Interstellar Travel

In many science fiction movies, spaceships race through the galaxy at extremely high speeds, seemingly ignoring many of nature’s laws that govern our universe. With what we know about the universe right now, it is impossible for any object to travel faster than the speed of light. Any man made object has not reached speeds even close to the speed of light, as the five planetary probes that we have launched to eventually travel among the stars move at speeds less than 1/10,000 of the speed of light. Alpha Centauri is the closest star system to Earth, but it is still a staggering 4.3 light years away. Therefore, at the rate that these probes are traveling, it would take each of these probes at least 100,000 to reach Alpha Centauri, but their trajectories won’t take them anywhere close to it. Rather, these probes will simply continue their journey through interstellar space for millions or billions of years to come.

If we wanted to travel to other stars within human lifetimes, we would need starships that are able to travel at speeds close to the speed of light. In order to do this, we would need entirely new types of engines built to travel at such high speeds. Similarly, spaceships traveling at such high speeds would require new types of shielding to protect crew members from instant death, as a spaceship traveling through interstellar space near the speed of light would be bombarded by billions of deadly high-energy cosmic rays. Even if we were able to accomplish this, we would still be met with other significant challenges. According to Einstein’s theory of relativity, time moves much slower to an object traveling near the speed of light. For instance, a starship embarking on a 50-light-year round trip to the star Vega would only take crew members about 2 years, but more than 50 years would have passed on Earth while they were gone. While the crew would have only aged two years, they would return to a considerably different world that they left. Therefore, it is clear that we are years away from interstellar space travel within human lifetimes, and even if are able to accomplish this we would still face other immense challenges.

Voyager 2 a space probe that has reached interstellar space

The Drake Equation

We hear about aliens all the time, whether in books or movies or tv shows, and this leads us to ponder our own existence. Are we alone, or is there other life out there? This is a question that has plagued mankind since begun exploring interstellar space, and started looking for life in our own Solar System. If it turns out that life is actually out there, it is natural to wonder if there is other intelligent life in the universe. Would there be other human civilizations, or is Earth the only planet in the entire universe that harbors intelligent life, and we really are all alone. And even if there are other human civilizations out there, how would we find them? Scientists now speculate that we might be able to detect other civilizations simply by listening for signals that they are sending into interstellar space. By this method, efforts to search for extraterrestrial intelligence can only succeed if advanced civilizations are broadcasting signals right now.

The astronomer Frank Drake wrote a simple equation that summarizes factors that would determine the number of civilizations we might be able to contact. This equation, known formally as the Drake equation, gives us a simple way to calculate the number of civilizations in our galaxy that are sending signals into outer space. The Drake equation relates the number of possibly habitable planets in our galaxy, fraction of habitable planets that actually have life, fraction of life-bearing planets on which a civilization capable of interstellar communication has arisen at some time, and the fraction of life-bearing planets that are communicating now. In short, the Drake equation tells us how many civilizations we could possibly contact right now. Because we do not actually know how many possibly habitable planets there are in our galaxy, we cannot accurately calculate the number of civilizations that are communicating right now. However, the Drake equation is still useful as it relates all of the factors necessary for us to determine the number of communicating civilizations, and we can therefore make a general estimate of the number of civilizations we could possibly contact today.

The Drake Equation

Climate Change: Debunked

Predictions of how global temperature may change due to greenhouse gas emissions

Contrary to popular belief, Earth’s climate has not always been the same; just in the last 650,000 years there has been several cycles of temperature rise and fall due to small changes in Earth’s orbit and the amount of energy Earth receives from the Sun. However, in the past 50 years, Earth’s climate has changed dramatically, and scientists predict this rapid change in climate to be the result of human activity within the past century with greater than 95 percent probability . Satellites orbiting Earth have enabled scientists to collect many different types of information about our planet’s climate on a global scale while allowing scientists to pinpoint the direct cause for this drastic change in Earth’s climate. Many scientists can agree that the main cause of this warming trend is due to the human expansion of the “greenhouse effect”, where Earth’s atmosphere traps heat radiating gases which in turn causes a global temperature rise. Certain gases, such as carbon dioxide, methane and nitrous oxide, trap heat in Earth’s atmosphere. While these gases have always been present in Earth’s atmosphere, the burning of fossil fuels such as coal and oil has dramatically increased the amount of greenhouse gases in our atmosphere, as carbon dioxide levels have risen from 280 parts per million to 400 parts per million over the past 150 years . While the consequence of changing the natural composition of our atmosphere are difficult to predict, certain effects seem likely such as:

. An average increase in Earth’s temperature.

.Warmer conditions resulting in more evaporation and precipitation, causing some regions to be wetter and other to be dryer, therefore resulting more a extreme climate.

.A larger greenhouse effect will warm oceans and melt glaciers, resulting in sea level rise.

.Higher temperatures and shifting climate patterns may change the areas where certain crops grow best.

There are four major factors affecting long-term climate change: changes in axis tilt, changes in reflectivity, solar brightening and changes in greenhouse gas abundance. Small gravitational tugs from the Moon and other planets can cause the tilt of a planet’s axis to change over long periods of time, therefore changing the angle that sunlight hits Earth resulting in global climate change. Due to the fact that the Earth’s axis tilt has not changed in the past 150 years, it is evident that changes in axis tilt is not the cause of our current climate change. Similarly, a change in a planet’s reflectivity, due to factors such as increased cloud cover, has remained relatively constant over the past century therefore does not contribute to our present global warming. Theoretical models of the Sun also tell us that the Sun has gradually brightened with age, therefore increasing the amount of solar energy reaching Earth. Studies have shown that solar variability has played a vital role in past climate changes, such as a decrease in solar activity is thought to have triggered the last Ice Age over 7,000 years ago. However, it is evident that the current climate change cannot be explained by changes in solar energy due to several reasons. Since 1970, the average amount of solar energy received by Earth has remained relatively constant. Similarly, if global warming were caused by increased solar energy, then scientists would expect to see warmer temperatures in all layers of the atmosphere. Instead, they have observed cooling in the upper atmosphere and warming in the lower atmosphere, which is a result of greenhouse gases trapping heat in the lower atmosphere. Finally, climate models that include solar energy are unable to reproduce the observed temperature rise over the past century without including the effect of a rise in greenhouse gases. Therefore, it is evident that the dramatic climate change we are experiencing now is due to increased abundance of greenhouse gases in our atmosphere, and the data points to mankind as the cause.

Anyway, I could probably go on and on about this but… climate change is real! Believe it! There is hope, though. Debunk the myth, tell your neighbors of this pressing issue and and as a global community we can come up with ways to reduce our carbon footprint and save our planet. 🙂

Nuclear Fusion

The Sun generates energy by fusing hydrogen into helium due to a process known as nuclear fusion. Fusion occurs within the Sun because the plasma in the solar core is full of hot gases that collide with one another at extremely high speeds. In most cases, electromagnetic repulsion forces deflect the nuclei of the two atoms preventing collisions, however, if the nuclei collide with sufficient energy, they can fuse together to form a heavier nucleus. A force known as the strong force binds protons and neutrons together in atomic nuclei, is the only natural force that can overcome the electromagnetic repulsion between two positively charged particles. In order for nuclear fusion to occur, the two charged nuclei must be pushed close enough together for the strong force to overpower electromagnetic repulsion.

The Sun

The high temperatures and pressures in the Sun’s core are what allow nuclear fusion to occur. High temperatures provide atoms with more energy which in turn causes atoms to move faster therefore increasing the probability of collisions occurring. The high pressure on the Sun’s core is important for nuclear fusion because without it the solar core would explode into space, therefore halting all nuclear reactions.

The overall reaction of nuclear fusion proceeds through several steps known formally as the proton-proton chain. This chain of reactions begins with two protons fusing to form a deuterium nucleus consisting of one proton and one neutron. The deuterium nucleus then fuses with a proton to produce a helium-3 nucleus made of two protons and one neutron. Finally, two helium-3 nucleus combine to form a helium-4 nucleus consisting of two protons and two neutrons, releasing energy in the process. This energy produced from nuclear fusion provides the energy necessary for live to thrive on Earth. If the Sun were to suddenly halt all nuclear fusion this would be detrimental for all living organisms on Earth. There is a reality to this statement, though: the Sun will eventually run out of fuel to perform nuclear fusion and then it will die. Our Sun is currently halfway through its fuel reserves, so in 7.5 billion years our ancestors will have to come up with another way to provide energy for Earth, or they will have to move to a another solar system. Yikes! Thank goodness this will not happen any time close to my lifetime so I will not have to deal with this problem.

The Universal Law of Gravitation

  Newton’s universal law of gravitation is a fundamental aspect of modern science. The law states that every mass is attracted to every other mass through a force known as gravity. The strength of the gravitational force between any two objects is directly proportional to the product of their masses, which means that increasing the mass of one object increases the gravitational force between both objects. The force of gravity between two objects is also inversely proportional to the the square of the distance between two objects, therefore the force of gravity decreases as the distance between the two masses increases. Newton’s law of gravity extends to Kepler’s laws, as the inverse square law for gravity leads directly to elliptical orbits for planets orbiting the Sun. Newton showed that two objects attracted by gravity both orbit their common center of mass, which is the point representing the average position of mass between the two objects. For example, in a binary star system with both stars of equal mass, the center of mass lies directly between the two objects therefore the stars would orbit around themselves. However, in our Solar System, since the Sun is so much more massive than planets, the center of mass between the Sun and any planet lies inside the Sun, and as a result the planets orbit around the Sun. Prior to Newton, many people saw Kepler’s planetary model for our Solar System as just another theory. By explaining Kepler’s complex laws in terms of basic laws of physics, Newton was able fully legitimize Kepler’s theory and thus convince the world of a heliocentric Solar System.

Objects Orbit Their Common Center of Mass

Galileo Galilei: Historical Astronomers in Context

Galileo Galilei: born Feb. 15 1564 ; died Jan. 8 1642

December 1613: Galileo finds evidence that supports the Copernican system of a heliocentric Solar System, saying that the ocean tides increase and decrease according to the rotation of Earth on its axis and Earth’s revolution around the sun.

April 12, 1633: Galileo is put on trial by the Catholic church where he is forced to recant his belief of heliocentrism. Galileo is then put on house arrest and banned from continuing his research.

  Pope Urban VIII (April 5 1568- July 29) 1644 was responsible for putting Galileo on trial for heresy against the Catholic church. The pope had previously given Galileo permission to write about the Copernican theory, but Galileo’s publication of Dialogue Concerning the Two Chief Systems of the World in 1932 embarrassed the church forcing the pope to bring Galileo to trial.

The life of Galileo often embodies the challenges associated with making new scientific discoveries. Despite all of the overwhelming evidence pointing towards a heliocentric theory, the world was not ready to accept it. Throughout human history, we have always selfishly deemed humans as the center of the universe. At the time of Galileo’s discovery, our egos were not ready to believe that we are not as special as we had previously thought. I believe that this bias has delayed many contributions to modern science, as people try to fit the data to match their preconceived notions about our world, rather than letting the data speak for itself.

Powers of Ten

Our universe is so vast it is simply mind blowing. The true nature of the size of our universe can be understood by examining powers of ten. We begin with a picnic scene one meter wide viewed from one meter away. Every 10 seconds we will look 10 times further away and our view of the picnic will be 10 times wider. Zoom out to 10^2 meters, the distance a man can run in 10 seconds. Back up even further  to 10^3 meters, the distance a race car can travel in 10 seconds. Now at 10^4, the distance a supersonic airplane can travel in 10 seconds. At only 10^6 do you begin to see the entire sphere of the earth. At 10^7, background stars are so far away that they do not yet appear to move. At 10^13 we see our entire solar system, and at 10^14 our solar system shrinks to one bright point in the distance, and our sun is now merely just one star among the million others that scatter our galaxy. At 10^20, we reach the outskirts of our galaxy and begin to see the spiral shape of the Milky Way. At 10^21 we see the clouds of Magellan and other satellite groups, and now one million light years away at 10^22 we begin to see groups of galaxies. Fast-forward to 10^24, the largest view of the universe that has been discovered by man. At this vantage point in space, galaxies start look like dust. There appears to be more emptiness than matter, but this emptiness is normal, “as the richness of our own neighborhood is the exception” (Powers of Ten). Centuries ago, people considered earth to be astronomically unique. We know now that is incorrect, that earth is no different from the  millions of other habitable planets in our universe. Why is it then, that many people still consider human life the most important thing in the universe? At 10^24 meters away from our picnic scene, when galaxies look like specks of dust littered throughout the universe, you begin to realize how insignificant human life is in comparison to the grand scheme of things. However, many people in contemporary society tend to forget this fact, as their inflated ego has led them to believe that humans are the most important thing out of everything in our vast universe. Knowing just truly large our universe is can be quite humbling, and I believe that is an important fact to be mindful of.

The Observable Universe