th reader.Why speed of light ? Well, the aim of this blog is to reach the impossible by exploration and scientific fervor. Exploration never ends, knowledge never dies but Speed of Light can be achieved ....
Two NASA officials who deemed a July 1 launch for the space shuttle Discovery too risky without alterations, said they would not oppose the launch schedule approved by NASA chief Michael Griffin. "At this point it's a done deal. We now go forward and we look to see if we can launch this vehicle next week," Bryan O'Connor, the National Aeronautics and Space Administration's top safety official told a telephone news conference Wednesday.
Human activity has made Earth hotter now than at any point in 400 and possibly more than 1000 years, a US Congress commissioned report said Thursday.
Temperature in the northern hemiphere warmed by about one degree Fahrenheit (0.6 degrees Celsius) during the last century, the report by the National Academy of Sciences found.
Scientists have argued that the change was sufficient to alter hurricane patterns and see Polar ice caps melt down.
"There is sufficient evidence ... to say with a high level of confidence that the last few decades of the 20th century were warmer than any comparable period in the last 400 years," the academy's National Research Council report said.
The Republican-led House Science Committee commissioned the study in November after controversial findings by climatologist Michael Mann showed that the 1990s were the warmest decade and 1998 the warmest year of the 20th century.
The latest report -- while stressing that data from before 1600 is for the large part sketchy -- said Mann's conclusion that a graphic charting temperatures over the past century looked like a "hockey stick" was correct.
The academy's National Research Council said Mann's findings were "plausible," but that there was insufficient evidence to pinpoint 1998 as the hottest year.
Existing data did illustrate that temperatures were lower before the industrial revolution and that human activity was responsible for the warming, the study said.
For the northern hemisphere, reconstructions showed that warm conditions centered around the year 1000 and that a relatively cold period -- dubbed the "Little Ice Age" -- followed from 1500 to 1850.
Things started heating up again with the industrial revolution before spiking up in the past decades.
Although temperatures 1,000 years ago were warm, they do not compare with those now, the report said. "None of the reconstruction indicates that temperatures were warmer during medieval times than during the past few decades," it said.
The report called for more research into proxy data for the period prior to 1600 so that comparisons for the past two millennia could be made, and for improved global access to existing to information on which temperature studies could be conducted.
It noted that far more research existed for the northern hemisphere than for the southern hemisphere, and that this vacuum limited the reliability of data overall.
The term “Black Hole” is of very recent origin coined by John Wheeler, an American scientist.
The graphical description and idea of “A BLACK HOLE” goes back to two hundred years when there were two prevalent and widely accepted theories about light. Light was considered to possess two forms (or natures) namely particle and wave nature. The particle nature of light was favored by Newton.
According to the wave nature, light behaves as a wave. The question that arises is that – Can gravity affect light ? Yes, gravity can affect light if it is considered to behave as particle. Roemer discovered that light has a finite speed, therefore, gravity must have important effect on it.
Gravity is seen to have effect on cricket balls, humans and rockets etc. But light is composed of photons. Photon is a particle which can move upwards constantly against gravity without showing retarding effect. How can then Newtonian gravity affect light?
A star is formed when a light amount of hydrogen starts to collapse on itself due to strong gravitational pull. Eventually due to gravity and increasing pressure the gases heat up and finally hydrogen atoms collide to form helium. The heat released in the process makes the star shine.
Oppenheimer’s work was based on black holes.
He proposed that gravitational field of the star changes the path of light rays it emits in space-time. The light cones are bent slightly inwards near the surface of star. As the star passes its years of life, it contracts and its gravitational field becomes stronger and stronger and finally a time comes when the light cones bend inwards so much that it can no longer escape. This results into nothing but a region in universe which is called a black hole.
The boundary of a black hole is called event horizon. It coincides with the path of light rays that just fail to escape from the black hole.
Earth is about to pass through a stream of dust from Halley's Comet, and this will produce the annual eta Aquarid meteor shower. The shower peaks on Saturday, May 6th, with 10 meteors per hour in the northern hemisphere and as many as 60 meteors per hour in the southern hemisphere. The best time to look is during the hours immediately before sunrise on Saturday morning.
PHOTO OP: On May 7th, the biggest fragment of dying comet 73P/Schwassmann Wachmann 3 will glide by the Ring Nebula in Lyra. The view through backyard telescopes should be wonderful. This is an opportunity for astrophotographers to take some rare photos of a comet and a planetary nebula side by side.
Visit http://spaceweather.com for sky maps and more information.
We have a unique position in the universe. While we observe from our planet, universe seems to be same from all directions. In 1965,Penzias and Robert Wilson, were testing a very sensitive microwave detector. They found that their detector was picking up more noise than it ought to. The noise did not appear to be coming from any particular direction. It was concluded after sometime that the noise was from outside the atmosphere. Infact, it was coming from beyond the solar system.
When one combines general relativity with the uncertainty principle of quantum mechanics, it is possible for both space and time to be finite without any edges or boundaries.
