The Implications of Gravity in Spacetime

The theories in which modern science rest heavily upon were presented hundreds of years ago by the scientists we have grown to learn about and love. Their theories have yet to be disproved, and that is why those theories are the platform on which modern science now rests. It is a strong platform, but as it ages, we must fill in the cracks. That’s where we are at in this day and age, filling in the cracks of an old foundation. Gravity is the most fundamental force in the universe, yet it is a very weak force. The series of posts I am about to share rely heavily on our concept of Gravity, so it’s important to get the basics down first.

We will start with Galileo. In a uniform gravitational field, Galileo believed that all Galileoobjects fall identically-irrespective to their mass. To prove his theory, he climbed up the Leaning Tower of Pisa where he dropped various masses. In doing so, he proved that when an object is in free fall, it will not experience a force in relation to it’s mass and that all objects, regardless of their mass will move in the same direction, at the same time. Think of an elevator- your head and shoes will “fall” at the same time, even though your head is heavier than your shoes. Galileo gave us the understanding of inertia; where an object that is set into motion stays in motion until it is acted upon by some external force.

Aristotle believed that the Earth did not move because if you threw a ball straight up in the air it would come straight back down, instead of going to the left/right etc. Galileo argued this idea giving an example of the cabin of a ship. Inside the cabin, if there are no windows, there is no way to tell if the ship is moving or not. Galileo concluded that the laws of physics are identical in all Galilean (intertial) reference frames, providing us with our first encounter with relativity.

newton

Next, Sir Isaac Newton comes along to explain the force that acts upon all objects. Newton’s first law of motion is essentially Galileo’s concept of intertia. The second law of motion tells us that the force needed to act upon an object depends on it’s mass and acceleration. If you have a large mass with a large acceleration, you will need a large force to act upon it and so on. Finally, Newton’s third law of motion state’s that for every action, there is an equal but opposite reaction.

Newton’s laws gave us a better understanding of the physical world around us. Einstein decided to apply his idea’s to the entire universe. On November 25th, 1915 Einstein
published his Theory of Special Relativity. This theory has Einsteinprovided us a profound understanding of our universe, and much of what we know has been found using Einstein’s theories. Special Relativity tells us that the speed of light is the same in all constantly moving frames and that Time slows down the faster you travel and vice versa.

To better understand the idea of special relativity, I will provide an analogy from the book “Hyperspace” by Michio Kaku: Continue reading “The Implications of Gravity in Spacetime”

Background

I randomly signed up for an online physics course that would last six weeks. Little did I know, I would become so intrigued by the end that I am now spending every spare second reading science blogs, science books, and re-watching the lectures of the course. I plan to share with whomever takes the time to read this, the exciting new things that I learned from the course.

Let me start with an introduction about the course.

The title of the course was “Gravity! From the big bang to black holes.” So, as you may assume, the topics ranged from Einstein’s general relativity, the big bang, inflation, dark matter, dark energy, gravitational waves, and black holes. Some old concepts, some new (to me). The best thing about the course was that you did not need to have any background in physics. Just an appetite for learning, and maybe some extra research on your own time if interested.

The course was taught by Professor Pierre Binetruy of Paris Diderot University. Pierre was the first director of the AstroParticle and Cosmology laboratory in Paris upon it’s creation. His main interests, according to a bio online, include cosmology and gravitation; connecting the theories of the early universe and fundamental interactions. He’s highly knowledgeable about inflation models, dark energy, and cosmological background of gravitational waves. Due to these areas of interest, he is highly involved in the eLisa mission- which I will go into more detail about later on.

I would just like to express how happy I am about taking this class. The course provided such lucid, comprehensible explanations on theories and concepts of physics. There was hardly any math involved, which was nice. The detailed explanations and demonstration’s made these unfamiliar concepts easy to grasp. Finally, Pierre arranged live hangouts where we were introduced to prestigious scientists, and we were able to ask questions during a live chat. George Smoot was one scientist that was present during the hangouts, and also recorded a lecture himself to explain the concept that won him the Nobel Prize in 2006. We were also able to meet key scientists that were actively involved in the LISAPathfinder mission, which was launched 12/03/2015. This mission will (hopefully) uncover another corner of the veil on the universe. I now anxiously await the discoveries that will be made from this mission. The series of blog posts that follow should explain why.

Here I will post the links to the series of posts I will be writing:

  1. The Implications of Gravity in Spacetime
  2. Waves of Spacetime- GW150914
  3. Black Holes: Part I