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Mars Base

Einstein Goes Online with Archive | Albert Einstein & History of Science | Physics | Sp... - 1 views

www.space.com/t-einstein-online-archive.html

scibyte39 einstein

shared by Mars Base on 21 Mar 12 - No Cached
  • anyone with Internet access can peek into one of the most celebrated minds in science
  • Albert Einstein's complete archive is gradually becoming available through the Einstein Archives Online
  • March 19), the online archive debuted with roughly 2,000 documents
  • ...9 more annotations...
  • archival database
  • more than 80,000 documen
  • peak at Einstein's high school certification
  • finishing high school at 16 in 1896
  • Einstein was an excellent student
  • he left because he couldn't handle the strict discipline and authority.
  • one of only three existing manuscripts containing the famous E=mc^2 equation written in Einstein's handwriting
  • archive contains a postcard to his mother
  • originally launched in 2003. Almost a decade later, a $500,000 grant from the Polonsky Foundation of London funded digitization of the 80,000 documents
Mars Base

Astronomers discover the largest structure in the universe - 0 views

phys.org/...ronomers-largest-universe.html

scibyte77 LQG

shared by Mars Base on 13 Jan 13 - No Cached
  • The large quasar group (LQG) is so large that it would take a vehicle travelling at the speed of light some 4 billion years to cross it.
  • Quasars are the nuclei of galaxies from the early days of the universe that undergo brief periods of extremely high brightness that make them visible across huge distances.
  • 'brief' in astrophysics terms but actually last 10-100 million years.
  • ...11 more annotations...
  • Since 1982 it has been known that quasars tend to group together in clumps or 'structures' of surprisingly large sizes, forming large quasar groups or LQGs.
  • the LQG which is so significant in size it also challenges the Cosmological Principle: the assumption that the universe, when viewed at a sufficiently large scale, looks the same no matter where you are observing it from.
  • The modern theory of cosmology is based on the work of Albert Einstein, and depends on the assumption of the Cosmological Principle
  • he Principle is assumed but has never been demonstrated observationally 'beyond reasonable doubt'.
  • the Milky Way, is separated from its nearest neighbour, the Andromeda Galaxy, by about 0.75 Megaparsecs (Mpc) or 2.5 million light-years.
  • Whole clusters of galaxies can be 2-3 Mpc
  • LQGs can be 200 Mpc or more across.
  • Based on the Cosmological Principle and the modern theory of cosmology, calculations suggest that astrophysicists should not be able to find a structure larger than 370 Mpc.
  • newly discovered LQG however has a typical dimension of 500 Mpc.
  • it is elongated, its longest dimension is 1200 Mpc (or 4 billion light years)
  • some 1600 times larger than the distance from the Milky Way to Andromed
Mars Base

Effects of Einstein's Elusive Gravity Waves Observed - 0 views

www.universetoday.com/...elusive-gravity-waves-observed

scibyte61

shared by Mars Base on 29 Aug 12 - No Cached
  • According to Einstein, space-time is a structure in itself
  • also predicted that exceptionally massive, rapidly rotating objects — such as a white dwarf binary pair — would create outwardly-expanding ripples in space-time that would ultimately “steal” kinetic energy from the objects themselves. These gravitational waves would be very subtle, yet in theory, observable.
  • Originally observed in 2011 eclipsing each other
  • ...4 more annotations...
  • once every six minutes, the stars now eclipse six seconds sooner
  • equates to a predicted orbital period reduction of about 0.25 milliseconds each year
  • Although this isn’t “direct” observation of gravitational waves, it is evidence inferred by their predicted effects… akin to watching a floating lantern in a dark pond at night moving up and down and deducing that there are waves present
  • Based on these measurements, by April 2013 the stars will be eclipsing each other 20 seconds sooner than first observed.
Mars Base

Astrophysicists spy ultra-distant galaxy amidst cosmic 'dark ages' - 0 views

phys.org/...tra-distant-galaxy-cosmic.html

scibyte64 galaxy

shared by Mars Base on 20 Sep 12 - No Cached
  • combined power of NASA's Spitzer and Hubble space telescopes as well as a cosmic magnification effect, a team
  • has spotted what could be the most distant galaxy ever detected.
  • Light from the young galaxy captured by the orbiting observatories shone forth when the 13.7-billion-year-old universe was just 500 million years old
  • ...19 more annotations...
  • This galaxy is the most distant object we have ever observed with high confidence
  • Future work involving this galaxy—as well as others like it that we hope to find—will allow us to study the universe's earliest objects and how the Dark Ages ended
  • traveled approximately 13.2 billion light-years
  • the universe was just 3.6 percent
  • Objects at these extreme distances are mostly beyond the detection sensitivity of today's largest telescopes
  • astronomers rely on "gravitational lensing
  • predicted by Albert Einstein a century ago
  • gravity of foreground objects warps and magnifies the light from background objects
  • brightening the remote object some 15 times and bringing it into view.
  • small and compact, containing only about 1 percent of the Milky Way's mass
  • leading cosmological theories, the first galaxies should indeed have started out tiny
  • then progressively merged
  • omers plan to study the rise of the first stars and galaxies and the epoch of reionization with the successor to both Spitzer and Hubble—NASA's James Webb Telescope, slated for launch in 2018
  • newly described distant galaxy will likely be a prime target.
  • first galaxies likely played the dominant role in the epoch of reionization
  • event that signaled the demise of the universe's Dark Ages
  • About 400,000 years after the Big Bang, neutral hydrogen gas formed from cooling particles
  • these earliest galaxies is thought to have caused the neutral hydrogen strewn throughout the universe to ionize, or lose an electron
  • during the epoch of reionization, the lights came on in the universe
Mars Base

Physicists create synthetic magnetic monopole predicted more than 80 years ago - 0 views

phys.org/...c-magnetic-monopole-years.html

scibyte118

shared by Mars Base on 30 Jan 14 - No Cached
  • Nearly 85 years
  • physicist
  • predicted the possibility
  • ...20 more annotations...
  • identified and photographed synthetic magnetic monopoles
  • The groundbreaking accomplishment paves the way for the detection of the particles in nature
  • "The creation of a synthetic magnetic monopole should provide us with unprecedented insight into aspects of the natural magnetic monopole—if indeed it exists,"
  • To be able to confirm the work of one of the most famous physicists is probably a once-in-a-lifetime opportunity
  • Ordinarily, magnetic poles come in pairs: they have both a north pole and a south pole
  • a magnetic monopole is a magnetic particle possessing only a single, isolated pole—a north pole without a south pole, or vice versa
  • . In 1931,
  • published a paper that explored the nature of these monopoles in the context of quantum mechanics
  • Despite extensive experimental searches since then, in everything from lunar samples—moon rock—to ancient fossilized minerals, no observation of a naturally-occurring magnetic monopole has yet been confirmed
  • team adopted an innovative approach to investigating
  • theory, creating and identifying synthetic magnetic monopoles
  • an artificial magnetic field generated by a Bose-Einstein condensate, an extremely cold atomic gas tens of billionths of a degree warmer than absolute zero.
  • The team relied upon theoretical work
  • that suggested a particular sequence of changing external magnetic fields could lead to the creation of the synthetic monopole
  • Their experiments subsequently took place in the atomic refrigerator built
  • in his basement laboratory in the Merrill Science Center
  • After resolving many technical challenges, the team was rewarded with photographs that confirmed the monopoles' presence at the ends of tiny quantum whirlpools within the ultracold gas.
  • The result proves experimentally that
  • structures do exist in nature
  • Physics Professor David S. Hall '91 and Aalto University (Finland)
Mars Base

Alan Guth on new insights into the 'Big Bang' - 0 views

phys.org/...03-alan-guth-insights-big.html

scibyte124 Inflation

shared by Mars Base on 22 Mar 14 - No Cached
  • Q: Can you explain the theory of cosmic inflation that you first put forth in 1980?
  • usually describe inflation as a theory of the "bang" of the Big Bang
  • describes the propulsion mechanism that drove the universe into the period of tremendous expansion that we call the Big Bang
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  • The original Big Bang theory was really a theory of the aftermath of the bang
  • described how the universe was cooled by the expansion, and how the expansion was slowed by the attractive force of gravity
  • Inflation proposes that the expansion of the universe was driven by a repulsive form of gravity.
  • According to Newton, gravity is a purely attractive force, but this changed with Einstein and the discovery of general relativity
  • General relativity describes gravity as a distortion of spacetime, and allows for the possibility of repulsive gravity
  • Modern particle theories strongly suggest that at very high energies, there should exist forms of matter that create repulsive gravity
  • Inflation
  • proposes that at least a very small patch of the early universe was filled with this repulsive-gravity material
  • During the period of exponential expansion, any ordinary material would thin out, with the density diminishing to almost nothing
  • The repulsive-gravity material actually maintains a constant density as it expands, no matter how much it expands
  • While this appears to be a
  • violation
  • of the conservation of energy, it is actually
  • consistent
  • a peculiar feature of gravity: The energy of a gravitational field is negative
  • As the patch expands at constant density, more and more energy, in the form of matter, is created
  • But at the same time, more and more negative energy appears in the form of the gravitational field that is filling the region
  • The total energy remains constant, as it must, and therefore remains very small.
  • It is possible that the total energy of the entire universe is exactly zero, with the positive energy of matter completely canceled by the negative energy of gravity
  • At some point the inflation ends because the repulsive-gravity material becomes metastable
  • decays into ordinary particles, producing a very hot soup of particles that form the starting point of the conventional Big Bang
  • point the repulsive gravity turns off, but the region continues to expand in a coasting pattern for billions of years to come
  • inflation is a prequel to the era that cosmologists call the Big Bang, although it of course occurred after the origin of the universe, which is often also called the Big Bang.
  • Q: What is the new result announced this week, and how does it provide critical support for your theory?
  • The early universe, as we can see from the afterglow of the cosmic microwave background (CMB) radiation, was incredibly uniform,
  • to have structure form at all, there needed to be small nonuniformities at the end of inflation
  • The tiny nonuniformities that did exist were then amplified by gravity
  • these nonuniformities—which later produce stars, galaxies, and all the structure of the universe—are attributed to quantum theory
  • The temperature nonuniformities in the cosmic microwave background were first measured in 1992 by the COBE satellite
  • have not generally been seen as proof of inflation, in part because it is not clear that inflation is the only possible way that these fluctuations could have been produced.
  • The stretching effect of inflation,
  • also acts on the geometry of space itself, which according to general relativity is flexible
  • Space can be compressed, stretched, or even twisted.
  • The geometry of space also fluctuates on small scales, due to the physics of quantum theory, and inflation also stretches these fluctuations, producing gravity waves in the early universe.
  • The new result,
  • is a measurement of these gravity waves, at a very high level of confidence.
  • They do not see the gravity waves directly, but instead they have constructed a very detailed map of the polarization of the CMB in a patch of the sky.
  • They have observed a swirling pattern in the polarization (called "B modes") that can be created
  • by gravity waves in the early universe
  • This is the first time that even a hint of these primordial gravity waves has been detected
  • it is also the first time that any quantum properties of gravity have been directly observed.
  • Q: How would you describe the significance of these new findings, and your reaction to them?
  • The significance of these new findings
  • help tremendously in confirming the picture of inflation.
  • As far as we know, there is nothing other than inflation that can produce these gravity waves
  • it tells us a lot about the details of inflation that we did not already know
  • it determines the energy density of the universe at the time of inflation, which is something that previously had a wide range of possibilities.
  • By determining the energy density of the universe at the time of inflation, the new result also tells us a lot about which detailed versions of inflation are still viable, and which are no longer viable
  • The current result is not by itself conclusive, but it points in the direction of the very simplest inflationary models that can be constructed.
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