Space Aliens Shown
As Big Al proclaimed, all objects in the universe, both massive and massless, move through spacetime at the same fixed speed — lightspeed. This is a consequence of 4-dimensional spacetime and the generalization of speed to include a temporal speed component (in addition to the 3-space or spatial speed component).
A photon, that massless quantum of electromagnetic (EM) radiation, is an object whose totality of lightspeed is within its spatial component. Hence, it must have a zero temporal component. Photons never age. A massive object, however, is forbidden by relativity to attain spatial lightspeed, which is the same as requiring that a fraction (greater than zero) of its lightspeed be diverted to its temporal component. Massive objects like protons, humans, and extraterrestrials (ET) age.
Suppose an ET civilization wants to visit another ET civilization (from their point of view), like the one on Earth, such as it is. There is insufficient energy available anywhere to launch expeditions in all directions such that contact can be assured with any reasonable expectation of success, at any non-trivial distance, say more than a light-year. At a minimum, some evidence must first be obtained that an expedition in any specific direction has non-trivial expectation of finding a civilization at journey's end. I posit that receipt of at least one signal of EM communication (radio waves) would be a reasonable pre-condition for the launch of a (massive) expedition. If you are not inclined to grant the reasonableness of such a conjecture, read no further.
A hundred years ago, Earth began EM (radio) broadcasting. Suppose that at least one of those initial broadcasts was sensed by the adventurous ET civilization. They immediately launched their flying saucer toward Earth at their maximum "warp" speed. How far was their journey and what was their speed if they show up this year? If we posit a minimum distance, we can compute their required speed.
There are 50 stellar systems within 16 light-years from Earth. Lets assume our ET civilization lies about 15 light-years from Earth. In that case they received our first broadcast 85 years ago and they would have to have been speeding towards us at a whopping
15 light-years ÷ 85 years = 0.18 lightspeed = 118 million miles/hour
to arrive this year. It is doubtful that even a highly advanced civilization can muster enough discretionary energy to accelerate the total mass of their spaceship and all of its contents to 18% of lightspeed (recall that mass approaches infinity as its spatial speed approaches lightspeed). Let's suppose, however, that the ET civilization is maximally green (they recycle all their beer cans, etc.) such that they are capable of accelerating themselves to 1% of lightspeed (6.71 million mph). How long before they get here?
15 light-years ÷ 0.01 lightspeed - 85 years = 1425 years (from now)
Not to put too fine a point on it, fuggedaboutit.
As Big Al proclaimed, all objects in the universe, both massive and massless, move through spacetime at the same fixed speed — lightspeed. This is a consequence of 4-dimensional spacetime and the generalization of speed to include a temporal speed component (in addition to the 3-space or spatial speed component).
A photon, that massless quantum of electromagnetic (EM) radiation, is an object whose totality of lightspeed is within its spatial component. Hence, it must have a zero temporal component. Photons never age. A massive object, however, is forbidden by relativity to attain spatial lightspeed, which is the same as requiring that a fraction (greater than zero) of its lightspeed be diverted to its temporal component. Massive objects like protons, humans, and extraterrestrials (ET) age.
Suppose an ET civilization wants to visit another ET civilization (from their point of view), like the one on Earth, such as it is. There is insufficient energy available anywhere to launch expeditions in all directions such that contact can be assured with any reasonable expectation of success, at any non-trivial distance, say more than a light-year. At a minimum, some evidence must first be obtained that an expedition in any specific direction has non-trivial expectation of finding a civilization at journey's end. I posit that receipt of at least one signal of EM communication (radio waves) would be a reasonable pre-condition for the launch of a (massive) expedition. If you are not inclined to grant the reasonableness of such a conjecture, read no further.
A hundred years ago, Earth began EM (radio) broadcasting. Suppose that at least one of those initial broadcasts was sensed by the adventurous ET civilization. They immediately launched their flying saucer toward Earth at their maximum "warp" speed. How far was their journey and what was their speed if they show up this year? If we posit a minimum distance, we can compute their required speed.
There are 50 stellar systems within 16 light-years from Earth. Lets assume our ET civilization lies about 15 light-years from Earth. In that case they received our first broadcast 85 years ago and they would have to have been speeding towards us at a whopping
15 light-years ÷ 85 years = 0.18 lightspeed = 118 million miles/hour
to arrive this year. It is doubtful that even a highly advanced civilization can muster enough discretionary energy to accelerate the total mass of their spaceship and all of its contents to 18% of lightspeed (recall that mass approaches infinity as its spatial speed approaches lightspeed). Let's suppose, however, that the ET civilization is maximally green (they recycle all their beer cans, etc.) such that they are capable of accelerating themselves to 1% of lightspeed (6.71 million mph). How long before they get here?
15 light-years ÷ 0.01 lightspeed - 85 years = 1425 years (from now)
Not to put too fine a point on it, fuggedaboutit.
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