Search This Blog

Wednesday, March 18, 2015

Siberia


From Wikipedia, the free encyclopedia
Coordinates: 60°0′N 105°0′E / 60.000°N 105.000°E / 60.000; 105.000


       Siberian Federal District

       Geographic Russian Siberia

       Siberia according to widest definition and in historical use

Siberia (/sˈbɪəriə/; Russian: Сиби́рь, tr. Sibir'; IPA: [sʲɪˈbʲirʲ]) is an extensive geographical region, and by the broadest definition is also known as North Asia. Siberia has been historically part of Russia since the seventeenth century.

The territory of Siberia extends eastwards from the Ural Mountains to the watershed between the Pacific and Arctic drainage basins. Siberia stretches southwards from the Arctic Ocean to the hills of north-central Kazakhstan and to the national borders of Mongolia and China.[1] Siberia accounts for 77% of Russia's land area (13.1 million square kilometres), but is home to just 27% (40 million people) of the country's population.

Etymology

Some sources say that "Siberia" originates from the Siberian Tatar word for "sleeping land" (Sib Ir).[2] Another version is that this name was the ancient tribal name of the Sipyrs, a mysterious people, later assimilated to Siberian Tatars. The modern usage of the name appeared in the Russian language after the conquest of the Siberian Khanate. A further variant claims that the region was named after the Xibe people.[3] The explanation that the name is derived from the Russian word for "north" (север, sever) has been put forward by the Polish historian Chycliczkowski,[4] but this explanation has been dismissed by Anatole Baikaloff[5] on the grounds that the neighbouring Chinese, Arabs and Mongolians (whose name for the region is similar) could not have known Russian. His own suggestion is that the name is a combination of two words, "su" (water) and "bir" (wild land).

History

The tower of a 17th-century ostrog fort, in Yakutsk.

The Siberian Traps were formed by one of the largest known volcanic events of the last 500 million years of Earth's geological history. These continued for a million years and are considered the likely cause of the "Great Dying" about 250 million years ago,[6] which is estimated to have killed 90% of species existing at the time.[7]

At least three species of humans lived in Southern Siberia around 40,000 years ago: H. sapiens, H. neanderthalensis, and the Denisova hominin (originally nicknamed "Woman X").[8] The last was determined in 2010 by DNA evidence to be a new species.

Siberia was inhabited by different groups of nomads such as the Yenets, the Nenets, the Huns, the Scythians and the Uyghurs. The Khan of Sibir[citation needed] in the vicinity of modern Tobolsk was known as a prominent figure who endorsed Kubrat as Khagan in Avaria in 630. The Mongols conquered a large part of this area early in the 13th century. With the breakup of the Golden Horde, the autonomous Siberia Khanate was established in the late 15th century. Turkic-speaking Yakuts migrated north from the Lake Baikal region under pressure from the Mongol tribes during the 13th to 15th century.[9] Siberia remained a sparsely populated area. Historian John F. Richards wrote: "... it is doubtful that the total early modern Siberian population exceeded 300,000 persons."[10]

Convicts and guards on the road to Siberia, 1845

The growing power of Russia in the West began to undermine the Siberian Khanate in the 16th century. First, groups of traders and Cossacks began to enter the area, and then the Russian army began to set up forts further and further East. Towns such as Mangazeya, Tara, Yeniseysk and Tobolsk were developed, the last being declared the capital of Siberia. At this time, Sibir was the name of a fortress at Qashlik, near Tobolsk. Gerardus Mercator in a map published in 1595 marks Sibier both as the name of a settlement and of the surrounding territory along a left tributary of the Ob.[11] Other sources contend that the Xibe, an indigenous Tungusic people, offered fierce resistance to Russian expansion beyond the Urals, and that Siberia is a Russification of their ethnonym.

By the mid-17th century, areas controlled by Russia had been extended to the Pacific. There were some 230,000 Russians in Siberia by 1709.[12]

Siberian Cossack family in Novosibirsk.

The first great modern change in Siberia was the Trans-Siberian Railway, constructed during 1891–1916. It linked Siberia more closely to the rapidly industrialising Russia of Nicholas II. Around seven million people moved to Siberia from European Russia between 1801 and 1914.[13] From 1859 to 1917, over half a million people migrated to the Russian Far East.[14] Siberia has extensive natural resources. During the 20th century, large-scale exploitation of these was developed, and industrial towns cropped up throughout the region.[15]

At 7:15am on 30 June 1908, millions of trees were felled near the Podkamennaya Tunguska (Stony Tunguska) River in central Siberia in the Tunguska Event, which most scientists believe to have been the air burst of a meteoroid or a comet. Even though no crater has ever been found, the landscape in the (uninhabited) area still bears the scars of this event.

In the early decades of the Soviet Union (especially the 1930s and 1940s), the earlier katorga system of penal labour camps was replaced by a new one that was controlled by the GULAG state agency.[16] According to semi-official Soviet estimates that were not made public in Soviet times, from 1929 to 1953 more than 14 million people passed through these camps and prisons, many of which were in Siberia. A further seven to eight million were internally deported to remote areas of the Soviet Union (including entire nationalities in several cases).[17] 516,841 prisoners died in camps from 1941 to 1943[18] due to food shortages caused by World War II. At other periods, mortality was comparatively lower.[19] The size, scope, and scale of the GULAG slave labour camp remains a subject of much research and debate. Many Gulag camps were positioned in extremely remote areas of northeastern Siberia. The best known clusters are Sevvostlag (The North-East Camps) along the Kolyma River and Norillag near Norilsk, where 69,000 prisoners were kept in 1952.[20] Major industrial cities of Northern Siberia, such as Norilsk and Magadan, were originally camps built by prisoners and run by ex-prisoners.[21]

Geography


Altai, Lake Kutsherla in the Altai Mountains.

The peninsula of Svyatoy Nos, Lake Baikal

Siberian taiga

With an area of 13.1 million km² (5.1 million square miles), Siberia takes up roughly 77% of Russia's total territory. Major geographical zones include the West Siberian Plain and the Central Siberian Plateau. Siberia covers almost 10% of Earth's land surface (148,940,000 km²). While Siberia falls entirely within Asia, many authorities such as the UN geoscheme will not subdivide countries and will place all of Russia as part of Europe and/or Eastern Europe.

Eastern and central Sakha comprise numerous North-South mountain ranges of various ages. These mountains extend up to almost three thousand meters in elevation, but above a few hundred meters they are almost completely devoid of vegetation. The Verkhoyansk Range was extensively glaciated in the Pleistocene, but the climate was too dry for glaciation to extend to low elevations. At these low elevations are numerous valleys, many of them deep, and covered with larch forest, except in the extreme North, where the tundra dominates. Soils are mainly turbels (a type of gelisol). The active layer tends to be less than one meter deep, except near rivers.

The highest point in Siberia is the active volcano Klyuchevskaya Sopka, on the Kamchatka Peninsula. Its peak is at 4,649 meters (15,253 ft).

Mountain ranges

Lakes and rivers

Grasslands

Geology

The West Siberian Plain consists mostly of Cenozoic alluvial deposits and is somewhat flat. Many deposits on this plain result from ice dams. The flow of the Ob and Yenisei Rivers was reversed, so they were redirected into the Caspian Sea (perhaps the Aral as well). The area is very swampy and soils are mostly peaty Histosols and, in the treeless northern part, Histels. In the south of the plain, where permafrost is largely absent, rich grasslands that are an extension of the Kazakh Steppe formed the original vegetation—most of it is not visible anymore.

The Central Siberian Plateau is an extremely ancient craton (sometimes named Angaraland) that formed an independent continent before the Permian (see Siberia (continent)). It is exceptionally rich in minerals, containing large deposits of gold, diamonds, and ores of manganese, lead, zinc, nickel, cobalt and molybdenum. Much of the area includes the Siberian Traps—a large igneous province. The massive eruptive period was approximately coincident with the Permian–Triassic extinction event. The volcanic event is said to be the largest known volcanic eruption in Earth's history. Only the extreme northwest was glaciated during the Quaternary, but almost all is under exceptionally deep permafrost and the only tree that can thrive, despite the warm summers, is the deciduous Siberian Larch (Larix sibirica) with its very shallow roots. Outside the extreme northwest, the taiga is dominant; in fact, taiga covers a significant fraction of the entirety of Siberia.[23] Soils here are mainly Turbels, giving way to Spodosols where the active layer becomes thicker and the ice content lower.

The Lena-Tunguska petroleum province includes the Central Siberian platform (some authors refer to it as the Eastern Siberian platform) bounded on the northeast and east by the Late Carboniferous through Jurassic Verkhoyansk foldbelt, on the northwest by the Paleozoic Taymr foldbelt, and on the southeast, south and southwest by the Middle Silurian to Middle Devonian Baykalian foldbelt.[24] A regional geologic reconnaissance study began in 1932, followed by surface and subsurface mapping, revealed the Markova-Angara Arch (anticlise in Russian), which led to the discovery of the Markovo Oil Field in 1962 with the Markovo 1 well, which produced from the Early Cambrian Osa Horizon bar-sandstone at a depth of 2156 m.[25] The Sredne-Botuobin Gas Field was discovered in 1970, producing from the Osa and the Proterozoic Parfenovo Horizon. [26] The Yaraktin Oil Field was discovered in 1971, producing from Vendian Yaraktin Horizon at depths of up to 1750 m, which lies below Permian to Lower Jurassic basalt traps. [26]

Climate

Russia vegetation.png
     polar desert      tundra      alpine tundra      taiga      montane forest
     temperate broadleaf forest      temperate steppe      dry steppe

Vegetation in Siberia is mostly taiga, with a tundra belt on the northern fringe, and a temperate forest zone in the south.

The climate of Siberia varies dramatically, but all of it basically has short summers and long winters of very cold climate. On the north coast, north of the Arctic Circle, there is a very short (about one-month-long) summer.

Almost all the population lives in the south, along the Trans-Siberian Railway. The climate in this southernmost part is Humid continental climate (Köppen Dfb) with cold winters but fairly warm summers lasting at least four months. Annual average is about 0.5 °C (32.9 °F), January averages about −20 °C (−4 °F) and July about +19 °C (66 °F), while daytime temperatures in summer typically are above 20 °C.[27][28] With a reliable growing season, an abundance of sunshine and exceedingly fertile chernozem soils, southern Siberia is good enough for profitable agriculture, as was proven in the early twentieth century.

By far the most commonly occurring climate in Siberia is continental subarctic (Koppen Dfc or Dwc), with the annual average temperature about −5 °C (23 °F) and roughly −25 °C (−13 °F) average in January and +17 °C (63 °F) in July,[29] although this varies considerably, with July average about 10 °C in the taiga–tundra ecotone. The periodical Weatherwise lists Oymyakon, Republic of Sakha, in Russian Siberia as having one of the 10 worst weathers in the world. It is a village with a population of 500, and it recorded a temperature of −89.9 °F (−67.7 °C) on 6 February 1933. It is considered the Northern Pole of Cold, meaning the coldest known point in the Northern hemisphere. It also frequently reaches 86 °F (30 °C) in the Summer, giving it one of the world's greatest temperature variations.[30]

Southwesterly winds bring warm air from Central Asia and the Middle East. The climate in West Siberia (Omsk, Novosibirsk) is several degrees warmer than in the East (Irkutsk, Chita), where in the north an extreme winter subarctic climate (Köppen Dfd or Dwd) prevails. With the lowest recorded temperature of −71.2 °C (−96.2 °F), Oymyakon (Sakha Republic) has the distinction of being the coldest city on Earth. But summer temperatures in other regions can reach +38 °C (100 °F). In general, Sakha is the coldest Siberian region, and the basin of the Yana River has the lowest temperatures of all, with permafrost reaching 1,493 metres (4,898 ft). Nevertheless, as far as Imperial Russian plans of settlement were concerned, cold was never viewed as an issue. In the winter, southern Siberia sits near the center of the semi-permanent Siberian High, so winds are usually light in the winter.

Precipitation in Siberia is generally low, exceeding 500 millimeters (20 in) only in Kamchatka where moist winds flow from the Sea of Okhotsk onto high mountains – producing the region's only major glaciers, though volcanic eruptions and low summer temperatures allow limited forests to grow. Precipitation is high also in most of Primorye in the extreme south where monsoonal influences can produce quite heavy summer rainfall.

Climate data for Novosibirsk, Siberia's largest city
Month Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Year
Average high °C (°F) −12.2
(10)
−10.3
(13.5)
−2.6
(27.3)
8.1
(46.6)
17.5
(63.5)
24.0
(75.2)
25.7
(78.3)
22.2
(72)
16.6
(61.9)
6.8
(44.2)
−2.9
(26.8)
−8.9
(16)
7.0
(44.6)
Daily mean °C (°F) −16.2
(2.8)
−14.7
(5.5)
−7.2
(19)
3.2
(37.8)
11.6
(52.9)
18.2
(64.8)
20.2
(68.4)
17.0
(62.6)
11.5
(52.7)
3.4
(38.1)
−6.0
(21.2)
−12.7
(9.1)
2.4
(36.3)
Average low °C (°F) −20.1
(−4.2)
−19.1
(−2.4)
−11.8
(10.8)
−1.7
(28.9)
5.6
(42.1)
12.3
(54.1)
14.7
(58.5)
11.7
(53.1)
6.4
(43.5)
0.0
(32)
−9.1
(15.6)
−16.4
(2.5)
−2.3
(27.9)
Precipitation mm (inches) 19
(0.75)
14
(0.55)
15
(0.59)
24
(0.94)
36
(1.42)
58
(2.28)
72
(2.83)
66
(2.6)
44
(1.73)
38
(1.5)
32
(1.26)
24
(0.94)
442
(17.4)
Source: [31]
Researchers, including Sergei Kirpotin at Tomsk State University and Judith Marquand at Oxford University, warn that Western Siberia has begun to thaw as a result of global warming. The frozen peat bogs in this region may hold billions of tons of methane gas, which may be released into the atmosphere. Methane is a greenhouse gas 22 times more powerful than carbon dioxide.[32] In 2008, a research expedition for the American Geophysical Union detected levels of methane up to 100 times above normal in the Siberian Arctic, likely being released by methane clathrates being released by holes in a frozen 'lid' of seabed permafrost, around the outfall of the Lena River and the area between the Laptev Sea and East Siberian Sea.[33][34]

Politics

Borders and administrative division


Map of the most populated area of Siberia with clickable city names (SVG).

The term "Siberia" has a long history. Its meaning has gradually changed during ages. Historically, Siberia was defined as the whole part of Russia to the east of Ural Mountains, including the Russian Far East. According to this definition, Siberia extended eastward from the Ural Mountains to the Pacific coast, and southward from the Arctic Ocean to the border of Russian Central Asia and the national borders of both Mongolia and China.[35]

Soviet-era sources (Great Soviet Encyclopedia and others)[36] and modern Russian ones[37] usually define Siberia as a region extending eastward from the Ural Mountains to the watershed between Pacific and Arctic drainage basins, and southward from the Arctic Ocean to the hills of north-central Kazakhstan and the national borders of both Mongolia and China. By this definition, Siberia includes the federal subjects of the Siberian Federal District, and some of the Urals Federal District, as well as Sakha (Yakutia) Republic, which is a part of the Far Eastern Federal District. Geographically, this definition includes subdivisions of several other subjects of Urals and Far Eastern federal districts, but they are not included administratively. This definition excludes Sverdlovsk Oblast and Chelyabinsk Oblast, both of which are included in some wider definitions of Siberia.

Other sources may use either a somewhat wider definition that states the Pacific coast, not the watershed, is the eastern boundary (thus including the whole Russian Far East)[38] or a somewhat narrower one that limits Siberia to the Siberian Federal District (thus excluding all subjects of other districts).[39] In Russian, the word for Siberia is used as a substitute for the name of the federal district by those who live in the district itself and less commonly used to denote the federal district by people residing outside of it.

Federal subjects of Siberia (GSE)
subject administrative center
Urals Federal District
Khanty–Mansi Autonomous Okrug Khanty-Mansiysk
Kurgan Oblast Kurgan
Tyumen Oblast Tyumen
Yamalo-Nenets Autonomous Okrug Salekhard
Siberian Federal District
Altai Krai Barnaul
Altai Republic Gorno-Altaysk
Buryat Republic Ulan-Ude
Irkutsk Oblast Irkutsk
Republic of Khakassia Abakan
Kemerovo Oblast Kemerovo
Krasnoyarsk Krai Krasnoyarsk
Novosibirsk Oblast Novosibirsk
Omsk Oblast Omsk
Tomsk Oblast Tomsk
Tuva Republic Kyzyl
Zabaykalsky Krai Chita
Far Eastern Federal District
Sakha (Yakutia) Republic Yakutsk
Federal subjects of Siberia (in wide sense)
subject administrative center
Far Eastern Federal District
Amur Oblast Blagoveshchensk
Chukotka Autonomous Okrug Anadyr
Jewish Autonomous Oblast Birobidzhan
Kamchatka Krai Petropavlovsk-Kamchatsky
Khabarovsk Krai Khabarovsk
Magadan Oblast Magadan
Primorsky Krai Vladivostok
Sakhalin Oblast Yuzhno-Sakhalinsk
Urals Federal District
Chelyabinsk Oblast Chelyabinsk
Sverdlovsk Oblast Yekaterinburg

Major cities


City Day celebrations in Omsk

Krasny prospect, Novosibirsk

The most populous city of Siberia, as well as the third most populous city of Russia, is the city of Novosibirsk.
Other major cities include:
Wider definitions of Siberia also include:

Economy


Russia is a key oil and gas supplier to much of Europe.

Siberia is extraordinarily rich in minerals, containing ores of almost all economically valuable metals—largely because of the absence of Quaternary glaciation outside highland areas. It has some of the world's largest deposits of nickel, gold, lead, coal, molybdenum, gypsum, diamonds, diopside, silver and zinc, as well as extensive unexploited resources of oil and natural gas.[40] Around 70% of Russia's developed oil fields are in the Khanty-Mansiysk region.[41] Russia contains about 40% of the world's known resources of nickel at the Norilsk deposit in Siberia. Norilsk Nickel is the world's biggest nickel and palladium producer.[42]

Siberian agriculture is severely restricted by the short growing season of most of the region. However, in the southwest where soils are exceedingly fertile black earths and the climate is a little more moderate, there is extensive cropping of wheat, barley, rye and potatoes, along with the grazing of large numbers of sheep and cattle. Elsewhere food production, owing to the poor fertility of the podzolic soils and the extremely short growing seasons, is restricted to the herding of reindeer in the tundra—which has been practiced by natives for over 10,000 years. Siberia has the world's largest forests. Timber remains an important source of revenue, even though many forests in the east have been logged much more rapidly than they are able to recover. The Sea of Okhotsk is one of the two or three richest fisheries in the world owing to its cold currents and very large tidal ranges, and thus Siberia produces over 10% of the world's annual fish catch, although fishing has declined somewhat since the collapse of the USSR.[43]

Sport

Bandy, which is the national sport of Russia[44] is even more popular in Siberia than in European Russia.
Professional football teams include FC Tom Tomsk, FC Sibir Novosibirsk and FK Yenisey Krasnoyarsk.
The Yenisey Krasnoyarsk basketball team has played in the VTB United League since 2011.

Demographics

Tomsk, one of the oldest Siberian cities, was founded in 1604

According to the Russian Census of 2010, the Siberian and Far Eastern Federal Districts, located entirely east of the Ural mountains, together have a population of about 25.6 million. Tyumen and Kurgan Oblasts, which are geographically in Siberia but administratively part of the Urals Federal District, together have a population of about 4.3 million. Thus, the whole region of Asian Russia (or Siberia in the broadest usage of the term) is home to approximately 30 million people.[45] It has a population density of about three people per square kilometer.

Most Siberians are Russians and russified Ukrainians.[46] There are approximately 400,000 russified ethnic Germans living in Siberia.[47] Mongol and Turkic groups such as Buryats, Tuvinians, Yakuts, and Siberian Tatars[48] lived in Siberia originally, and descendants of these peoples still live there.[49] The Buryats numbering approximately 500,000, are the largest indigenous group in Siberia, mainly concentrated in their homeland, the Buryat Republic.[50] According to the 2002 census there were 443,852 Yakuts.[51] Other ethnic groups include Kets, Evenks, Chukchis, Koryaks, Yupiks, and Yukaghirs. The Slavic Russians outnumber all of the native peoples in Siberia and its cities except in the Republic of Tuva, with the Slavic Russians making up the majority in the Buriat Republic, Sakha Republic, and Altai Republics, outnumbering the Buriat, Sakha, and Altai natives. The Buriat make up only 25% of their own Republic, and the Sakha and Altai each are only one-third, and the Chukchi, Evenk, Khanti, Mansi, and Nenets are outnumbered by non-natives by 90% of the population.[52]

About seventy percent of Siberia's people live in cities, mainly in apartments. Many people also live in rural areas, in simple, spacious, log houses. Novosibirsk is the largest city in Siberia, with a population of about 1.5 million. Tobolsk, Tomsk, Tyumen, Krasnoyarsk, Irkutsk and Omsk are the older, historical centers.

Religion


There are a variety of beliefs throughout Siberia, including Orthodox Christianity, other denominations of Christianity, Tibetan Buddhism and Islam.[53] An estimated 70,000 Jews live in Siberia,[54] and there is also the Jewish Autonomous Region.[55] The predominant group is the Russian Orthodox Church.

Siberia is regarded as the locus classicus of shamanism, and polytheism is popular.[56] These native religions date back hundreds of years. The vast terrority of Siberia has many different local traditions of gods. These include: Ak Ana, Anapel, Bugady Musun, Kara Khan, Khaltesh-Anki, Kini'je, Ku'urkil, Nga, Nu'tenut, Numi-Torem, Numi-Turum, Pon, Pugu, Todote, Toko'yoto, Tomam, Xaya Iccita, Zonget. Places with sacred areas include Olkhon, an island in Lake Baikal.

Transport

Many cities in Siberia, such as Petropavlovsk-Kamchatsky, cannot be reached by road, as there are virtually none connecting from other major cities in Russia or Asia. The best way to tour Siberia is through the Trans-Siberian Railway. The Trans-Siberian Railway operates from Moscow in the west to Vladivostok in the east. Cities not near the railway are best reached by air or by the separate Baikal-Amur-Railway (BAM).

Climate expert John Christy on funding: 'No one is paying me to have my view'

By Paul Gattis | pgattis@al.com
Email the author | Follow on Twitter
Original link:  http://www.al.com/news/huntsville/index.ssf/2015/03/climate_expert_john_christy_on.html?ath=3684250753c62b8752e8389d42ec3545
 










Christy chart  
A chart provided to AL.com by UAH climate expert John Christy that shows the disparity between climate models and research conducted by UAH. The green line is satellite data compiled by UAH while the blue is from weather balloon data compiled by an independent entity, Christy said. 

John Christy, a climate expert at the University of Alabama in Huntsville, said Tuesday that he has not accepted any funding from the fossil fuel industry.

Christy's response in an interview with AL.com resulted from an inquiry from an Arizona congressman who has asked about Christy's funding sources as part of a probe of climate change skeptics.

"My response is that I don't see anything in this letter that challenges the science we produce," he said. "So therefore, it should not matter where support came from to produce that science. (The Obama) administration believes that if you don't agree with them about climate change, you must be being paid to have that opinion.
"In my case, they won't find anything -- 100 percent of my support is state and federal grants. No one is paying me to have my view. I have my view because I'm a climate scientist and that's what the data shows."

U.S. Rep. Raul Grijalva, D-Arizona, announced last month he was sending letters to seven climate change skeptics in an effort to determine if their positions were defined because they accepted funding from fossil fuel industries. A group of Republican senators, including Alabama's Jeff Sessions, have questioned the worthiness of the inquiry.

sessions chartSen. Jeff Sessions uses the Christy chart in a presentation on the Senate floor on Jan. 27, 2015. 

Christy, the director of the Earth System Science Center at UAH, said he was meeting with the UAH administration on Wednesday to formally respond to Grijalva's letter. Christy said UAH officials have verified his outside sources of income.

"It's not going to work as intimidation, which is what it's designed to do," Christy said of the letter. "But it does have a backfire aspect to it. It emboldens you when you've gotten under somebody's skin because you know this is what the real world is doing."

Christy said the Obama administration is working to silence those skeptical of dangerous climate change by December in advance of a new global climate agreement. The Grijalva letter is part of that effort, Christy said.

In an interview with Vice News released Monday, Obama put the onus on Republicans when it comes to climate change policy.

"I guarantee that the Republican Party will have to change its approach to climate change because voters will insist upon it," Obama said, according to a report by The Hill.

"I think they think this is their signature issue," Christy said. "And to get that done by December, they've got squelch any opposition they can right now. And to say Republicans have to believe a certain thing, that's a political move, not a scientific move."

Christy referred to a UAH chart that compared 102 climate models produced by the Intergovernmental Panel on Climate Change with satellite data collected by UAH that reflects that the models are far out of step with the actual data when it comes to climate change. The chart dates from 1975 to 2014.

The chart suggests warming is happening at about eight-tenths of a degree in 2014, according to the IPCC data, while the UAH data indicates warming has been about two-tenths of a degree over the same time period.

The IPCC models, according to the UAH chart, estimated global temperatures to be higher than what the actual data revealed in past years.

"These models can't even predict what happened in the past," Christy said. "Doesn't that ring alarm bells in your mind about trusting this as a policy tool?"

Atomic force microscopy


From Wikipedia, the free encyclopedia


An atomic force microscope on the left with controlling computer on the right.

Block diagram of atomic force microscope using beam deflection detection. As the cantilever is displaced via its interaction with the surface, so too will the reflection of the laser beam be displaced on the surface of the photodiode.

Atomic force microscopy (AFM) or scanning force microscopy (SFM) is a very high-resolution type of scanning probe microscopy, with demonstrated resolution on the order of fractions of a nanometer, more than 1000 times better than the optical diffraction limit. The precursor to the AFM, the scanning tunneling microscope, was developed by Gerd Binnig and Heinrich Rohrer in the early 1980s at IBM Research - Zurich, a development that earned them the Nobel Prize for Physics in 1986. Binnig invented[1] the atomic force microscope and the first experimental implementation was made by Binnig, Quate and Gerber in 1986.[2] The first commercially available atomic force microscope was introduced in 1989. The AFM is one of the foremost tools for imaging, measuring, and manipulating matter at the nanoscale. The information is gathered by "feeling" the surface with a mechanical probe. Piezoelectric elements that facilitate tiny but accurate and precise movements on (electronic) command enable the very precise scanning. In some variations, electric potentials can also be scanned using conducting cantilevers. In more advanced versions, currents can be passed through the tip to probe the electrical conductivity or transport of the underlying surface, but this is much more challenging with few research groups reporting consistent data (as of 2004).[3]

Basic principles

Electron micrograph of a used AFM cantilever image width ~100 micrometers...
and ~30 micrometers

The AFM consists of a cantilever with a sharp tip (probe) at its end that is used to scan the specimen surface. The cantilever is typically silicon or silicon nitride with a tip radius of curvature on the order of nanometers. When the tip is brought into proximity of a sample surface, forces between the tip and the sample lead to a deflection of the cantilever according to Hooke's law.[4] Depending on the situation, forces that are measured in AFM include mechanical contact force, van der Waals forces, capillary forces, chemical bonding, electrostatic forces, magnetic forces (see magnetic force microscope, MFM), Casimir forces, solvation forces, etc. Along with force, additional quantities may simultaneously be measured through the use of specialized types of probes (see scanning thermal microscopy, scanning joule expansion microscopy, photothermal microspectroscopy, etc.). Typically, the deflection is measured using a laser spot reflected from the top surface of the cantilever into an array of photodiodes. Other methods that are used include optical interferometry, capacitive sensing or piezoresistive AFM cantilevers. These cantilevers are fabricated with piezoresistive elements that act as a strain gauge. Using a Wheatstone bridge, strain in the AFM cantilever due to deflection can be measured, but this method is not as sensitive as laser deflection or interferometry.[citation needed]

Atomic force microscope topographical scan of a glass surface. The micro and nano-scale features of the glass can be observed, portraying the roughness of the material. The image space is (x,y,z) = (20 µm × 20 µm × 420 nm).

If the tip was scanned at a constant height, a risk would exist that the tip collides with the surface, causing damage. Hence, in most cases a feedback mechanism is employed to adjust the tip-to-sample distance to maintain a constant force between the tip and the sample. Traditionally the tip or sample is mounted on a 'tripod' of three piezo crystals, with each responsible for scanning in the x,y and z directions.[5] In 1986, the same year as the AFM was invented, a new piezoelectric scanner, the tube scanner, was developed for use in STM.[6] Later tube scanners were incorporated into AFMs. The tube scanner can move the sample in the x, y, and z directions using a single tube piezo with a single interior contact and four external contacts. An advantage of the tube scanner is better vibrational isolation, resulting from the higher resonant frequency of the single-crystal construction in combination with a low resonant frequency isolation stage. A disadvantage is that the x-y motion can cause unwanted z motion resulting in distortion.

The AFM can be operated in a number of modes, depending on the application. In general, possible imaging modes are divided into static (also called contact) modes and a variety of dynamic (non-contact or "tapping") modes where the cantilever is vibrated.[5]

Probe

An AFM probe has a sharp tip on the free-swinging end of a cantilever that is protruding from a holder plate.[7] The dimensions of the cantilever are in the scale of micrometers. The radius of the tip is usually on the scale of a few nanometers to a few tens of nanometers. (Specialized probes exist with much larger end radii, for example probes for indentation of soft materials.) The holder plate, also called holder chip, - often 1.6 mm by 3.4 mm in size - allows the operator to hold the AFM probe with tweezers and fit it into the corresponding holder clips on the scanning head of the atomic force microscope.

This device is most commonly called an "AFM probe", but other names include "AFM tip" and "cantilever" (employing the name of a single part as the name of the whole device). An AFM probe is a particular type of SPM (scanning probe microscopy) probe.

AFM probes are manufactured with MEMS technology. Most AFM probes used are made from silicon (Si), but borosilicate glass and silicon nitride are also in use. AFM probes are considered consummables as they are often replaced when the tip apex becomes dull or contaminated or when the cantilever is broken.

Just the tip is brought very close to the surface of the object under investigation, the cantilever is deflected by the interaction between the tip and the surface, which is what the AFM is designed to measure. A spatial map of the interaction can be made by measuring the deflection at many points of a 2D surface.

Several types of interaction can be detected. Depending on the interaction under investigation, the surface of the tip of the AFM probe needs to be modified with a coating. Among the coatings used are gold - for covalent bonding of biological molecules and the detection of their interaction with a surface,[8] diamond for increased wear resistance[9] and magnetic coatings for detecting the magnetic properties of the investigated surface.[10]

The surface of the cantilevers can also be modified. These coatings are mostly applied in order to increase the reflectance of the cantilever and to improve the deflection signal.

Imaging modes

AFM operation is usually described as one of three modes, according to the nature of the tip motion:
  • contact mode, also called static mode (as opposed to the other two modes, which are called dynamic modes)
  • tapping mode, also called intermittent contact, AC mode, or vibrating mode, or, after the detection mechanism, amplitude modulation AFM
  • non-contact mode, or, again after the detection mechanism, frequency modulation AFM

Contact mode

In contact mode, the tip is "dragged" across the surface of the sample and the contours of the surface are measured either using the deflection of the cantilever directly or, more commonly, using the feedback signal required to keep the cantilever at a constant position. Because the measurement of a static signal is prone to noise and drift, low stiffness cantilevers are used to boost the deflection signal. Close to the surface of the sample, attractive forces can be quite strong, causing the tip to "snap-in" to the surface. Thus, contact mode AFM is almost always done at a depth where the overall force is repulsive, that is, in firm "contact" with the solid surface below any adsorbed layers.

Tapping mode


Single polymer chains (0.4 nm thick) recorded in a tapping mode under aqueous media with different pH.[11]

In ambient conditions, most samples develop a liquid meniscus layer. Because of this, keeping the probe tip close enough to the sample for short-range forces to become detectable while preventing the tip from sticking to the surface presents a major problem for non-contact dynamic mode in ambient conditions. Dynamic contact mode (also called intermittent contact, AC mode or tapping mode) was developed to bypass this problem.[12]

In tapping mode, the cantilever is driven to oscillate up and down at near its resonance frequency by a small piezoelectric element mounted in the AFM tip holder similar to non-contact mode. However, the amplitude of this oscillation is greater than 10 nm, typically 100 to 200 nm. The interaction of forces acting on the cantilever when the tip comes close to the surface, Van der Waals forces, dipole-dipole interactions, electrostatic forces, etc. cause the amplitude of this oscillation to decrease as the tip gets closer to the sample. An electronic servo uses the piezoelectric actuator to control the height of the cantilever above the sample. The servo adjusts the height to maintain a set cantilever oscillation amplitude as the cantilever is scanned over the sample. A tapping AFM image is therefore produced by imaging the force of the intermittent contacts of the tip with the sample surface.[13]

This method of "tapping" lessens the damage done to the surface and the tip compared to the amount done in contact mode. Tapping mode is gentle enough even for the visualization of supported lipid bilayers or adsorbed single polymer molecules (for instance, 0.4 nm thick chains of synthetic polyelectrolytes) under liquid medium. With proper scanning parameters, the conformation of single molecules can remain unchanged for hours.[11]

Non-contact mode


AFM – non-contact mode

In non-contact atomic force microscopy mode, the tip of the cantilever does not contact the sample surface. The cantilever is instead oscillated at either its resonant frequency (frequency modulation) or just above (amplitude modulation) where the amplitude of oscillation is typically a few nanometers (<10 nm) down to a few picometers.[14] The van der Waals forces, which are strongest from 1 nm to 10 nm above the surface, or any other long-range force that extends above the surface acts to decrease the resonance frequency of the cantilever. This decrease in resonant frequency combined with the feedback loop system maintains a constant oscillation amplitude or frequency by adjusting the average tip-to-sample distance. Measuring the tip-to-sample distance at each (x,y) data point allows the scanning software to construct a topographic image of the sample surface.

Non-contact mode AFM does not suffer from tip or sample degradation effects that are sometimes observed after taking numerous scans with contact AFM. This makes non-contact AFM preferable to contact AFM for measuring soft samples, e.g. biological samples and organic thin film. In the case of rigid samples, contact and non-contact images may look the same. However, if a few monolayers of adsorbed fluid are lying on the surface of a rigid sample, the images may look quite different. An AFM operating in contact mode will penetrate the liquid layer to image the underlying surface, whereas in non-contact mode an AFM will oscillate above the adsorbed fluid layer to image both the liquid and surface.

Schemes for dynamic mode operation include frequency modulation where a phase-locked loop is used to track the cantilever's resonance frequency and the more common amplitude modulation with a servo loop in place to keep the cantilever excitation to a defined amplitude. In frequency modulation, changes in the oscillation frequency provide information about tip-sample interactions. Frequency can be measured with very high sensitivity and thus the frequency modulation mode allows for the use of very stiff cantilevers. Stiff cantilevers provide stability very close to the surface and, as a result, this technique was the first AFM technique to provide true atomic resolution in ultra-high vacuum conditions.[15]

In amplitude modulation, changes in the oscillation amplitude or phase provide the feedback signal for imaging. In amplitude modulation, changes in the phase of oscillation can be used to discriminate between different types of materials on the surface. Amplitude modulation can be operated either in the non-contact or in the intermittent contact regime. In dynamic contact mode, the cantilever is oscillated such that the separation distance between the cantilever tip and the sample surface is modulated.

Amplitude modulation has also been used in the non-contact regime to image with atomic resolution by using very stiff cantilevers and small amplitudes in an ultra-high vacuum environment.

AFM cantilever deflection measurement

Beam deflection measurement


AFM beam deflection detection

The most common method for cantilever deflection measurements is the beam deflection method. In this method, laser light from a solid-state diode is reflected off the back of the cantilever and collected by a position-sensitive detector (PSD) consisting of two closely spaced photodiodes whose output signal is collected by a differential amplifier. Angular displacement of the cantilever results in one photodiode collecting more light than the other photodiode, producing an output signal (the difference between the photodiode signals normalized by their sum), which is proportional to the deflection of the cantilever. It detects cantilever deflections <10 nm (thermal noise limited). A long beam path (several centimeters) amplifies changes in beam angle.

Other deflection measurement methods

Many other methods for beam deflection measurements exist.
  • Piezoelectric detection — Cantilevers made from quartz[16] (such as the qPlus configuration), or other piezoelectric materials can directly detect deflection as an electrical signal. Cantilever oscillations down to 10pm have been detected with this method.
  • Laser Doppler vibrometry — A laser Doppler vibrometer can be used to produce very accurate deflection measurements for an oscillating cantilever[17] (thus is only used in non-contact mode). This method is expensive and is only used by relatively few groups.
  • STM — The first atomic microscope used an STM complete with its own feedback mechanism to measure deflection.[5] This method is very difficult to implement, and is slow to react to deflection changes compared to modern methods.
  • Optical InterferometryOptical interferometry can be used to measure cantilever deflection.[18] Due to the nanometre scale deflections measured in AFM, the interferometer is running in the sub-fringe regime, thus, any drift in laser power or wavelength has strong effects on the measurement. For these reasons optical interferometer measurements must be done with great care (for example using index matching fluids between optical fibre junctions), with very stable lasers. For these reasons optical interferometry is rarely used.
  • Capacitive detection — Metal coated cantilevers can form a capacitor with another contact located behind the cantilever.[19] Deflection changes the distance between the contacts and can be measured as a change in capacitance.
  • Piezoresistive detection — Similar to piezoelectric detection, but uses piezoresistive cantilevers to measure the detection.[20] This is not commonly used as the piezoresistive detection dissipates energy from the system affecting Q of the resonance.

Force spectroscopy

Another major application of AFM (besides imaging) is force spectroscopy, the direct measurement of tip-sample interaction forces as a function of the gap between the tip and sample (the result of this measurement is called a force-distance curve). For this method, the AFM tip is extended towards and retracted from the surface as the deflection of the cantilever is monitored as a function of piezoelectric displacement. These measurements have been used to measure nanoscale contacts, atomic bonding, Van der Waals forces, and Casimir forces, dissolution forces in liquids and single molecule stretching and rupture forces.[21] Furthermore, AFM was used to measure, in an aqueous environment, the dispersion force due to polymer adsorbed on the substrate.[22] Forces of the order of a few piconewtons can now be routinely measured with a vertical distance resolution of better than 0.1 nanometers. Force spectroscopy can be performed with either static or dynamic modes. In dynamic modes, information about the cantilever vibration is monitored in addition to the static deflection.[23]

Problems with the technique include no direct measurement of the tip-sample separation and the common need for low-stiffness cantilevers, which tend to 'snap' to the surface. These problems are not insurmountable. An AFM that directly measures the tip-sample separation has been developed.[24] The snap-in can be reduced by measuring in liquids or by using stiffer cantilevers, but in the latter case a more sensitive deflection sensor is needed. By applying a small dither to the tip, the stiffness (force gradient) of the bond can be measured as well.[25]

Biological applications

Force spectroscopy is used in biophysics to measure the mechanical properties of living material (such as tissue or cells).[26]

Identification of individual surface atoms

The AFM can be used to image and manipulate atoms and structures on a variety of surfaces. The atom at the apex of the tip "senses" individual atoms on the underlying surface when it forms incipient chemical bonds with each atom. Because these chemical interactions subtly alter the tip's vibration frequency, they can be detected and mapped. This principle was used to distinguish between atoms of silicon, tin and lead on an alloy surface, by comparing these 'atomic fingerprints' to values obtained from large-scale density functional theory (DFT) simulations.[27]

The trick is to first measure these forces precisely for each type of atom expected in the sample, and then to compare with forces given by DFT simulations. The team found that the tip interacted most strongly with silicon atoms, and interacted 23% and 41% less strongly with tin and lead atoms, respectively. Thus, each different type of atom can be identified in the matrix as the tip is moved across the surface.

Advantages and disadvantages


The first atomic force microscope

Just like any other tool, an AFM's usefulness has limitations. When determining whether or not analyzing a sample with an AFM is appropriate, there are various advantages and disadvantages that must be considered.

Advantages

AFM has several advantages over the scanning electron microscope (SEM). Unlike the electron microscope, which provides a two-dimensional projection or a two-dimensional image of a sample, the AFM provides a three-dimensional surface profile. In addition, samples viewed by AFM do not require any special treatments (such as metal/carbon coatings) that would irreversibly change or damage the sample, and does not typically suffer from charging artifacts in the final image. While an electron microscope needs an expensive vacuum environment for proper operation, most AFM modes can work perfectly well in ambient air or even a liquid environment. This makes it possible to study biological macromolecules and even living organisms. In principle, AFM can provide higher resolution than SEM. It has been shown to give true atomic resolution in ultra-high vacuum (UHV) and, more recently, in liquid environments. High resolution AFM is comparable in resolution to scanning tunneling microscopy and transmission electron microscopy. AFM can also be combined with a variety of optical microscopy techniques such as fluorescent microscopy, further expanding its applicability. Combined AFM-optical instruments have been applied primarily in the biological sciences but have also found a niche in some materials applications, especially those involving photovoltaics research.[13]

Disadvantages

A disadvantage of AFM compared with the scanning electron microscope (SEM) is the single scan image size. In one pass, the SEM can image an area on the order of square millimeters with a depth of field on the order of millimeters, whereas the AFM can only image a maximum height on the order of 10-20 micrometers and a maximum scanning area of about 150×150 micrometers. One method of improving the scanned area size for AFM is by using parallel probes in a fashion similar to that of millipede data storage.

The scanning speed of an AFM is also a limitation. Traditionally, an AFM cannot scan images as fast as a SEM, requiring several minutes for a typical scan, while a SEM is capable of scanning at near real-time, although at relatively low quality. The relatively slow rate of scanning during AFM imaging often leads to thermal drift in the image[28][29][30] making the AFM less suited for measuring accurate distances between topographical features on the image. However, several fast-acting designs [31][32] were suggested to increase microscope scanning productivity including what is being termed videoAFM (reasonable quality images are being obtained with videoAFM at video rate: faster than the average SEM). To eliminate image distortions induced by thermal drift, several methods have been introduced.[28][29][30]

AFM images can also be affected by nonlinearity, hysteresis,[33] and creep of the piezoelectric material and cross-talk between the x, y, z axes that may require software enhancement and filtering. Such filtering could "flatten" out real topographical features. However, newer AFMs utilize real-time correction software (for example, feature-oriented scanning[28][34]) or closed-loop scanners, which practically eliminate these problems. Some AFMs also use separated orthogonal scanners (as opposed to a single tube), which also serve to eliminate part of the cross-talk problems.


Showing an AFM artifact arising from a tip with a high radius of curvature with respect to the feature that is to be visualized.

As with any other imaging technique, there is the possibility of image artifacts, which could be induced by an unsuitable tip, a poor operating environment, or even by the sample itself, as depicted on the right. These image artifacts are unavoidable; however, their occurrence and effect on results can be reduced through various methods. Artifacts resulting from a too-coarse tip can be caused for example by inappropriate handling or de facto collisions with the sample by either scanning too fast or having an unreasonably rough surface, causing actual wearing of the tip.

AFM artifact, steep sample topography

Due to the nature of AFM probes, they cannot normally measure steep walls or overhangs. Specially made cantilevers and AFMs can be used to modulate the probe sideways as well as up and down (as with dynamic contact and non-contact modes) to measure sidewalls, at the cost of more expensive cantilevers, lower lateral resolution and additional artifacts.

Piezoelectric scanners

AFM scanners are made from piezoelectric material, which expands and contracts proportionally to an applied voltage. Whether they elongate or contract depends upon the polarity of the voltage applied. The scanner is constructed by combining independently operated piezo electrodes for X, Y, and Z into a single tube, forming a scanner that can manipulate samples and probes with extreme precision in 3 dimensions. Independent stacks of piezos can be used instead of a tube, resulting in decoupled X, Y, and Z movement.

Scanners are characterized by their sensitivity, which is the ratio of piezo movement to piezo voltage, i.e., by how much the piezo material extends or contracts per applied volt. Because of differences in material or size, the sensitivity varies from scanner to scanner. Sensitivity varies non-linearly with respect to scan size. Piezo scanners exhibit more sensitivity at the end than at the beginning of a scan. This causes the forward and reverse scans to behave differently and display hysteresis between the two scan directions.[33] This can be corrected by applying a non-linear voltage to the piezo electrodes to cause linear scanner movement and calibrating the scanner accordingly.[33] One disadvantage of this approach is that it requires re-calibration because the precise non-linear voltage needed to correct non-linear movement will change as the piezo ages (see below). This problem can be circumvented by adding a linear sensor to the sample stage or piezo stage to detect the true movement of the piezo. Deviations from ideal movement can be detected by the sensor and corrections applied to the piezo drive signal to correct for non-linear piezo movement. This design is known as a 'closed loop' AFM. Non-sensored piezo AFMs are referred to as 'open loop' AFMs.

The sensitivity of piezoelectric materials decreases exponentially with time. This causes most of the change in sensitivity to occur in the initial stages of the scanner’s life. Piezoelectric scanners are run for approximately 48 hours before they are shipped from the factory so that they are past the point where they may have large changes in sensitivity. As the scanner ages, the sensitivity will change less with time and the scanner would seldom require recalibration,[34][35] though various manufacturer manuals recommend monthly to semi-monthly calibration of open loop AFMs.

Detection of mini black holes at the LHC could indicate parallel universes in extra dimensions

Original link:  http://phys.org/news/2015-03-mini-black-holes-lhc-parallel.html
by Lisa Zyga feature

Large Hadron Collider 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Credit: CERN
(Phys.org)—The possibility that other universes exist beyond our own universe is tantalizing, but seems nearly impossible to test. Now a group of physicists has suggested that the Large Hadron Collider (LHC), the largest particle collider in the world, may be able to uncover the existence of parallel universes, should they exist.

In a new paper published in Physics Letters B, Ahmed Farag Ali, Mir Faizal, and Mohammed M. Khalil explain that the key to finding may come from detecting miniature black holes at a certain energy level. The detection of the mini black holes would indicate the existence of extra dimensions, which would support string theory and related models that predict the existence of extra dimensions as well as parallel universes.

"Normally, when people think of the multiverse, they think of the many-worlds interpretation of quantum mechanics, where every possibility is actualized," Faizal told Phys.org. "This cannot be tested and so it is philosophy and not science. This is not what we mean by parallel universes. What we mean is real universes in extra dimensions. As can flow out of our universe into the extra dimensions, such a model can be tested by the detection of mini black holes at the LHC. We have calculated the energy at which we expect to detect these mini black holes in gravity's rainbow [a new theory]. If we do detect mini black holes at this energy, then we will know that both gravity's rainbow and extra dimensions are correct."

The search continues

In some ways, this idea is not new. The LHC has already been trying to detect mini black holes, but has come up empty-handed. This is what would be expected if there are only four dimensions, since the energy required to produce black holes in four dimensions would be much larger (1019 GeV) than the energy that can be achieved at the LHC (14 TeV).

However, if extra dimensions do exist, it is thought that they would lower the energy required to produce black holes to levels that that the LHC can achieve. As Faizal explained, this happens because the gravity in our universe may somehow flow into the extra dimensions. As the LHC has so far not detected mini black holes, it seems that extra dimensions do not exist, at least not at the energy scale that was tested. By extension, the results do not support string theory or parallel universes, either.

In their paper, Ali, Faizal, and Khalil offer a different interpretation for why mini black holes have not been detected at the LHC. They suggest that the current model of gravity that was used to predict the required energy level for black hole production is not quite accurate because it does not account for quantum effects.

According to Einstein's general theory of relativity, gravity can be thought of as the curvature of space and time. However, here the scientists point out that this geometry of space and time responsible for gravity gets deformed at the Planck scale. They have used the new theory of gravity's rainbow to account for this modification of the geometry of space and time near the Planck scale, where the mini black holes are predicted to exist.

Using gravity's rainbow, the scientists found that a little bit more energy is required to produce mini black holes at the LHC than previously thought. So far, the LHC has searched for mini black holes at energy levels below 5.3 TeV. According to gravity's rainbow, this energy is too low. Instead, the model predicts that black holes may form at of at least 9.5 TeV in six dimensions and 11.9 TeV in 10 dimensions. Since the LHC is designed to reach 14 TeV in future runs, these predicted energy requirements for black hole production should be accessible.

Many interpretations

If mini black holes are detected at the LHC, then it would arguably support several ideas: parallel universes, extra dimensions, , and gravity's rainbow—with these last two having implications for a theory of quantum gravity. Most obviously, a positive result would support the existence of mini black holes themselves.

"If mini black holes are detected at the LHC at the predicted energies, not only will it prove the existence of extra dimensions and by extension parallel universes, but it will also solve the famous information paradox in black holes," Ali said. Solving the paradox is possible because, in the gravity's rainbow model, mini black holes have a minimum radius below which they cannot shrink.

However, if black holes are not detected, the scientists will need to reexamine their understanding of these ideas.

"If are not detected at the predicted levels, this would mean one of three possibilities," Khalil explained. "One, do not exist. Two, they exist, but they are smaller than expected. Or three, the parameters of gravity's rainbow need to be modified."

In the world of theoretical physics, there is never just one interpretation, and the same goes for this issue. Remo Garattini, Professor of Physics at the University of Bergamo, has used gravity's rainbow in his work on regulating ultraviolet divergences, which have plagued models of . Although he is sympathetic to many of the ideas in gravity's rainbow, he points out that the current paper relies on only one proposal, which uses an equation that does not eliminate divergences.

"I think that the paper is interesting, but we have to be careful to extrapolate global results using only one proposal for the rainbow's functions," Garattini said.

Along these lines, Joao Magueijo, Professor of Physics at Imperial College London, cautions that the details of the theory that will either make it or break it. And at this early stage, it's difficult to tell what these details should be.

"The work is interesting, but like many other applications of rainbow gravity, it does depend crucially on the chosen free functions of the theory," Magueijo said. "Still, I think this work could be a valuable step in constraining those free functions."


More information: Ahmed Farag Ali, Mir Faizal, Mohammed M. Khalil. "Absence of black holes at LHC due to gravity's rainbow." Physics Letters B. DOI: 10.1016/j.physletb.2015.02.065

Second law of thermodynamics

From Wikipedia, the free encyclopedia https://en.wikipedia.org/wiki/Second_law_of_thermodynamics   The second law of t...