Space Exploration: We Need To Travel Near The Speed of Light For It To Be Practical
If we are going to explore anything beyond our solar system and out into the vastness of the universe in a spaceship or probe; we need to seriously increase the speed of our space flight to do it. There is a tremendous difference in distant we travel locally here on earth when compared to the distant we must travel just to get from here to our nearest star, the sun, and beyond. We must come close to the speed of light, which is 186,000 miles per second to transverse the vastness of space if we want to get to the nearest star with an earth-like planet orbiting it. To get a better understanding of speed I will start with speeds we are familiar with and work my way up to the speed limit of our universe, the speed of light.
Speed As We Understand it on Earth
Speed on earth is pretty slow to transverse the vast distant of space. For starters, the fastest sprinter maximum speed is just under 28 miles per hour. A racehorse maximum speed on the track is about 50 miles per hour. To go ever faster we need something with power such as a stock car, which reaches a maximum speed of about 240 miles per hour and with more power such as fighter jet we begin to approach speeds of 1000 miles per hour. The International Space Station orbiting the earth is moving at an astounding speed of 17,000 miles per hour and the New Horizons probe just sped by Pluto at a speed of 52,000 mph. This is the fastest speed a man-made object have traveled and even at this speed it took the probe about 9 years to get there. Even at 52,000 miles per hour this speed is still not enough to do serious space exploration in a spaceship or probe.
NASA recently announced that the Voyager 1 space probe launched in 1977 to explore the outer planets in our solar system finally left the solar system after traveling for nearly 37 years. It finally left the region of particles from the Sun known as the heliosheath, a distant of about 11 billion miles from earth, at a speed of about 38,000 mph and is currently entering interstellar space. At this point and speed it would take Voyager another 40,000 years to reach the nearest star to us.
Now let us look at speed from a different and familiar perspective, in terms of distance. If we had a fast car such as a Lamborghini and travels about 3,000 miles across the United States from New York City to Los Angeles at a constant speed of 100 miles per hour it would take us approximately 30 hours to complete that trip. If we travel to the moon at that speed it would take us about 14 weeks to get there. The moon’s center is about 238,000 miles (average distance) from the earth’s center. And to travel to the last planet in the our solar system, Neptune, at 100 miles per hours it would take an incredible 3,100 years to get there. Obviously, 100 miles per hour is nothing to the vast distance of space. We need something much faster like the speed of light.
Nothing in the universe is faster than the speed of light even though a recent experiment was conducted that indicated neutrinos might travel faster than light. However, further investigations of the results of the experiment indicated the speed of the neutrinos particles was less than the speed of light. After all they were talking about measurements in nanoseconds. For clarity, a nanosecond is one-billionth of a second or a second divided into one billion equal size slices. That is an extremely short period of time.
Light Speed, the Universe Speed Limit
As I mentioned before, the speed of light in miles per hour in a vacuum is an incredible 670 million miles per hour or 186,000 miles per second. At that speed light will travel a distance of about 6 trillion miles in one year or a distant equal to one light-year, a term used by astronomers to define the vast distant light travels in the cosmos. To put this in a different perspective, a beam of light can travel back and forth between New York City and Los Angeles 75 times in a second. It can circle the earth seven times a second. When we look up at the sun the light and heat that we are seeing and feeling left the sun eight minutes ago. Another way of looking at this is if the sun for some reason was to disappear on us we will not notice it until eight minutes later because it take light and heat (infrared light) eight minutes to traverse the 93 to 96 million miles distant from the sun to the earth. In other words, the sun is eight light-minutes from the earth in astronomical terms.
A Serious Need For Speed
Now, if we start looking at the stars and galaxies in the night sky the distant from earth to the stars and galaxies increases dramatically. Everything that we see happening in the night sky already happened millions or even billions of years ago because that is how long it took light even at its speed to travel through the vastness of space to get here. Just to leave our own solar system will take a large and massive spaceship with a lot of fuel to reach the speed of light. Going from zero to the speed of light is not an instantaneous feat. A lot of energy is required to do that. If the spaceship left Earth it will take some time to accelerate to the speed of light. The spaceship would take 1 year to reach Pluto while accelerating to the speed of light and even after passing Pluto it would only be moving at half the speed of light. On the other hand, starting at the speed of light from Earth the spaceship will pass Pluto in a little less than 7 hours. Light from the nearest star, Proxima Centauri, would take a little more than 4 years to reach earth and light from the nearest star, Epsilon Eridini, with a planet similar to earth would take at least 10 years to get here.
Going off the subject a little, the previous statement pretty much explains why earth probably have not been visited by any visitors even from our very own galaxy and they must also have the capability (intelligence) to do so even if there is life out there. Once we go beyond our galaxy the probability of this ever happening seems highly unlikely because the next galaxy is two and half million light years away if they can travel at 99 percent the speed of light. Any speed less than light speed would make it virtually impossible for some form of life to tranverse intergalactic space.
Getting back on track, to get to the edge of our galaxy, the Milky Way, would take us approximately 24,000 years traveling at the speed of light. Any speed less than that will take us almost practically forever just to leave the Milky way to reach intergalactic space; the space between the galaxies out there. And to get to the nearest spiral galaxy, the Andromeda Galaxy, will take us an incredible two and a half million years to get there from earth as previously mentioned. Currently, the twin Voyager probes launched more than 30 years ago are just reaching the point where they will be in interstellar space after passing the wall where the particles from the Sun are stop by the particles originating from interstellar space. This point in space is the edge of our solar system. These probes are traveling at a speed of about 58,000 miles per hour but nowhere near the speed of light.
To Get More Speed We Need More Power
Obviously, to get more speed we need more power. The astronauts would not have made it to the moon without the tremendous amount of power needed to send their rocket there. The space shuttle needs 3 million pounds of rocket fuel to send it into orbit every time it is launched. The weight of that fuel is 20 times the weight of the shuttle. Just imagine how much fuel we need to go beyond the moon. Researchers are currently coming up with alternative means of propulsion for space exploration. There are right now two promising methods; one involves using the particles injected from the sun, which will propel space vehicle equipped with large sails on them. The momentum from these high-speed particles will be transferred to the sails thus giving the spacecraft the boost needed to move through the solar system at much higher speeds. The other method involves using powerful magnets to re-direct ejected high-speed streams of hot plasma gases out of the nozzles of rockets called magnetoplasma rockets to propel the spacecraft at speeds greater than 50,000 miles per hour. Even at this speed space exploration would be limited to just our solar system.
Strange Things Happen To Us At the Speed of Light
If we ever develop the technology to send humans on a spacecraft near the speed of light to explore space they would experience strange events. They would also encounter a very serious and potentially deadly problem traveling at such a high speed.
If a spaceship is moving near the speed of light and impact something out there it would be a catastrophic event. The impact would create an explosion similar to an atomic bomb explosion because the mass of the object would be so great at that speed that it would release an incredible amount of energy (remember the equation E=mc squared) after the collision with another object. Traveling at the speed of light would only be possible in intergalactic space after the spaceship cleared the space within the galaxy.
Strange things happen when it come to speed near the speed of light. The laws of physics behave differently at light speed versus the relatively slow speed we experience on earth. For example, if two cars were each traveling at 50 miles per hours as they approach each other from opposite directions they will pass each other at 100 miles per hours. This is why head on collisions are generally deadly. In the second example, if two cars are traveling in the same direction, one at 40 miles per hours and the other at 50 miles per hours, the faster car will go by the slower car at a relative speed of only 10 miles per hours. Guys you see this effect all the time on the highway you do not pass the other car that fast unless it is not moving.
Now, if you do these same experiments at the speed of light the out come is completely different. In the first example if the two cars each were traveling toward each other at the speed of light from opposite directions they will pass each other at the speed of light, 186,000 miles per second, not double the speed of light. In the second example, the faster car will pass the slower car which is going a little slower than the speed of light, will pass it at the speed of light. This phenomenon happens because the speed of light does not change in the vacuum of space it is always moving along at a constant speed of 186,000 miles per hour so time slows down to keep the cars from passing each at speeds greater than the speed of light. The other effect humans will experience is the time dilation effect of moving at the speed of light. If an astronaut left earth for a 20-year trip into space and back at 99.9% the speed of light he would be surprise to see that 1,000 years have gone by on earth since he left and he will be basically the same in appearance when he left. Our astronauts today experience this time dilation effect when they are in orbit around earth on the space shuttle or space station. When they return to earth they are a fraction of a second younger than everyone on earth because they are moving at 17,000 miles per hours for a few days. I am sure no one noticed that when they return.
As you can see, there are benefits of traveling at the speed of light you will stay young longer, but to achieve this speed will be an incredible achievement in itself if we ever develop the technology to do it. It look like it is going to be a while before we can leave the boundary of our solar system to do some serious space explorations physically.
References: Wikipedia, National Geographic Channel
© 2010 Melvin Porter
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