I'm not the one arguing it. That is my understanding of the scientific explanation. As for the tree - it depends on your definition of sound. Is sound the vibration of the air, or is it the perception of that vibration? Going to your example of the European monarch - if the outpost isn't aware of it, that means the *effects* of the death haven't reached them yet. So they continue to act as if the monarch is alive, until they learn otherwise. A new monarch may have issued a new decree or changes in laws - but until they reach the outpost, as far as they're concerned, those changes haven't happened.
Whether it is there or not makes no objective difference to us. From our frame of reference, it's not there. That's what relativity is all about.
For whatever it's worth, I'm currently a beta reader for the sixth book in a sci-fi series by a friend. Faster-than-light (FTL) travel is a staple in all six books. I've never bothered to think about it -- after all, it's fiction. The universe in which the books are set (which happens to be our universe, as portrayed by the author) has FTL travel, and that's that. Until I stumbled into this discussion, I never even questioned it. In fact, I just received the latest three chapters this morning. FTL travel and time dilation are mentioned, and it still didn't set off any "But that's impossible!" alarms; it just sent me back to this discussion to point out that, if the story is well-crafted and well-told, it doesn't matter if FTL travel is scientifically possible. At one time, people believed the Earth was flat.
That's the point of the thread though. I entirely agree - an explanation is not necessary for enjoyable sci-fi. I'd say the advice in the OP is poor.
Yes, that part I agree with. But I think you're conflating two different things. The event is not the same as the effects of the event, and possibly my understanding is wrong but I don't think relativity suggests that it is.
The link I posted above should provide some explanation. edit: I'm going mad. I'm sure I posted a link.
Here we go: This may or may not help: http://www.physicsmatt.com/blog/2016/8/25/why-ftl-implies-time-travel#:~:text=Because light travels at 45,away from the time axis. I can't say I fully follow the explanation myself.
So if someone is deaf, there is no sound in the world? Not my example, but the fact that the remote colonists don't know about the event and continue to live under the old laws until they learn of the changes in no way means that the death of the monarch and the enactment of the new laws hasn't happened until they receive the news. History records that King George III of England died on 29 January 1820. If the news didn't reach Canada until -- let's say -- March 15, and didn't reach India until April 21, would you argue that he died on March 15, or on April 21? What if the news reached Halifax on March 15, but didn't reach the western territories until August? What if the news reached Bombay on April 21 but didn't reach Calcutta until April 30? When did he die?
If you argue that sound is the perception of the vibration of air, then yes, that's correct - from their perspective. This is the important bit - from the perspective of the colonies, he died when they got the news. Let's say the Governor-General of India had to sign a decree between 29th Jan and 21st April - who would he have signed the decrees in the name of, King George III, or King George IV? It's a little bit like Schroedinger's cat - until you open the box, the cat is both alive and dead.
I'm not arguing either way. Both definitions could be valid at the same time, depending whether you're looking at it from an anthropocentric or scientific point of view.
Cause & Effect in action... List of nearest stars and brown dwarfs - Wikipedia You are a Captain of a star ship orbiting Mars, the ship can travel at c the speed of light. Orders arrive that you need to go to Barnard’s Star system immediately. You order Astrometric Redshirt to plot a course…. So, the Redshirt first finds were Barnard’s Star location. Its about 6 light years from our Sun, not that far at all. However, his observations of the star are dated. He needs to tell the Astrometric computer to project the location of the system in six years’ time. This will give him the current location. Now he needs to ask the computer to project the star systems location in another 6 years’ time. This will give him the target location. The ship will travel for 6years at c and arrive in the right place. This is twelves years different in time as we look at things right now. The computer needs to also back calculate orbits of objects between us at 6 light years out. What may cross our path. You give the order to engage… Because the ship is travelling at c for six years the amount of time elapsed on earth is 6years. The amount of time that’s observed locally on the ship is roughly six hours. The Galley didn’t need to stock up on 12years worth of rations! Upon arriving at Bernard’s Star system our current information will be at least 12years out of date. It’s location and planet orbits are all predictions only not facts. MartinM.
The reason I think most, including me, don't follow the relativity/causality/FLT 'pick two' concept is that we don't fully understand special relativity at an elite level. We are still viewing things in an 'absolute' time which may not exist. This video does a good example covering it, but I must admit I was surprised and didn't fully understand the part at 10:18 about Bob traveling at .87c viewing Earth as having a slow clock (from Bob's perspective). I thought it would be the opposite (that he'd view Earth as having a faster clock), but this is because it's special relativity. Actually, I still don't fully understand it, but given the example he shows and the assumptions I have a little bit better grasp of it: Of course this doesn't mean you can't have a story with FTL travel or communications that ignore these Paradoxes. It's been done thousands of times and hardly anyone's complained.
@Steerpike Your example doesn’t break causality. The confusion is measuring distance in time. Use the same example using B-roads and a motorway. Travelling between Leeds and London will take over 7 hours using B-Roads. However, use the M1 and it will take just over 2 hours. Now re-tell your story... Read my post above about observational time as well. MartinM.
Cause & Effect in action... Part 2 Spoiler Cause & Effect in action... List of nearest stars and brown dwarfs - Wikipedia You are a Captain of a star ship orbiting Mars, the ship can travel at c the speed of light. Orders arrive that you need to go to Barnard’s Star system immediately. You order Astrometric Redshirt to plot a course…. So, the Redshirt first finds were Barnard’s Star location. Its about 6 light years from our Sun, not that far at all. However, his observations of the star are dated. He needs to tell the Astrometric computer to project the location of the system in six years’ time. This will give him the current location. Now he needs to ask the computer to project the star systems location in another 6 years’ time. This will give him the target location. The ship will travel for 6years at c and arrive in the right place. This is twelves years different in time as we look at things right now. The computer needs to also back calculate orbits of objects between us at 6 light years out. What may cross our path. You give the order to engage… Because the ship is travelling at c for six years the amount of time elapsed on earth is 6years. The amount of time that’s observed locally on the ship is roughly six hours. The Galley didn’t need to stock up on 12years worth of rations! Upon arriving at Bernard’s Star system our current information will be at least 12years out of date. It’s location and planet orbits are all predictions only not facts. MartinM. The star ship you captain as spent the last month researching all things to do with the Bernard’s Star system. It is now time to return home. You give the order to the Astrometric Redshirt to plot in a course. The Redshirt’s observation of the Solar System hasn’t moved or changed an inch since we left? He asks the Astrometric Computer to calculate the Solar Systems position forward six years. This is its current position now; he then projects the solar systems place in another six years. This will be our target like we planned on the outward journey. Here the Astrometric Computer hits a snag. Its look back calculations at what may cross our path is done from a new location. It will need to extrapolate existing data and observed data from its Bernard’s Star position. Error rate increases. You give the order to engage... The Ship travels at c for six years, the amount of time elapsed at Bernard’s Star & Earth is six years also. The amount of time that’s observed locally on the ship is roughly six hours. On our arrival in orbit around Mars You complete the final log entry before dismissing the crew. Mission: Completed Research of Bernard’s Star taking a total mission time of 30days 12hours. Taking some shore leave, you go visit your younger sister and her baby and your parents. You know what’s coming, but its still a shock to the system all the same. Your little sister looks visibly older, much older than you. Her baby has turned into a teenaged goth angst monster. Your parents no longer middle aged now look old and grey. You, you however still look exactly the same as when you left. Your month-long mission took over twelve years for those left back on Earth. That’s the effect of time dilation and cannot be ignored in Sci-Fi. For one thing the mission cost would be enormous for a short month’s work. You look at your Citibank account... A current naval Captain earns around $144,000 a year or $12,000 a month. For your month’s work doing Research you’d find your bank balance slightly more than $12,000. Close to $2.5million brings a smile to your face. So, twelve years is 144 months plus the month of actual work equals 145 months or $1,740,000. Add a 3% inflation rate and bingo $2.5million. The Operational cost of running just this quick mission with crew would turn into a long term cashflow drain. The Space Navy is not getting value for money, yet you’d balk at been paid at an Observable ship rate... Do you go on half pay for travel time? In Sci-Fi there is an economic penalty to be paid somewhere. The Marines in Aliens had to be paid even though most of the mission they’re in statis. The expense of running a human based tactical force be so large a cost, it would restrict its size and freedom of movement. This means we would be more reliant on automated or AI led missions, leaving human forces close to Sol. This is something that’s very hard to deliver in Sci-Fi. Star Trek has no currency of sorts, so something must need to happen in order to build a starship out of titanium? Star Wars, the crippling cost of enforcing and maintaining the Empires rule of authority across a Galaxy. No wonder it collapsed completely in under 30 years... The Sailors them selves would be facing a lonely career. All close family and friends would have passed away naturally before your tour of duty ends. What type of life is that? Do you allow partners to serve on ship or spouses as guests? These are real problems that are not far away. Joe Haldeman’s The Forever War shows these issues. Apologies for the ramble, but did have fun with it. MartinM.
Resurrecting the causality conversation on account of seeing that Nobel prize for physics is going to researchers of quantum entanglement. Can anyone explain why entanglement isn't a violation of causality? Is it because, so far as we know, you can't transmit information?
I can't really, but I do know that as a general matter no one's ever been able to reconcile general relativity (which is where the causality discussion comes from) with quantum mechanics. To do that would be the "Grand Unified Theory" or "Theory of Everything" that you sometimes hear physicists talk about. There have been some contenders over the years, like string theory IIRC, but it's still one of the biggest unsolved problems in physics.
From a science fiction perspective, I guess the question is how much room to invent does an author have while still remaining within the purview of SF. We know there is a black box between general relativity and quantum mechanics. If you used quantum physics to support a method of instantaneous communication in an SF novel, is that still sufficiently rigorous to claim it as SF (or hard SF) even though it violates relativity?
@Steerpike OK will try, and please anybody correct me if wrong. It is not possible to use entangled particles to send messages faster than the speed of light. The basic common example looks like this, Alice and Bob share a pair of particles that can be measured in one of two quantum states, which we’ll call ‘0’ and ‘1’. These particles prepared in the LHC are entangled in which a measurement of the state of Alice’s particle is correlated with the state of Bob’s particle. That is, if Alice measures her particle in a state ‘1’ at precisely noon midday then she knows with absolute certainty that Bob’s particle will also be in a state of ‘1’ also. This doesn’t matter as to where Bob’s location is, in New York or the Moon or Yarvin 4. Wow already you can envisage a brilliant system of communication much faster than FTL. However, there’s a problem: entanglement only works if you ask a particle, “What state are you in?”. If you force an entangled particle into a particular state, you break the entanglement. Its observation only. MartinM.
So how would I write a story of going to another planet using a ship that I suppose (in theory) could be possible to build in 5,000-100,000 years?
Or you could do it like Futurama and say that actually the ship is moving the entire universe around it.
