Will humans ever develop faster than light travel? by Richard Muller
Answer by Richard Muller:
I hope not.
My reasoning is strange but compelling: if humans can travel faster than light, it will demonstrate that free will does not exist. That discovery would sadden me.
The logic is described in detail in my recently published. I explain it in a new paradox I invented called “the tachyon murder”. (This is a paradox that I invented when teaching relativity theory at UC Berkeley.) Here is the section from my book in which I describe the tachyon murder:
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The strange relativity result that the order of events can flip for different reference frames leads us into a new aspect of reality: the deep issues of causality and free will. These issues can be dramatized by the story of the tachyon murder.
A tachyon is a hypothetical particle that travels faster than the speed of light. Remarkably, relativity does not prohibit particles from traveling that fast. It says only that massless particles must travel at lightspeed, and that particles that have a real rest mass cannot travel at that speed (since the gamma factor would be infinite, and they would have infinite energy). The equations don’t prohibit faster-than-light travel per se….
Yet despite the upside of [discovering a tachyon], I decided many years ago not to bother searching for a tachyon. My reason borders on the religious. I believe that I have free will, and the existence of tachyons would violate that belief. Let me explain.
Imagine that Mary is standing 40 feet away from John. She has a tachyon gun that fires tachyon bullets that move at 4c, four times the speed of light. She fires. Light moves at a speed of 1 foot per nanosecond (billionth of a second), so her tachyons move at 4 feet per nanosecond. In just 10 nanoseconds, the tachyon bullet enters John’s heart and kills him. Let’s assume he dies instantly.
Mary is brought to trial. She doesn’t deny any of the facts I just described, but she insists on an unusual change of venue. She says she has a right to argue the case in whatever reference frame she chooses. They are all valid, the judge knows, so he allows her to proceed. She chooses a frame moving at half lightspeed, ½ c. Since that frame is moving slower than the speed of light, according to relativity it is a valid reference frame.
In the Earth frame, the two events (fire gun, hit heart) are separated by +10 nanoseconds. As I show in Appendix 1, the same two events described in a reference frame moving at ½ c have a time separation of –15.5 nanoseconds. The negative sign means that the two events occur in the opposite order. The bullet enters the victim’s heart before Mary fires the gun! Mary has the perfect alibi. John was already dead when she pulled the trigger. You can’t murder a dead person. She expects to beat the rap.
The tachyon murder example is based on the same relativity principle that caused confusion in the twin and pole-in-the-barn paradoxes. If two events are sufficiently separated in space, and not too different in time, then there will be frames in which the order of events will reverse. Such distant events are called “space-like.” Two events that occur near each other but separated in time are called “time-like.” The order of space-like events depends on the frame of reference; the order of time-like events does not.
… I refer you to Appendix 1 [of my new book] for the explicit calculation. Is the tachyon murder scenario possible? How could analysis in the ½ c frame be valid, if it has such an absurd implication? Does this mean that tachyons don’t exist, or does it mean that relativity is nonsense? What if tachyons are really found? …
One possible resolution for the tachyon murder paradox is that, in this world that has tachyon guns, Mary does not have free will. Even though she pulled the trigger after John died, she had no choice but to do so, since without free will, choice is illusory. All of her actions arise from influences and forces outside of herself. John died because it was inevitable that Mary would pull the trigger; the inevitability of physics created the combined scenario of shooting and death, and the order in which they occurred is irrelevant. There is no paradox if the world is governed by causal physics equations. The scenario presents a problem only if you think people have free will, if you believe that Mary could have decided not to fire the gun. If physics rules, then she does only what the various forces and influences on her cause her to do.
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So if any normal object, such as you, can travel faster than the speed of light, it means that free will does not exist. I consider it remarkable to realize that free will has actual consequences for physics, and that we can describe a discovery that would falsify it. I don’t think this astonishing fact has been published prior to my
On Friday September 23, 2016, at 2 pm Eastern time and 11 am Pacific, I am hosting a Quora session in which I will try to answer as many questions as I can. The topic is time, its flow, the meaning of the mysterious and ephemeral moment we call now, my, cosmology, and anything else of interest. I think you can get to the Quora page for this session by