Reaching For The Stars
A Look At Time and Space
The notion of time and space was probably put into theoretical perspective by Albert Einstein at the turn of the 20th century. It was an extension or amplification of the principles expounded upon by Sir Isaac Newton, who’s discoveries in physics have become a foundation for everything we do, including space flight.
Einstein, to ultra-simplify things, put forth the concept that there is a maximum speed limit to the universe in terms of Newtonian or three dimensional physics and this upper limit is the speed of light, which is some 186,000 miles per second/per second (a term that implies continual thrust at 186,000 miles per second in the opposite direction – to view this properly think of a gun firing a bullet at 186,000 miles per second, once the bullet leaves the barrel no further “push” is provided, the concept of light speed is like that of a rocket where the engines continue to push the bullet with on-going thrust).
If Einstein is correct, then nothing in our physical universe can travel faster than light.
Einstein also postulated that the faster one travels the smaller one becomes. We, of course, can see physical evidence of this in the Doppler shift of both sound and light as it travels towards us and then passes us. At the front of the sound or light the waves are close and short, at the end they are longer.
Now, why is this all important to space travel?
Well, to put someone on the moon at our current speeds takes a week or more of time, while at the speed of light it would only take a few seconds.
Once upon a time it took a week or more to get from New York to London by boat. Today we can do this in a few hours with jets at great speeds of travel. Boats travel at about 20 miles per hour, while jets travel at about 300 miles per hour.
Space ships travel at about 30,000 miles per hour, but if we could get this up to 500,000 miles per hour then a trip to the moon would take hours, not days.
A trip to Mars would currently take a minimum of 40 days, but only at “optimal times” which come every 15 or so years when our distances are close (33 million miles). At the worst of times our distance is several hundred million miles, which takes the better part of a year to travel. If we could get up to 500,000 miles per hour then we would make that trip in about 3 days at best and a month at worst.
Right now at our current speeds it will take hundreds of years for a probe to reach the nearest start (Proxima, in the constellation Centaur). Even at 500,000 miles per hour it would take years and years and years to accomplish this feat!
At Einstein’s maximum speed limit of light, it takes a tad over 4 years to reach the closest of stars. Now, imagine you taking that trip? Four solid years in a space ship before you can get off and walk somewhere else – and, if there are no planets around Centauri, you have to stay in the ship for another 4 years for the trip back.
Einstein also states time grows slower when you reach those speeds. So your 8 year round trips amounts to a few minutes of aging for you. If two twins existed and one went on that trip, while the other didn’t, the one who stayed on Earth would age 8 years while the one on the trip ages a few days or months.
Einstein also says you grow smaller the faster you travel. Space in your immediate time frame shrinks. This is the time-space paradox. Your mass, your matter grows smaller and more compact. So small that you might be the size of an atom by the time you reach light speeds and then when travelling through space you’d encounter free hydrogen atoms that are as big as you are!
The basic points of the Einstein theories is that there is some upper limit of speeds we can attain in our physical universe, after which we might not be able to survive or return from. We might get the equivalent of the “bends” if we travel too fast in space and then slow down. The bends, are little nitrogen bubbles underwater divers get when they go too deep and surface too fast.
We don’t know at what speed we can actually survive. Certainly 500,000 miles per hour is a realistically attainable speed, which would make trips across our solar system practical, even though it would take a year or more to get to the outer planets. A million miles per hour starts to sound fantastic, but at one point in time it was said travelling at speeds greater than 65 miles per hour would crush a human.
Einstein, in his theories on relativity, states that once you reach a speed and stay there for a bit, your world becomes normal and natural. We experience this daily in an elevator or commercial jet liner. An elevator that starts moving at gradual speeds and then increases to a level speed. Speed is only a modest problem to those traveling in the car until they hit something or have to break real fast. Once a plane takes off from the ground you no longer feel the (Newtonian) gravity or (Newtonian) inertia even though you are up several thousand feet off the groun and travelling cost to 200 miles per hour. Your senses and perception are relative to the world in which you live and how you observe everything else around you. An object dropped from a moving bus falls straight down to the ground from the relative observation point of the person dropping the object. To a person looking at the bus from a street corner that object is moving into two directions (forward with the inertia of the bus and downward) based on their relative point of view. Both observations are correct within their respective worlds. Newtonian physics, however, has to take relativistic concepts into account in some situations in order to be accurate and absolute. Thinking "relativisticly" is like thinking outside of the box. Einstein added "time" to the physical (and Newtonian) dimensions of width, height and length.
Inertia is forward momentum. Sudden breaking is why we need seat belts in cars. Slow and gradual breaking will only throw you off balance a bit. This is why we have seat belts in planes. Once you are used to moving at 300 miles per hour you go through life as normal. When the plane lands and slows down you can feel the change in inertia. When the plane takes off and gains speed you are pushed back into your seat and feel the tug of gravity as the plane climbs upward at 150 miles per hour.
Going even half the speed of light may not be a practical thing in our physical universe, then again once we do it, we might find that there is nothing to it! More than flying in a plane at 300 miles per hour! But, at half the speed of light it would take 9 years to reach the closest of stars and 18 years for a round trip. That’s an awful long time to be cooped up in a space ship!
Are there solutions? Einstein felt so. He and his contemporaries envisioned that time and space are relative commodities and that ruptures which are termed “worm holes” would allow us to travel from the Earth to Centauri in mere seconds. It is felt that it might be possible to travel great distances instantly, without the need for momentum, thrust or speed. Only the ability to somehow traverse the fabric of our spatial universe in some yet unimagined method.
Considering how long it took mankind to fly from the first moment a bird was observed (thousands of years) is just how long it may take man to go from here to there in an instant. It’s simply a matter of learning the rules of the universe and applying tools properly.
That’s all it took for the Wright Brothers to put a heavier than air craft aloft at Kitty Hawk. That’s all it took for us to put a rocket aloft with men on board to land on the moon.
Right now this is the realm of science fiction, with shows like Star Trek that have “warp drives” allowing a ship to travel from here to the edge of the universe in a week or less, something that at our best space flight speeds would takes a million years to accomplish!
Once upon a time in the realm of science fiction man traveled to the moon. Today it is a reality. Tomorrow maybe we can reach for the stars!
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