LHC collides ions at new record energy

LHC restart ..

After the successful restart of theLarge Hadron Collider (L fiths of data taking with proton collisions at a new energy frontier, the LHC is moving to a new phase, with the first lead-ion collisions of season 2 at an energy about twice as high as that of any previous collider experiment. Following a period of intense activity to re-configure the LHC and its chain of accelerators for heavy-ion beams, CERN’s accelerator specialists put the beams into collision for the first time in the early morning of 17 November 2015 and ‘stable beams’ were declared at 10.59am today, marking the start of a one-month run with positively charged lead ions: lead atoms stripped of electrons. The four large LHC experiments will all take data over this campaign, includingLHCb, which will record this kind of collision for the first time. Colliding lead ions allows the LHC experiments to study a state of matter that existed shortly after the big bang, reaching a temperature of several trillion degrees.

Lead ions collide in the ALICE detector 

“It is a tradition to collide ions over one month every year as part of our diverse research programme at the LHC,” said CERN Director-General Rolf Heuer. “This year however is special as we reach a new energy and will explore matter at an even earlier stage of our universe.”

Early in the life of our universe, for a few millionths of a second, matter was a very hot and very dense medium – a kind of primordial ‘soup’ of particles, mainly composed of fundamental particles known as quarks and gluons. In today’s cold Universe, the gluons “glue” quarks together into the protons and neutrons that form bulk matter, including us, as well as other kinds of particles.

“There are many very dense and very hot questions to be addressed with the ion run for which our experiment was specifically designed and further improved during the shutdown,” saidALICE collaboration spokesperson Paolo Giubellino. “For instance, we are eager to learn how the increase in energy will affect charmonium production, and to probe heavy flavour and jet quenching with higher statistics. The whole collaboration is enthusiastically preparing for a new journey of discovery.”

Lead ions collide in the LHCb detector 

Increasing the energy of collisions will increase the volume and the temperature of the quark and gluon plasma, allowing for significant advances in understanding the strongly-interacting medium formed in lead-ion collisions at the LHC. As an example, in season 1 the LHC experiments confirmed the perfect liquid nature of the quark-gluon plasma and the existence of “jet quenching” in ion collisions, a phenomenon in which generated particles lose energy through the quark-gluon plasma. The high abundance of such phenomena will provide the experiments with tools to characterize the behaviour of this quark-gluon plasma. Measurements to higher jet energies will thus allow new and more detailed characterization of this very interesting state of matter.

“The heavy-ion run will provide a great complement to the proton-proton data we've taken this year," said ATLAS collaboration spokesperson Dave Charlton. "We are looking forward to extending ATLAS' studies of how energetic objects such as jets and W and Z bosons behave in the quark gluon plasma.”

Lead ions collide in the ATLAS dectector 

The LHC detectors were substantially improved during the LHC’s first long shutdown. With higher statistics expected, physicists will be able to look deeper at the tantalising signals observed in season 1.

"Heavy flavour particles will be produced at high rate in Season 2, opening up unprecedented opportunities to study hadronic matter in extreme conditions,” saidCMS collaboration spokesperson Tiziano Camporesi. « CMS is ideally suited to trigger on these rare probes and to measure them with high precision. »

For the very first time, the LHCbcollaboration will join the club of experiments taking data with ion-ion collisions.

"This is an exciting step into the unknown for LHCb, which has very precise particle identification capabilities. Our detector will enable us to perform measurements that are highly complementary to those of our friends elsewhere around the ring,” 

©2015-TASA

Extra dimensions, gravitons, and tiny black holes

100 years to Relativity

Why is gravity so much weaker than the other fundamental forces? A small fridge magnet is enough to create an electromagnetic force greater than the gravitational pull exerted by planet Earth. One possibility is that we don’t feel the full effect of gravity  because part of it spreads to extra dimensions. Though it may sound like science fiction, if extra dimensions exist, they could explain why the universe is expanding faster than expected, and why gravity is weaker than the other forces of nature.

A question of scale

In our everyday lives, we experience three spatial dimensions, and a fourth dimension of time. How could there be more? Einstein’s general theory of relativity tells us that space can expand, contract, and bend. Now if one dimension were to contract to a size smaller than an atom, it would be hidden from our view. But if we could look on a small enough scale, that hidden dimension might become visible again. Imagine a person walking on a tightrope. She can only move backward and forward; but not left and right, nor up and down, so she only sees one dimension. Ants living on a much smaller scale could move around the cable, in what would appear like an extra dimension to the tightrope-walker.

How could we test for extra dimensions? One option would be to find evidence of particles that can exist only if extra dimensions are real. Theories that suggest extra dimensions predict that, in the same way as atoms have a low-energy ground state and excited high-energy states, there would be heavier versions of standard particles in other dimensions. These heavier versions of particles – called Kaluza-Klein states – would have exactly the same properties as standard particles (and so be visible to our detectors) but with a greater mass. If CMS orATLAS were to find a Z- or W-like particle (the Z and W bosons being carriers of the electroweak force) with a mass 100 times larger for instance, this might suggest the presence of extra dimensions. Such heavy particles can only be revealed at the high energies reached by theLarge Hadron Collider (LHC).

A little piece of gravity?

Some theorists suggest that a particle called the “graviton” is associated with gravity in the same way as the photon is associated with the electromagnetic force. If gravitons exist, it should be possible to create them at the LHC, but they would rapidly disappear into extra dimensions. Collisions in particle accelerators always create balanced events – just like fireworks – with particles flying out in all directions. A graviton might escape our detectors, leaving an empty zone that we notice as an imbalance in momentum and energy in the event. We would need to carefully study the properties of the missing object to work out whether it is a graviton escaping to another dimension or something else. This method of searching for missing energy in events is also used to look for dark matter or supersymmetric particles.

Microscopic black holes

Another way of revealing extra dimensions would be through the production of “microscopic black holes”. What exactly we would detect would depend on the number of extra dimensions, the mass of the black hole, the size of the dimensions and the energy at which the black hole occurs. If micro black holes do appear in the collisions created by the LHC, they would disintegrate rapidly, in around 10^-27 seconds. They would decay into Standard Model or supersymmetric particles, creating events containing an exceptional number of tracks in our detectors, which we would easily spot. Finding more on any of these subjects would open the door to yet unknown possibility.

The Hubble Story

In the Beginning

Since the dawn of civilization, man was limited by his vision and imagination about his understanding of the universe. The telescope enhanced his vision and tempered his pride, as observations by Copernicus, Galileo and Kepler in the 16th and 17th centuries A.D. rebuffed the millennia-old conceit that the Earth is the center of the universe, spearheading the Scientific Revolution.

By the 18th century, the telescope would become the indispensable instrument for investigations of the cosmos. Bigger and better telescopes were built all over the world. Planets, stars, and nebulae which could not be seen by the naked eye were now being routinely noted and logged. Advances in spectroscopy, photography, and photometry increased telescope versatility, sensitivity, and discovery power.

Enter Edwin Hubble

By the turn of the 20th century, most astronomers believed that the observable universe consisted of one galaxy, our Milky Way Galaxy, an oasis of stars, dust, and gas in the vastness of space. However, in 1924, American astronomer Edwin Hubble used the 100-inch Hooker Telescope (see image below) on Mount Wilson near Los Angeles, California, to observe billions of other galaxies besides our own Milky Way, almost all moving away from each other. This suggested that the universe is expanding, unleashing a Pandora's box of seminal inquiries—such as the Big Bang theory—about the possible beginning and end of the universe—issues which are still being debated to this day.

Astronomers like Edwin Hubble (before and after his time), toiled long, frigid nights inside enormous dome-shaped "observatories" pointing their telescopes skyward, yearning for the best possible snapshot of the heavens. However they faced a major obstacle that stood between them and a clear view of the universe: the Earth's atmosphere. The Earth's atmosphere is a fluid, chaotic soup of gas and dust. It blurs visible light, causing stars to twinkle and making it difficult to see faint stars. It hinders or even totally absorbs other wavelengths of light, making observations of such wavelength ranges as infrared, ultraviolet, gamma rays and X-rays difficult or virtually impossible (it is also these properties which protect us from the harmful effect of these rays).

Observatories with the largest of telescopes in various continents have been perched upon mountain tops and away from distracting city lights, from Caucasus Mountains in Europe to the Australian outback, with varying levels of success. Adaptive optics and other image processing techniques have minimized - but not totally eliminated - the effects of the atmosphere.

A Telescope in Space?

In 1923, German scientist Hermann Oberth, one of the three fathers of modern rocketry (Oberth, Robert Goddard and Konstantin Tsiolkovsky), published "Die Rakete zu den Planet engrained" ("The Rocket into Planetary Space"), which mentioned how a telescope could be propelled into Earth orbit by a rocket. In 1946, Princeton astrophysicist Lyman Spitzer wrote about the scientific benefits of a telescope in space, above Earth's turbulent atmosphere.

Following the launch of the Soviet satellite Sputnik in 1957, the fledgling National Aeronautics and Space Administration (NASA) successfully launched two Orbital Astronomical Observatories (OAOs) into orbit. They made a number of ultraviolet observations and provided learning experiences for the manufacture and launch of future space observatories.

The LST - Large Space Telescope
Meanwhile, scientific, governmental, and industrial groups planned the next step beyond the OAO program. Spitzer gathered the support of other astronomers for a "large orbital telescope" and addressed the concerns of its critics. In 1969, the National Academy of Sciences gave its approval for the Large Space Telescope (LST) project, and the hearings and feasibility studies continued.

After Armstrong's "giant leap for mankind" on the moon in 1969, funding for NASA space programs began to dwindle, putting the LST program in jeopardy. LST planners had to design the telescope under budget constraints. A number of downsizing measures were weighed and considered: decrease the size of the primary mirror, the number of scientific instruments, the diameter of the Systems Support Module and the number of spare parts created and tests performed. In 1974, the LST Science Working Group recommended the space telescope carry a large complement of interchangeable instruments. They would have specifications to resolve at least one-tenth of an arcsecond, and have a wavelength range from ultraviolet through visible to infrared light.
The Space Shuttle NASA and its industrial partners—called contractors—brought up the option of developing a vehicle that could achieve orbit and return to earth intact and be reused repeatedly; the concept of the Space Shuttle was born. The Space Shuttle could deploy the LST into space and reel it back for return to Earth.

NASA suggested that the lifetime of the space telescope be fifteen years, which implied that the instruments needed the ability to be replaced on the ground or even serviced in orbit—an ability not afforded to any satellite before or since. Scientists also had to balance the size and quantity of scientific instruments versus their cost. Too many instruments meant financial support was less likely; conversely, instruments of minimal capability would result in the loss of scientific support for the telescope. The European Space Agency (ESA) joined the project in 1975 and provided fifteen percent of the funding of the LST via contribution of the Faint Object Camera (FOC) and the solar arrays. In return, NASA guaranteed at least fifteen percent of telescope time—the amount of time astronomers use the telescope for space observations - to European astronomers. In 1977, Congress approved funding to build one of the most sophisticated satellites ever constructed.

Who Does What?

NASA chose Marshall Space Flight Center in Huntsville, Alabama, as the lead NASA field center for the design, development, and construction of the renamed Space Telescope (ST). Marshall delegated Perkin-Elmer Corporation (now, Hughes Danbury Optical Systems) the task of developing the Optical Telescope Assembly and the Fine Guidance Sensors. Lockheed Missiles and Space Company (now, Lockheed Martin) was selected by Marshall to build the cylindrical casing and the internal support systems (the Support Systems Module) and assembling the telescope together.

NASA chose Goddard Space Flight Center in Greenbelt, Maryland, to be the lead in scientific instrument design and ground control for the space observatory. Scientists were organized into "Instrument Definition Teams" which would translate scientific aims into scientific devices and incorporate them into the space telescope housing. After an announcement was made to the astronomy community, proposals were received and judged, and five devices were selected as the initial instruments that would be aboard the Space Telescope: the Faint Object Camera, the Wide Field/Planetary Camera, the Faint Object Spectrograph, the High Resolution Spectrograph, and the High Speed Photometer.

The Johnson Space Center in Houston, Texas, and the Kennedy Space Center in Florida supplied Space Shuttle support. In all, dozens of contractors, a handful of universities, and several NASA centers, spanning 21 states and 12 other countries worldwide, made the dream of a telescope above the clouds and in space a reality.

In 1983, the Space Telescope Science Institute (STScI) was established at The Johns Hopkins University in Baltimore, Maryland. The staff of STScI evaluated proposals for telescope time and managed the resulting telescope observations. A number of delays stemming from underestimating the costs and engineering requirements of the state-of-the-art telescope caused the launch date to be moved from December 1983 to the second half of 1986. NASA re-examined interfaces, instruments, and assemblies. The building of the Optical Telescope Assembly encountered engineering challenges. Scientific instruments, like the Wide Field/Planetary Camera (WF/PC), underwent redesign, removing weight and redundancy.

Hubble is Born

In regards to the maintenance and upgrading of the space telescope, plans were made to conduct servicing missions in orbit versus returning the telescope to Earth and refurbishing it on the ground. It was an innovative concept that would be even easier on a budget. In the midst of this spirit of renovation, the Space Telescope was renamed the Hubble Space Telescope (HST). By 1985, the telescope was assembled and ready for launch.

However, in 1986 disaster struck. The Challenger accident forced NASA to ground the Space Shuttle fleet for two years. However, these were years well spent by the HST Project. Solar panels were improved with new solar cell technology. The aft shroud was modified to make instrument replacement during servicing easier. Computers and communication systems were upgraded. The HST was subjected to further stress tests in the harsh environments of liftoff and space.

Finally, on April 24, 1990, the Space Shuttle Discovery lifted off from earth with the Hubble Space Telescope nestled securely in its bay. The following day, Hubble was released into space, ready to peer into the vast unknown of space, offering mankind a glimpse upon distant, exotic cosmic shores yet to be described.

For more info :
NASA

©2015-TASA

Protein complex may help explain magnetic sensing in insects and animals

(TASA)—A team of researchers with Peking University, the Chinese Academy of Sciences and Tsinghua University has identified a protein that aligns with a magnetic field when polymerized and coupled with another well known protein. In their paper published in the journal Nature Materials, the researchers suggest the protein complex may be the means by which many insects and animals orient themselves using the Earth's magnetic field.

Scientists have studied animals, such as homing pigeons, that are able to use the Earth's magnetic field to orient themselves, for quite some time, but have yet to uncover the actual mechanism behind the ability. In this new work, the researchers believe they may have found the underlying chemistry, even if they have not been able to connect it directly to magnetic sensing.

The researchers picked up where other research left off—with a light sensing protein called cryptochrome that has been identified in the eyes of some animals–some have suggested it may play a part in magnetic sensing. But, because the protein is not sensitive to magnetism, the team reasoned that it might team up with another protein that is. To find out, they searched the genome of a fruit fly that is known to sense magnetic fields, until they found a gene responsible for creating a protein (called CG8198, which they renamed to MagR) that would respond to iron. They then polymerized that protein and coupled it with cryptochrome and then watched, using a microscope, what happened when iron objects were brought near. The team reports that the protein complex lined up like a needle in a compass.

The researchers acknowledge that their findings do not prove that the protein complex is responsible for magnetic sensing, but suggest it seems possible—if the protein complex lined up inside the eye of a pigeon, for example, it could cause a reaction with other proteins or even cells, that in turn could impact nerve cells. They note that theprotein complex exists in many organisms that have demonstrated magnetic sensing, including in the eyes of pigeons—they are calling on the research community to conduct other studies to determine if removing the complex from magnetic sensing insects or animals, causes them to lose their magnetic sensing abilities, which could indirectly prove that they form the basis for the ability. If such efforts prove fruitful, then the next logical step would be to study the complex further as it exists inside living animals to determine exactly how it works.

Abstract : 
The notion that animals can detect the Earth's magnetic field was once ridiculed, but is now well established. Yet the biological nature of such magnetosensing phenomenon remains unknown. Here, we report a putative magnetic receptor (Drosophila CG8198, here named MagR) and a multimeric magnetosensing rod-like protein complex, identified by theoretical postulation and genome-wide screening, and validated with cellular, biochemical, structural and biophysical methods. The magnetosensing complex consists of the identified putative magnetoreceptor and known magnetoreception-related photoreceptor cryptochromes (Cry), has the attributes of both Cry- and iron-based systems, and exhibits spontaneous alignment in magnetic fields, including that of the Earth. Such a protein complex may form the basis of magnetoreception in animals, and may lead to applications across multiple fields.

© 2015 : TASA

Faraday's law

Data storage in Crystal quartz will change everything !!!

There’s a new type of storage device which many tech corporations have been diving into in secret for the past few years, which Hitachi newly came out with a technology they are developing which is fundamentally a sheet of Quartz Glass, which could possibly save data for up to 300 Million Years!

If you didn’t know anything about storage devices that we at present have, but anything from records, CD’s, USB sticks, magnetic tape, none of these can even lay a finger on this new, very inspiring technology.

“The prototype is made of a square of quartz two centimeters wide and two millimeters thick. It houses four layers of dots that are made with a femtosecond laser, which yields very short pulses of light. The dots represent information in binary form, a standard that should be comprehensible even in the distant future and can be read with a basic optical microscope. Since the layers are embedded, surface erosion would not affect them.”

Now, while this is thrilling, there’s more to it than just that. See, While Hitachi presently has a real produceable thing which they will possibly start marketing once they figure out a simple means of relocating data to say, computers and television, the basic model they have (see picture above) only has the data storage volume somewhat better than a CD.

But that’s not to say that this tech is doomed, simply that it’s young… and even then, some people are by now working on a larger and better thing!

Researchers in the University of Southampton in the UK have been developing an even MORE unbelievable technology. It’s called “Superman” Crystals, and possibly has the storage volume of up to 350 TB, and can last forever!

Below: A graphic depicting a 5D optical storage writing setup: femtosecond laser, spatial light modulator (SLM), Fourier lens (FL), half-wave plates matrix (»/2 M), dichroic mirror, 1.2 NA water immersion objective, silica glass sample, translation stage. (Image: University of Southhampton.

“The researchers used a femtosecond laser, which produces pulses of light in femtoseconds (one quadrillionth, or one millionth of one billionth of a second). The 5D read/write laser can record up to a projected 360 TB/disc data capacity on nano-structured glass proficient of thermal stability up to 1000°C — and an almost unlimited lifetime. The information encoding comes in five dimensions that comprise of the size and orientation in addition to the three dimensional position of these nano-structures.”

It appears Crystals still got some magic after all. And they don’t have to just be in your pocket, they might be the basis for all of our computers in the future. I mean, they are now, but possibly even more so.

The Crystal Skulls

You’ve all heard of the ancient crystal skulls and the stories that they apparently hold a repository of knowledge. Well, the researchers at hitachi may have just revived an ancient advanced technology. It has been said throughout history that the crystal skulls contain ancient knowledge probably dating back to the time of Atlantis, or even further.

Information on a grand scale. The skulls are said to have the answers to human evolution, universal information, planetary information, and most prized of all, humankind’s destiny and true purpose. The legend claims that at a time of great need, the skulls will be found and reunited. The information they deliver will save the human race. The legend forewarns, though, that mankind must be able to accept the knowledge morally and spiritually.

This data can apparently exist forever, enduring great temperatures and hostile conditions without degrading… at least until the sun starts to die and expands to consume the earth, that is.

Hitachi scientist Kazuyoshi Torii said that quartz glass is extremely stable and resilient material, used to make beakers and other instruments for laboratory use. Due to the medium, the chip is waterproof, resilient to many chemicals and unaffected by radio waves. Even more, it can be exposed directly to high temperature flames and heated to 1,832 Fahrenheit for at least two hours without being spoiled.

“We trust data will survive unless this hard glass is broken,” said senior scientist Takao Watanabe.

Rather than storing precious information for mankind in an ordinary piece of quartz that could have been lost in time, the ancients chose to store their wisdom in a vessel shaped like a human head. These would be used in many rituals and ceremonies, and passed down from generation to generation. In the same way that our human skull guards and holds the brain, a crystal skull is a mind-like container that holds a generational library of knowledge – from ancient history to a blueprint of possible futures.

100 Years of the General Theory of Relativity

100 Years of the General Theory of Relativity

It was 100 years ago this month that Einstein delivered four lectures to the Prussian Academy of Sciences in Berlin, which culminated in his discovery of the general theory of relativity.

Einstein’s determined pursuit of mathematical equations that describe how the force of gravity works remains one of the most influential scientific discoveries of all time.

If you’re planning a party — a general relativity rave, maybe — November 25th is the day it all came together. That’s a Wednesday. But a Thanksgiving toast at dinner the next day works well, too.

To celebrate, physicist Brian Greene looks back on the intellectual and emotional journey Einstein took to arrive at the general theory of relativity in an article in Smithsonian Magazine. In March, Greene joined neurologist Frederick Lepore and filmmaker Thomas Levenson during the 92Y’s 7 Days of Genius Festival for a conversation about what made Einstein such a talented scientist. The conversation is moderated by Cynthia McFadden of NBC News.

If you still have room for more Einstein, the 2015 World Science Festival brought together Gabriela González, Samir Mathur, Andrew Strominger, Cumrun Vafa, Steven Weinberg and Brian Greene to discuss Reality Since Einstein.

India's GSAT-15 Communication Satellite Launched Successfully

GSAT-15, India’s latest communications satellite, was launched successfully by the European Ariane 5 VA-227 launch Vehicle in the early morning hours of today (November 11, 2015).  The 3164 kg GSAT-15 carries communication transponders in Ku-band as well as a GPS Aided GEO Augmented Navigation (GAGAN) payload operating in L1 and L5 bands.

After a smooth countdown lasting 11 hours and 30 minutes, the Ariane 5 launch vehicle lifted off right on schedule at 0304 hrs (3:04 am) IST today. After a flight of  43 minutes and 24 seconds, GSAT-15 separated from the Ariane 5 upper stage in an elliptical Geosynchronous Transfer Orbit (GTO) with a perigee (nearest point to Earth) of 250 km and an apogee (farthest point to Earth) of 35,819 km, inclined at an angle of 3.9 degree to the equator.  The achieved orbit was very close to the intended one.

ISRO's Master Control Facility (MCF) at Hassan in Karnataka took over the command and control of GSAT-15 immediately after its separation from the launch vehicle. Preliminary health checks of the satellite revealed its normal health.

In the coming days, orbit raising manoeuvres will be performed to place the satellite in the Geostationary Orbit (36,000 km above the equator) by using the satellite’s propulsion system in steps.

After the completion of orbit raising operations, the two solar arrays and both the antenna reflectors of GSAT-15 will be deployed.  Following this, the satellite will be put in its final orbital configuration.  GSAT-15 will be positioned at 93.5 deg East longitude in the geostationary orbit along with the operational INSAT-3A and    INSAT-4B satellites. Later, it is planned to experimentally turn on the communication payloads of GSAT-15. After the successful completion of all the in-orbit tests,   GSAT-15 will be ready for operational use.  

Is time travel possible?

Time travel is one of my favorite topics! I wrote some time travel stories in junior high school that used a machine of my own invention to travel backwards in time, and I have continued to study this fascinating concept as the years have gone by.
We all travel in time. During the last year, I've moved forward one year and so have you. Another way to say that is that we travel in time at the rate of 1 hour per hour.
But the question is, can we travel in time faster or slower than "1 hour per hour"? Or can we actually travel backward in time, going back, say 2 hours per hour, or 10 or 100 years per hour?
It is mind-boggling to think about time travel. What if you went back in time and prevented your father and mother from meeting? You would prevent yourself from ever having been born! But then if you hadn't been born, you could not have gone back in time to prevent them from meeting.
The great 20th century scientist Albert Einstein developed a theory called Special Relativity. The ideas of Special Relativity are very hard to imagine because they aren't about what we experience in everyday life, but scientists have confirmed them. This theory says that space and time are really aspects of the same thing—space-time. There's a speed limit of 300,000 kilometers per second (or 186,000 miles per second) for anything that travels through space-time, and light always travels the speed limit through empty space.
Special Relativity also says that a surprising thing happens when you move through space-time, especially when your speed relative to other objects is close to the speed of light. Time goes slower for you than for the people you left behind. You won't notice this effect until you return to those stationary people.
Say you were 15 years old when you left Earth in a spacecraft traveling at about 99.5% of the speed of light (which is much faster than we can achieve now), and celebrated only five birthdays during your space voyage. When you get home at the age of 20, you would find that all your classmates were 65 years old, retired, and enjoying their grandchildren! Because time passed more slowly for you, you will have experienced only five years of life, while your classmates will have experienced a full 50 years.
So, if your journey began in 2003, it would have taken you only 5 years to travel to the year 2053, whereas it would have taken all of your friends 50 years. In a sense, this means you have been time traveling. This is a way of going to the future at a rate faster than 1 hour per hour.
Time travel of a sort also occurs for objects in gravitational fields. Einstein had another remarkable theory called General Relativity, which predicts that time passes more slowly for objects in gravitational fields (like here on Earth) than for objects far from such fields. So there are all kinds of space and time distortions near black holes, where the gravity can be very intense.
In the past few years, some scientists have used those distortions in space-time to think of possible ways time machines could work. Some like the idea of "worm holes," which may be shortcuts through space-time. This and other ideas are wonderfully interesting, but we don't know at this point whether they are possible for real objects. Still the ideas are based on good, solid science. In all time travel theories allowed by real science, there is no way a traveler can go back in time to before the time machine was built.
I am confident time travel into the future is possible, but we would need to develop some very advanced technology to do it. We could travel 10,000 years into the future and age only 1 year during that journey. However, such a trip would consume an extraordinary amount of energy. Time travel to the past is more difficult. We do not understand the science as well.
Actually, scientists and engineers who plan and operate some space missions must account for the time distortions that occur because of both General and Special Relativity. These effects are far too small to matter in most human terms or even over a human lifetime. However, very tiny fractions of a second do matter for the precise work necessary to fly spacecraft throughout the solar system.
 

Is it possible to point to a direction in the sky and say "that way is the center of the universe, where the Big Bang started?" If not, why not?

Our friends in the CATO Rocketry Club in Gales Ferry, Connecticut, wonder whether it is possible to point to a direction in the sky and say "that way is the center of the universe, where the Big Bang started."
The "center of the universe" has always been a very important idea for humans. Just as a new baby might think he or she is at the center of the universe, for thousands of years people saw Earth as the center of the cosmos. Some ancient Greeks thought the universe was made of two spheres: one of the spheres was Earth, and the other was the sky, which surrounded Earth and was studded with stars.
In the 1500s, the Polish astronomer Nicolaus Copernicus had a better idea—although still wrong—for explaining the motion of the planets through the night sky. He thought that the Sun was actually the center of the universe, with Earth and the other planets circling the Sun. However, the sphere of stars surrounding the solar system remained as part of his idea.
Now we know that not only are we humans not at the center of the universe, but there is no center of the universe!
The Big Bang is the name scientists give to the events that started the universe. The Big Bang is often described as a huge explosion. But the problem with that picture is that an explosion has a central point where it starts, such as a bomb or a spark. The Big Bang wasn't like that, but an explosion is the closest thing in our everyday experience to help us understand it.
The Big Bang cannot have happened at a particular place in the universe, because before the Big Bang there was no universe! The Big Bang happened everywhere at once, about 14 billion years ago, bringing space and time into existence. The Big Bang kicked off a rapid expansion of space, and space has been expanding ever since.
If we had a powerful telescope that could see all the way to the end of the universe, would we find more of the universe on one side of Earth than on the other? No. We would find that it looks the same in all directions. So does that mean we are still at the center of the universe? Well, no, it doesn't.
Imagine that you are one of many tiny pencil marks on a balloon. You can see only in a line across the balloon's surface—not into or out of the balloon. No matter which way you look, the end of your world seems to be the same distance from you. But that doesn't mean you are at the center of this little world! If you start moving across the surface of the balloon, it would still look as if you were at the center of the world, but the fact is that your two-dimensional world has no center.
Now, suppose your balloon world is being inflated with air. All the other pencil marks will be getting farther and farther away from you as the balloon gets bigger. In fact, all pencil marks get farther from each other, so no matter where you are, it looks as if you are at the center of the expansion. Although it may be hard to imagine that happening in space, the expansion of our three-dimensional universe is similar. Space itself is curved, so as the universe expands from the Big Bang, it is somewhat like the two-dimensional space on a balloon. But just like the surface of that balloon, there is no center in the universe.
One of the ways scientists know the Big Bang happened is that they have been able to see the faint radiation left over from shortly after this cosmic birth. In a remarkable scientific accomplishment, they predicted what this radiation would look like. Other scientists found the radiation using a special telescope, and as more measurements have been made from Earth and from space, the Big Bang has continued to provide an excellent description of how the universe has evolved.