ou dans nos soirées francophones.
Certains les confondent même avec le
porto ! Mais à l’apéritif ou au dessert,
voire durant le repas pour quelques
nectars, on peut se laisser tenter
sans crainte : il y a fort à parier que
quelques bouteilles feront même le
voyage retour dans vos valises !
Pays
La merveille de Madère. L’île est un véritable « métissage végétal » : zone subtropicale où s’étalent les cultures de bananes, de cannes à sucre ; zone tempérée chaude de type méditerra- néenne, qui a encouragé les cultures de la vigne et des céréales comme le maïs, le blé ou l’avoine, et surtout des fruits tropicaux à volonté, toujours délicieux, et tellement exotiques ; et domaine de la forêt primitive (forêt aurifère), vestige unique au monde de l’ère tertiaire avant la grande période de glaciation.
Une culture riche
et vivante
L’héritage des « Grandes
et vivante
L’héritage des « Grandes
Quelques musées méritent le détour
pour mieux comprendre les traditions
de cette petite enclave atlantique.
Ces dernières sont d’ailleurs toujours
vivaces, on ne compte plus les fêtes
qui animent tel ou tel village au cours
de l’année, et les ateliers de broderie
ou de vannerie témoignent que l’arti-
sanat madérien n’est pas seulement
un argument touristique mais encore
une réalité.
Des paysages fascinants
L’île est constituée d’une chaîne montagneuse plongeant dans la mer à plus de 3 000 m de profondeur. Elle offre au regard un paysage sauvage et irrégulier, façonné par l’érosion et la houle de la mer au fil des siècles : on ne se lasse pas de cette nature abrupte et laborieuse, de ces petits vallons verdoyants bucoliques, et de ces pics farouches, dominant les nuages.
Des vins à découvrir
Des paysages fascinants
L’île est constituée d’une chaîne montagneuse plongeant dans la mer à plus de 3 000 m de profondeur. Elle offre au regard un paysage sauvage et irrégulier, façonné par l’érosion et la houle de la mer au fil des siècles : on ne se lasse pas de cette nature abrupte et laborieuse, de ces petits vallons verdoyants bucoliques, et de ces pics farouches, dominant les nuages.
Des vins à découvrir
* Nom officiel : région autonome
de Madère.
* Capitale : Funchal (111 892 habitants).
* Superficie : 801,77 km2, dont 727 km2 environ pour l’île de Madère.
* Langues : Portugais. Population
* Nombre d’habitants : 270 100 (2014).
* Densité : 337 hab./km2.
* Capitale : Funchal (111 892 habitants).
* Superficie : 801,77 km2, dont 727 km2 environ pour l’île de Madère.
* Langues : Portugais. Population
* Nombre d’habitants : 270 100 (2014).
* Densité : 337 hab./km2.
* Taux de natalité : 9,76 ‰.
* Taux de mortalité : 10,86 ‰.* Espérance de vie : 78 ans.* Taux d’alphabétisation : 93,2 %.
* Religion : catholique.
Économie
* Monnaie : l’euro.* PIB:4,8milliardsd’euros(2014). w PIB/habitant : 18 775 E/hab.
*
PIB/secteur : agriculture 3 %,
industrie 10 %, services 87 % (dont
un quart pour le tourisme).
* Taux de mortalité : 10,86 ‰.* Espérance de vie : 78 ans.* Taux d’alphabétisation : 93,2 %.
* Religion : catholique.
Économie
* Monnaie : l’euro.* PIB:4,8milliardsd’euros(2014). w PIB/habitant : 18 775 E/hab.
*
* Taux de croissance : 1 %.
* Taux de chômage : 17,2 %.
* Taux d’inflation : +5 %.
Décalage horaire
Toute l’année, quand il est midi à Paris, il est 11h à Funchal. En accord avec les lois de l’Union européenne, on avance d’une heure le dernier dimanche de mars, et on recule d’une heure le dernier dimanche d’octobre.
* Taux de chômage : 17,2 %.
* Taux d’inflation : +5 %.
Décalage horaire
Toute l’année, quand il est midi à Paris, il est 11h à Funchal. En accord avec les lois de l’Union européenne, on avance d’une heure le dernier dimanche de mars, et on recule d’une heure le dernier dimanche d’octobre.
Climat
* Tempéré.Lestempératuresvarient entre 17 °C en hiver et 23 °C en été.
* La température de l’eau est sensiblement la même tout au long de l’année grâce au courant chaud du Gulf Stream (entre 18 et 22 °C environ).
* Tempéré.Lestempératuresvarient entre 17 °C en hiver et 23 °C en été.
* La température de l’eau est sensiblement la même tout au long de l’année grâce au courant chaud du Gulf Stream (entre 18 et 22 °C environ).
vendredi 1 avril 2016
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Lower Manhattan, or “all the way downtown” in the parlance of New Yorkers emphatically giving directions to tourists, has long been wher...
-
The swollen Adelaide River snakes through Arnhem Land, Northern Territory, Australia. Arnhem Land is a vast wilderness rich in the cu...