Space X's Falcon 9 Rocket at Cape Canaveral, FL.

Last night space shuttle Endeavour landed after orbiting two weeks.  Space shuttle’s days are numbered as only four more flights to go until NASA will retire the aging fleet. As directed by President’s Obama’s plan to use private space enterprises to ferry humans and cargo into space, the momentum is catching on as Space X’s Falcon 9 rocket is getting ready to launch. Space X plans to send F9 on its maiden voyage as early as March. If all goes well and all the tests are successful, F9 will be able to ferry humans into space by 2013 or 2014. Very cool indeed! Here is the wiki entry for F9.

gravity waves

As a regular listener of Astronomy Cast i was intrigued to hear Pamela Gay’s description of what gravity waves are and how they behave. Her ablities to use simple analogies to describe difficult concepts at such ease really amazes me. Anyway ill try my best to describe gravity waves.

So the idea for gravitational waves is really derived from Einstein’s theories about gravity. As theorized by Einstein, large body of objects such as stars bend the space and form a gravity pool. Gravity manifests itself by bending space. Gravity waves are basically a wrinkle created in a space time continuum. Scientists have been able to detect these waves by observing stars that have exploded into a supernovae. A star that has exploded will send out waves that will cause ripples in the space time continuum. These ripples are analogous to shock waves produced when a bomb is exploded here on Earth. Very cool science. You can learn more about this from this podcast.

Stephen Hawkings explains why we haven’t been able to find life across the Milky Way. Very interesting read. Him being the smartest man alive, i am inclined to believe him.

Earth Gravity

One of the things that had baffled me for quite a while had been the gravity on our own planet. Seems silly to think about it but the question had always lingered in the back of my mind.  I understood that Earth is trapped in Sun’s orbit due to its gravity and the same relationship applies when explaining the effect of earth’s gravity on the moon. Einstein explained that the size of a massive object, such as our sun, warps the fabric of space and time around it. Planets follow the path of this warped fabric. That theory explains the gravity among stars and planets, but how does it relate to the gravity here on earth? But what exactly keeps you and me on the ground? Why do plant roots point directly toward the center of the earth? The answer comes from another force being exerted on the Earth and that force is Inertia.  This force is one of the key principles of Einstein’s theory of general relativity. Because of the amount of force being exerted on the Earth due to its acceleration around the Sun, an opposite force (gravity) is being exerted from the Earth to counter the force of Inertia. Aha!

An excerpt from Walter Isaacson book “Einstien: His life and Universe” gave an excellent visual example of this:

“A person in a closed windowless chamber who feels his feet pressed to the floor will not be able to tell whether it’s because the chamber is in outer space being accelerated upwards or because it is at rest in a gravitational field. If he pulls a penny from his pocket and lets it go, it will fall to the floor at an accelerating speed in either case. Likewise, a person who feels she is floating in a closed chamber will not know whether because the chamber is in free fall or hovering in a gravity-free region of outer space. “

To state is even more simply, the force applied when an object is resisted due to the Inertia is equal to the weight of the object. There is equivalence between all inertial effect, such as resistance to acceleration, and gravitational effects, such as weight. They are both manifestations of the same structure, which is called an Inertio-gravitational field.

Black Hole

We still don’t have a full understanding of inner workings of black holes. The idea of what is beyond the visible spectrum of the black holes as we see it has eluded some of the most prominent astrophysicists and astronomers even today.

Here is what we know : Black holes swallow everything that comes within its grasp. Even light cannot escape the massive pull of the black-holes. Black holes have an event horizon into which objects can fall into but as far as we know, nothing can come out of it. It is widely believed that every galaxy in the universe has a black-hole at the center of it.

Einstein shunned black holes as a mere mathematical curiosity. He even vigorously denied their reality. But as more and more evidence pointed toward the existence of the black holes, it is safe to say that Einstein was in denial. Einstein’s general theory of relativity dealt with a much clearer understanding of gravity than what Newton had proposed. Much of his work explained how space and time work in the fabric of space. He did little to dwell upon how the universe operates at a subatomic level. Enter Theory of Quantum Mechanics. In the mid 21^st century, few scientists were pondering on the idea of how quantum mechanics would explain the universe at the deepest level. Quantum theory dealt with the smallest particle in the universe, the atom. As more research was done on quantum theory, scientists realized that Einstein’s general theory of relativity and quantum theory were very much at odds each other. Quantum theory did not satisfy Einstein orderly equations mainly because gravity at subatomic level is non-existent. Thus the mystery of black holes became even more mysterious. Question that has eluded scientists today is whether the inner workings of a black hole follow the rules of general relativity theory or Quantum theory. Because no scientific instruments can measure what happens to particles as they go through the black hole, there isn’t any way to find the answer to the ultimate question. Several scientists have attempted to combine the two theories in hopes of deriving a grand theory, a theory of everything. Scientist think string theory may be the Holy Grail but there is still much to understand about this radical theory. I will talk more about string theory in the later post. Stay tuned!

thank you!

HT.