Wyoming Stargazing
Hey Everybody, Samuel Singer here, the Founder and Executive Director of Wyoming Stargazing, thanks for joining me and welcome to Mind Bending Astronomy. In every episode we’ll share with you..well…a mind bending fact about astronomy.
Last time we explored the effects of time dilation and the twin paradox. We learned that time does not flow at the same rate everywhere in the Universe. In strong gravitational fields like near a black hole the passage of time is very slow compared to the passage of time in a weak gravitational field like around Earth. We also discussed how traveling close to the speed of light through space also results in time slowing down precipitously relative to a stationary observer on Earth. Today, we’ll take a look at whether it’s even possible to travel close to the speed of light.
If you try to accelerate an object with mass to the speed of light you run into a HUGE problem! Remember when we talked about mass being the resistance to motion of an object and the object’s total energy? Well, as the object is accelerated is resists motion more and more and it’s total energy also increases. Thus, more and more energy is needed to continue to accelerate that object. As an object’s velocity approaches the speed of light, its total energy approaches infinity as does the amount of energy needed to continue to accelerate it. Since there is only a finite amount of energy in the Universe, it is impossible to accelerate an object with mass to the speed of light.
I know what you’re thinking. Doesn’t the velocity of the object just keep get bigger and bigger as the object accelerates closer and closer to the speed of light? At low velocities that understanding works just fine. Everything you learned in physics class in high school and college about kinetic energy increasing with velocity is correct at non-relativistic speeds. But remember, the real Universe doesn’t actually work that way. For everyone in the Universe to agree on a quantity of measured velocity you have to use the Lorentz Transformations, which take into account different frames of reference. In other words, everything has to be compared against the Cosmic speed limit, the speed of causality. When you do that, it becomes absolutely clear that objects with mass really do approach infinite energy as they approach the speed of light.
In summary, energy is just as relative as time and space. It’s impossible to accelerate something with mass to the speed of light because of the cosmic speed limit of causality. To learn more about this check out the following videos: https://youtu.be/LTJauaefTZM, https://youtu.be/A2JCoIGyGxc, and https://youtu.be/c4z6RZXv5p8.
Next week we’re going to learn about alternative ways to travel vast distances through the Universe without accelerating to the speed of light. Until then, be well, and don’t forget to look up.
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