We all know how infallible Einstein was. Yet, all previous scientific genius has come into question as time passes. At some point, the whole issue of traveling at the speed of light, and Einstein’s assertion that this is the cosmic speed limit, will be seriously challenged, if not rebuffed completely. We might keep in mind three points: 1.) Just a few decades ago, the speed of sound was considered an impossible barrier, 2.) Einstein’s use of the speed of light as a constant, with mass a variable, was a convenience to completing mathematics, not founded on actual study of the velocity of photons, or the rubberiness of the properties of mass, 3.) There are now numerous theories and observations pointing to the likelihood that the speed of light is not a constant, nor is it a limit. 4.) Quantum entanglement appears to suggest that forces do act across great distances simultaneously, which, regardless of tortured Einstein disciples effort to explain it away, suggest that information can travel faster than the speed of light. But let’s put all this aside a moment and assume the speed of light is just really fast, and see if it’s even relevant.
There are a few things we know with fair certainty. One is that the human body cannot sustain high rates of acceleration for long periods of time. Aerobatic pilots can train to sustain upwards of 7G for a few seconds, military pilots very brief encounters slightly above that. With exceptional training effort, sustaining high G forces is a significant issue for humans in attaining the speed of light. Here’s why: The speed of light is 186,000 miles per second. That’s 669,600,000 miles an hour, or 982,080,000 ft./s. If we were to accelerate at a rate of 1G (32 ft/s/s) it would take 1 year to reach the speed of light, 118 days at 3G, and 71 days at 5G – the upper limit of endurance of human physiology for short bursts. So, let’s assume that exceptionally trained pilots and crew could manage to withstand 3G for 118 days, it’s possible they could survive and attain light speed velocity (near light speed for those unable to get past Einstein as infallible).
Now, let’s look at another limitation – fuel consumption. Let’s assume we can build any sort of engine capable of 200 miles per gallon of fuel while accelerating. At 669,600,000 MPH, this equates to 5,704,992,000 gallons per hour, which, at 6 pounds per gallon, would come to 34,229,952,000 pounds per hour. At this velocity and efficiency, the spacecraft would consume all of the remaining known fossil fuel on the planet earth in just 1.36 years, at zero drag, assuming 100% of all remaining oil is used and converted to fuel. Now, assuming we can maintain 200MPG while accelerating at a constant 3G for 71 days, we could maintain the speed of light for just 294 additional days. Since the nearest sun is many light years away, we will have spent an enormous amount of energy and time, to attain…. nothing. Of course we would not use oil in this effort, as that’s obviously a poor choice – unless you are from the days of Jules Verne.
Let’s say we can concoct a fuel capable of moving a ship of any size at a rate of 1,000 miles per gallon, and that fuel weighs just 1 pound per gallon, the consumed fuel weight still adds up to 1,140,998,400 pounds per hour. If we were to equip the ship to achieve the speed of light and maintain it for just 1 year, the amount of fuel required would total 7,006,694,400 gallons/pounds. Let’s say that we can compress these gallons of fuel into a 1/2 cubic feet of space, the volume would still be over 3.5 Billion cubic feet. That’s a huge fuel tank for a ship that needs to accelerate at a constant 3G and maintain 1,000 miles per gallon, even in the vacuum of space.
Perhaps Einstein chose to simply state that the speed of light is not possible in order to save us the effort of finding this out the hard way? With what we know of propulsion and human physiology, the speed of light is unattainable. Perhaps one day we will discover some motive force that delivers efficiency beyond anything imaginable. We’ll still suffer the hard reality that unless we can find a way to survive the acceleration required to attain the speed in a reasonable time, and still function (eat, sleep, et al), it won’t really matter. Unless we can attain and maintain or exceed that speed for many years, if not decades, reaching even the nearest solar system is beyond our reach. For these reasons, the only hope we have of touching the stars, literally, is through means other than the conventional thrust/acceleration force approach.
What this has to do with Solid State Lighting will remain a complete mystery. However, with the size of the fuel tank, and the need for maximum efficiency, certainly there will be no place for inefficient lighting to read by as this craft hurls into the abyss.