# Everything Joe says will become true. Can anybody notice?

Joe has a slightly embarrassing issue.

Simply put: Everything he says is true from that moment on until Joe himself contradicts it.

For example: If Joe were to say that hundreds of people turned up at his birthday party the very fabric of reality would be altered such that, for whatever reason, hundreds of people turned up at Joe's birthday party. This includes editing the past, altering the weather, and manipulating otherwise random events all the way back to the big bang.

Joe can't affect the fundamental truthiness of his statements, and blatant logical or linguistic paradoxes like 'This sentence is a lie' will either do nothing or randomly flip to one of the potential outcomes.

If Joe says something that is physically and universally impossible (for example: 'Pi is exactly equal to 3.14') then nothing happens, but if there is the slightest chance (however improbable) that it may occur then Joe can make it so it did.

Joe is allowed to make temporally paradoxical statements, with the caveat that the universe will preserve his own existence and ability to make statements at all costs. Statements like 'My biological father died before I was conceived' will somehow work themselves out such that they are then true (potentially a sperm donor, or alien clones).

Statements like 'I'm a unicorn' will result in Joe being a sentient unicorn capable of talking, all the way down to potentially rewriting the entire evolutionary history of Joe. Intent means a lot when he makes statements, and in many cases the things he says are subconsciously caveated with 'but other things stay pretty much the same'.

Joe has grown up with this power. To him it is entirely natural. Needless to say he is not the most balanced of individuals and will happily blot entire worlds out of existence without thinking anything of it.

The question is whether it is possible for anybody to notice what Joe is doing, given that the entirety of history will (and in some cases must) be rewritten for Joe's statements to become true.

Taking the unicorn statement as an example, is there any way for people to realise that Joe has rewritten the universe such that he is a unicorn, rather than them just accepting that Joe is a unicorn (or possibly being weirded out by the unicorn that's saying it's called Joe)?

Edit for clarity: Can't believe I forgot to mention this: Joe's memory is inviolate. It's one of the things maintained, along with Joe's ability to make world changing statements.

Edit II: Joe is, in this case, being used as a proxy for various potentially world changing entities in this world.

Edit III: yes, other peoples memories are edited as a natural consequence of the world being different. If they weren't this would be a very simple question to answer. :D

• This is very similar to the Lathe of Heaven by Ursula Le Guin - a guy re-writes the world with his dreams and his psychiatrist manipulates him into dreaming certain things. No one else notices the changes. – Esco Jan 24 '17 at 3:57
• @SPavel The Lathe of Heaven – gerrit Jan 24 '17 at 20:40
• This question is actually about Joe. – Joe Jan 24 '17 at 21:30
• But if, in the future, Joe got a little reckless and denied his own ability, then he wouldn't be in this situation in the first place, and so we wouldn't have this situation. Only a musing. – Drew Christensen Jan 24 '17 at 23:55
• Does Joe want to be noticed in this way, or does he want to remain hidden forever, or does he not really care? I think if Joe has a strong preference either way, then that's what happens. Other entities can only affect the outcome if Joe is too apathetic to ever state a preference. – aroth Jan 25 '17 at 12:13

Yes. Very easily, depending on what Joe wants to change.

1) the universe takes the path of least resistance to validate his statements. Therefore, rewriting the past is only done when no other solution is present. Occam's Razor almost.

2) Joe has not explicitly stated that no one will notice this ability. Otherwise this post would be a moot point.

If Joe decides to predict/alter the future, it doesn't affect people's memory, and can become suspect. Imagine if Joe is growing up and gets excited for Christmas, as many young children do. Imagine Joe says "Santa is coming! Santa will come down the chimney tonight and bring me presents!" Then imagine how the parents may react when a fat, red-suited, jolly man actually does come down the chimney at night and leaves presents.

It shouldn't be hard for him to simply say something that is unlikely and have it happen. He could predict the next election 10 years in advanced, predict any sports game upset, or predict the winning lottery numbers for a week in a row just by saying so. If any of my friends did that, I would notice pretty fast.

So long as he doesn't limit himself to just altering the past, people will notice. He may make them forget, but someone at some point will notice this gift, at least for some time.

• Comments are not for extended discussion; this conversation has been moved to chat. – HDE 226868 Jan 28 '17 at 16:08
• @HDE226868 how do you move conversations to chat? I wanted to do that, but didn't know how or where to ask. – ChronoD Jan 28 '17 at 17:03
• Mods are automatically notified when question discussions get too long. Normal users generally cannot do so, although a small notification may automatically pop up if there has been a continued back-and-forth with another user, allowing you to create a chat room to continue. – HDE 226868 Feb 1 '17 at 1:30

I would say it is highly unlikely for people to discover his ability. If he states that he is a unicorn, he doesn't just turn into a unicorn. Based on your description, it would go back in time, and rewrite history so that he is born a unicorn and now is a present day adult unicorn. So anyone that would know him from the past would know him as a talking unicorn.

The only way really for someone to know he is with such power, is to observe him saying something and then it happens in front of them. But even still, it seems like his power has the ability to erase from existence. So if he says that tree right there will disappear, it will vanish and it's existence will have been deleted to the point that there is no record memory of it. The person observing this would turn to him and say there is no tree there what are you talking about?

You have pretty much given this guy the power to alter everything. Everything he changes would in turn alter everyone's memories unless I am slightly miss understanding something and people retain their memories of what use to be vs what is now. Then yes, it could be very easy to observe him walking around changing things as he pleases. Everything around him would be constantly modified as he interacts and would be very noticeable to the observer.

So kind of depends on how much power his statements have and where you want to go with it.

• Agreed - it does seem like his power re-writes history in a way that makes it seem that things were immediately just always that way. – Matt Bowyer Jan 23 '17 at 22:30
• If he says that tree will disappear, then it will disappear. The observer may conclude that Joe caused it, or he may conclude that an amazing thing happened and Joe amazingly predicted it. The history of the tree will only be changed if Joe says, "There is no true there" with the intent that there never has been. – WGroleau Jan 24 '17 at 8:30
• Or it would change the history of the word unicorn to mean "a guy like Joe." Either way, no one notices. – SRM Jan 24 '17 at 15:11
• My point is that "the tree will disappear" implies that observers will see it happen. "there is no tree there" would be more appropriate for what the answer describes. – WGroleau Jan 24 '17 at 16:04
• If Joe says it will disappear, it will disappear, not never have existed. If Joe says it isn't there, that's a different thing. Disappear is "now you see it, now you don't." – WGroleau Jan 24 '17 at 22:19

It depends what Joe wants.

It is entirely possible that people might notice that something is going on - although depending on the exact mechanism it might be very hard to notice; but if Joe doesn't want anyone to notice then of course he can instantly make that true and it immediately goes away.

• Your answer is basically what I was going to say. If Joe wants/says Suzy will notice the changes I make then Suzy has that ability and she will notice. If Joe wants/says no one will notice the changes I make then no one will notice the changes. – Erik Jan 24 '17 at 1:37
• I think that for the sake of some worth of the question we have to assume that Joe doesn't care if people notice. – TGar Jan 24 '17 at 15:53
• @TGar: then it falls to happenstance. Joe can get caught or not get caught at the author's whim, according to whether or not he happens to use his power for things that someone finds less plausible than that he's a wizard. So if he wins the lottery once, I wouldn't rumble him because it's common for someone to win the lottery. If he wins it 10 times in a row, I can more easily believe that he's somehow fixing the lottery, than that he has a general power of omnipotence. And so on until I run out of "better" explanations and decide he must be rewriting reality. – Steve Jessop Jan 24 '17 at 22:09

Joe isn't changing anything, although he thinks he is. What's actually happening is that he is somehow able to move freely between every alternative world in which a Joe exists. The Everett-Wheeler multiple worlds hypothesis is true with a vengeance, and there is an infinity of worlds larger than even God can imagine (literally: Joe says "God does not exist", and is in a world where God doesn't exist).

This explains why he cannot create the mathematically impossible or the physically paradoxical. Worlds such as these have a mathematical probability of zero, so they do not exist and Joe cannot move into one of them.

Presumably there is some sort of Hilbert-hotel permutation of alternative Joes, which is why he never finds himself face to face with himself, and we never notice any paradoxes. (Alternatively, Cantor dust; the infinity of Joe-containing worlds is a smaller infinity than the totality of worlds).

Any mathematicians reading this are advised not to think about it too deeply, because contemplating infinities stacked upon infinities is well-known to be deleterious to one's health. Joe is blissfully ignorant of mathematics beyond his times tables. We might speculate on what his fate might be, if ever "infinity" came to mean more to him than "a very big number".

• Schroedingers Roulette writ large. Like it. – Joe Bloggs Jan 24 '17 at 20:50
• Joe says "God does not exist", and is in a world where God doesn't exist In other words, nothing happens. =P – Steve-O Jan 26 '17 at 18:40

His power only means that his statements are true, not that people won't be suspicious. If he says something along the lines of "From tommorow on I will be a unicorn and everything else will stay the same" people will remember him being a normal human, when the unicorn starts talking. For the universe it's enough to send a crazy bio-engineer along and transform him into a unicorn over night. No need to change anything else like the memories of his friends or evolution, so why should reality do it?

Just let the universe take the line of least resistance.

• quoted by OP in the comments "yes, other peoples memories are edited as a natural consequence of the world being different. If they weren't this would be a very simple question to answer." so essentially, the memories are changed and altered as a consequence/result of the changes he makes. So if he were to state what you have, From tomorrow on, people would always know him as a talking unicorn and not one day human one day unicorn. – ggiaquin16 Jan 23 '17 at 23:44
• @ggiaquin The premise for his statement was that reality would be twisted by changing the fact "Joe was born as a human" to the fact "Joe was born as a unicorn". I have a different view on this. In my example reality twists by making him transform in the night, so that "Joe is a human tommorow" becomes "Joe is a unicorn tommorow". Reality does not need to revert history in this case (okay, maybe the crazy bio-engineer, but meh ;) ) and therefore the memories of friends do not need to be changed. At least that is how I interpreted OPs question and comments – Sec SE - clear Monica's name Jan 23 '17 at 23:54
• ok I am sold from your point of view as it being a plausible option. I personally don't believe that is what OP intended to have happen but I find that at least as you describe it and what we know of the topic, it is possible :) – ggiaquin16 Jan 23 '17 at 23:58

# The universe is smoke and mist to Joe

I don't think Joe is going to stand out too much all of the time while at others it will seem obvious but it's all irrelevant to Joe.

Fluid universe around Joe

The entire universe can casually rearrange itself entirely around him. One day a careless statement leaves him in a sci-fi universe with hyper-advanced AI who have spotted that everything he's ever said appears to be 100% true.

In the next moment after a casual utterance ,perhaps about dinner tonight, that reality is unmade entirely and the entire history of the universe has placed Joe in a medieval village.

Joe will be protected no matter what, any attempt by a nutjob to kill him or an AI overlord to hotwire his brain will fail because reality itself warps to protect him.

Unicorn Joe won't seem weird because Joe will always have been a Unicorn or there will be a clear path of events that led to Joe getting a unicorn body.

Exceptions

Joe utters the words "your memory and existence will be inviolate like my own" to someone. Perhaps a romantic interest, perhaps someone he simply grabbed onto in the forever shifting churn around him.

Suddenly there is someone who can remember that yesterday Joe was not a unicorn. Suddenly there is someone who can see the weird stuff happening.

Joe can revoke that if he really wants to but perhaps he doesn't.

If Joe is a human... then Joe is going to be a very weird person.

If Joe is a human then Joe was once a toddler going through the terrible 2's.

Imagine the world view of a child who takes it for granted that anything they say out loud is true. Nobody can ever have made this toddler go to bed if they didn't want to. Nobody could ever have made them do anything because they could just scream "I'm NOT going to bed!"

This is an entity which had every wish granted from the moment it could speak and never had to fear anything. The suffering of people around it are as irrelevant to it as shapes in the mist. The people around it shifting as ephemerally as that mist.

• then Joe is going to be a very weird person and then some. Joe would be a very difficult character to write believably. Given his relationship with reality from day 1, Joe would never have to deal with consequences or having to put effort into anything beyond speaking. With no reason to mature it's hard to imagine Joe would ever mentally progress beyond childhood. – Myles Jan 24 '17 at 18:57
• That's what I thought when I saw "It's a GOOD Life" on the Twilight Zone. There's no way that Billy Mumy's character would grow up to be a well-adjusted adult. – Shawn V. Wilson Jan 25 '17 at 17:08
• There was a chance because Bill Mumy didn't have very good control. – Joshua Jan 25 '17 at 23:35

Assuming Joe doesn't actively negate the possibility "No one has discovered my power", then people will begin to notice that at the very least Joe's memory is unnaturally accurate. This could get even more interesting with sequences like:

Person: I like that the moon is a nice shade of yellow.
Joe: The moon is green!
Person: Uh, I know.  Why are you telling me the obvious again?


The person's memory would have been rewritten to know the obvious thing that Joe had just changed, but you'd assume they would still have heard Joe's statement on the fact so Joe would be seen as they type of guy who always states the obvious.

Things could easily get weird from there, especially with statements like:

Person: I think you have some sort of odd powers.
Joe: You've never noticed anything odd about me.
Person: You're right, but now that you mention it, I think you have some odd powers.
Joe: No, you don't think that.
Person: I don't think what?  Uh...  What were we talking about again?


Joe would have to be very, very careful. In fact, just not talking until he'd really thought something through would be safest.

• Joe: "These are not the droids you're looking for." waves hand – flith Jan 25 '17 at 13:23
• @flith: And, suddenly, the droids in the hovercar change for R5-D4 and TC-14 – Jack Aidley Mar 27 '19 at 13:12

Depends a lot in what he says. Some things are impossible to suspects. But there are others things can make people doubt him.

For example, he says:

• "This year i've made 4 phd careers at the same time. One of them in USA, another in Australia, other in Japan and the last one in Brazil. And of course i've continued being the president of Mexico, and i reached the rank 1 in Tennis and made my Rugby team the world champion." and more things. Maybe it's likely impossible, but if it's true, people would suspect anyway.
• "God talked only to me, and he said 'Joe, take only 2 criatures for each animal species and make a big ark because i will die tomorrow and that's my last wish. And don't tell anyone'", if Joe made all people to notice he isn't crazy, lot of people would be like, "¿Why God will talk only to you?", and of course, anyone can think whatever they want, including suspect him.
• "Tomorrow would be 3 earthquakes and Nigeria will eliminate Germany on Soccer by twenty three goals", and lot of predictions, as stated by ChronoD
• "You are thinking in a 3, and now in a 7, and now in -67.840002, and now in Game of Thrones", if he say that to a lot of people (Worst if he say that to all of them at the same time), there will be somebody who cant doubt him?
• "You will never forget me" and some similar ones. He could break his own powers if he isn't carefull.
• "Hey chief! I've made all of these company work by myself. Anyone made nothing. Only me", there are people who can't be lazy, and can't accept that fact. Even, could doubt from other people but not in himself.... Crazyness would arise as side effect too. The same applies for calling people liers and other things that people care a lot for themselves.

And probably lot of examples like those. However, all suspects can be cleaned by his magical words if he want. And hide all clue.

• You are thinking in a 3, and now in a 7, and now in -67.840002, and now in Game of Thrones Now I suspect YOU, Unicorn Joe. I actually thought about those things when you mentioned them! Spooky. – xDaizu Jan 24 '17 at 7:51

Joe would appear to be psychic / prescient / omniscient. He would make statements about things he couldn't possibly know about, and the cosmos would conform to make the statements true. As a trivial example, Joe could enter a standard ESP test and correctly guess fifty out of fifty randomly-drawn cards. Your description tells us Joe can't even sabotage his own efforts by stating something impossible or improbable -- if he intentionally guessed "ace of spades" when guessing Monopoly properties, he cosmos would retroactively add an "ace of spades" space on the board, or the experimenter would have added "ace of spaces" as bad data to test Joe's psychic powers, and then Joe guesses correctly. Nobody affected by Joe would know that things had changed, because to them nothing has changed. This brings up an important side-effect:

Joe would appear to have dementia, because his memory is not changed by his cosmos-altering power, so Joe's memory would disagree with everyone else's. This would appear to any (every!) observer as hallucinations or psychosis. He might claim act as if humans didn't have five fingers to each hand until a few minutes ago, even if that was always the case.

EDIT: wizzwizz4 correctly points out that anything Joe "claims" will be true. Instead, Joe would do inexplicable acts like trying to pick up an item with his second thumb, writing a cheque using base-12, or buying hats in pairs despite having only one head. If he fails to explain why (especially if he isn't aware of witnesses), he will appear to be acting nonsensical.

Joe would appear to be both gifted and ill, remarkable and pitiable. We would never know Joe alters the past because the past is the only thing we have to measure with.

• The last bolded segment here about dementia and how others would perceive his memories as contradictory to theirs is probably the best way for people to notice something is off about him. This may in turn lead him to be experimented on which could lead to the discovery of said ability. Though in all actuality, all he has to do is say, I am now standing in a different city and science has no records or tests of my abilities and everything is back to 0. – ggiaquin16 Jan 24 '17 at 17:31
• If he claims that humans didn't have five fingers to each hand until a few minutes ago, they won't have. – wizzwizz4 Jan 24 '17 at 17:56

They will notice if Joe wants them to and not if Joe doesn't want them to.

All it takes is one sentence from Joe "Everyone on Earth is always oblivious to my powers." and so shall it be. If Joe were to say "There must be someone who noticed my powers." then that will also become true.

If this is for the plot, then all you need to do is either make Joe paranoid about his powers and mutter the second sentence to himself or make him abuse his power to make everyone not notice it.

Maybe nothing special would happen and Joe would came unnoticed as really quiet and good person :)

As @Murphy stated: If Joe is a human then Joe was once a toddler going through the terrible 2's. Imagine the world view of a child who takes it for granted that anything they say out loud is true. Nobody can ever have made this toddler go to bed if they didn't want to. Nobody could ever have made them do anything because they could just scream "I'm NOT going to bed!"

It is perfect time for lazy universe - Joe is not aware about world much and mainly talk about himself and his close family. And does not want nothing much complicated and elaborated - "I'm NOT going to bed!" "I'm NOT eating that!" ... the easiest way is, that he's just NOT going to bed and eating that just now and nobody is able to force him. But his family knows at the point, that something is wrong with Joe, as other childs are pushed to bed and fed with that usually anyway. And it would not be long before somebody tell something like "I cannot put eyes from you, cause you will make some problems again ..." and Joe scream "I'm NOT doing any problems again" and that is true. From that moment Joe is unproblematic child, does not scream statements that change things, usually does not talk much and when he talks, it is polite, like "I would rather not eat that" (and it is true, he really would not like eating that) but when mother say "But eat it anyway" he would do so (to not make problems again) even if he really hates the food at the moment. And lazy universe have spare itself a lot of changing.

Joe will grow quietly, until he get much better grasp of the wolrd around and himself and found out, that he actually have power to change things, but only if it does not "make problems again". So he have to learn how to formulate his wishes to not make problems and the world slowly turns to really nice place. Some agencies will find eventually, that he have real power, but when they try to missuse him, he reflexively turns them away to "not make problems again" in very subtle and sophisticated ways.

Common people would not realize him as the source of changes, as he prevents it too, but this does not prevent them from feeling good around him while talking about their problems and those problems somehow sorts out itself in some time, in visibly only natural ways (drunken sailor is moved by tears of his wife, as he still love her and stop drinkig too much, then he drinks only ocassionally and a little, while his wife appreciate that and stop yelling on him and cook for him every day, becoming good cook and even starting famous home restaurant so they no longer suffer from powerty. And it is all done by power of love and hard work, no visible magic ...).

:)

That is a pretty unstable power sure everyone will notice something wrong is happening, you should treath what Joe says as Wishes, assume Joe enter in a Bar and says:

The barman offer a beer to Joe.

In the meanwhile in the whole world every person whose name is Joe is offered a beer by a random barman, even if those Joes are not in a bar. A barman was left frozing to death when he suddendly appeared on Mt. Everest while a climber named "Joe Sullivan" was resting on a small platform he saw a barman appearing and offering him a beer, immediatly after the barman realized he would have froze to death.

The fact that truth is really a dangerous practice. Joe is likely will quickly learn to speak in the most possible and precise way, or to possibly don't speak at all, or to speak only through making questions and by never telling something as a affermation.

What if joe says:

If I'm true there's a mountain over there, If I'm wrong there's a sea over there, and I'm wrong.

?

Joe is wrong, then a sea should appear. But then Joe would have been correct, and hence there would be a mountain, but in that case Joe would be wrong.

• "Joe can't affect the fundamental truthiness of his statements, and blatant logical or linguistic paradoxes like 'This sentence is a lie' will either do nothing or randomly flip to one of the potential outcomes." Since he cannot declare a sentence to be false it would be forced to be true. Either nothing will happen or it will take one of the possible outcomes and more than likely a mountain will appear since he is true. – ggiaquin16 Jan 24 '17 at 17:25
• IT is one of the opinions, but honestly only Joe can verify what happens in that case :D – GameDeveloper Jan 24 '17 at 17:55

The potentially world changing entities, of course, will notice. Either in their own right or through the agency of observers acting as their proxies.

They have the chance to make the statement: "Joe will never know or be aware we exist. If Joe even suspects we exist, that thought will be immediately blotted from his mind, leaving no trace in his memory. Nothing Joe changes will change or affect us and our observers. Joe will never say anything to affect or change us."

This safeguards the other world changing entities. Now they might decide to set up a control to Joe's world changing activities. This can be any ordinary person like Fred or Marge whose memories will be engineered by the other world changing entities to be unaffected by Joe's world changing statements.

The only other way has already been proposed by Matt Bowyer and would have been by Erik (if Matt hadn't struck first). Namely, that Joe himself nominates someone to remember despite his changes. Thanks, guys, for beating me to this solution too.

There was one other faint possibility worth considering. That, irrespective of what Joe says, the world changes require his intention about what changes. There could be things and people who exist in our world about which or whom Joe is unaware. If so, when the world changes including its past these people and things remain unchanged.

For example, a Mongolian taxi driver with a PhD in nanotechnology (a category of person Joe had no inkling existed and therefore wasn't changed by Joe's latest edict) might wake up to discover Joe was now president of the USA when yesterday it had been Bernie Sanders.

If the world changes were mediated by 'something' that had to interpret his words about what world change he wanted, and possibly had to reconcile this with his intentions. There is the possibility that some persons or things will be left behind unchanged. perhaps over time as more and more the world is transformed by Joe less and less will remain behind unchanged. In which case, during the early phases of Joe's world changing he might be confronted by Mongolian taxi drivers waving their nanotechnology PhD degrees in his face and demanding to know why the world keeps changing.

"Don't worry," said Joe. "I'll soon fix it."

The most important part to me comes in you second edit:

Edit II: Joe is, in this case, being used as a proxy for various potentially world changing entities in this world.

So what does your universe do, if Joe1 says, that earth do not have (and never had) three moons, while Joe2 is visiting all of them by his special power? Well you gave kind of an answer for this:

Joe can't affect the fundamental truthiness of his statements, and blatant logical or linguistic paradoxes like 'This sentence is a lie' will either do nothing or randomly flip to one of the potential outcomes.

If that happens in that case, people will notice something odd, because the universe created by Joe1 does not take into account the changes of Joe2. These changes have a chance to happen randomly, instead of Joe1 changes, which will create unfitting situations.

If you now come to the point, that only changes happen, when they do not contradict the changes of other "Joe", you would limit the abilities of these entities by several magnitudes, and create the necessity for this "magic power" to know every statement which any Joe would ever make to check for inconsistencies.

• Unless the multiple Joes are themselves immune to the other Joes' powers, any number of Joes saying things one after the other is no different than one Joe making conflicting statements one after the other. Each statement changes reality and all the other Joes along with it. You only run into the problem you are describing if multiple Joes make simultaneous and conflicting statements. – Mr.Mindor Jan 25 '17 at 21:24

Joe says, “you beleive me, right?” or “nobody ever discovered my secret power.”. So it’s up to him.

No other reasoning is possible for this answer, since Joe can always override the probable with his statements.

• Interesting. “you believe me, right?” is a Question, so probably nothing will change. – Julian Egner Jan 24 '17 at 7:35
• @JulianEgner Intent means a lot when he makes statements(...) – xDaizu Jan 24 '17 at 7:49
• Hm. right. In this setting, he gets the intended effect, not the spoken effect. (Every programmer knows the difference...) – Julian Egner Jan 24 '17 at 9:10

Every time Joe says anything, it effectively leads to creation of alternative reality that lives according to Joe's wishes. If there are no traces of previous reality left (except perhaps in Joe's memory), then the answer is no - people can not notice that Joe has this kind of power. Nobody would have any knowledge of previous reality that existed before Joe said his last sentence.

I would, however be very careful if I were Joe. Some innocent phrases like "It's a slow day today" have potential of ending the universe as we know it.

There are several ways a person who Joe has not explicitly made aware of the situation can become aware of it, so long as Joe does not prevent this from happening.

Some of Joe's comments may require others to observe changes in the universe rather than have it appear to always have been so:

"There was a park here a minute ago, but now it's an airport."

Because for the statement to be true, an observer would have to know that the previous state was true, and would surely remember it. Memory alteration would cause the statement to be false for that person.

If Joe's comments are not contradictory of present reality, no rewriting will take place and his ability to state what will happen would be deducable due to probability.

"I'm going to get four straight flushes in a row!

"That dog is going to jump over the car, land in a roll, and come up doing a moonwalk while singing showtunes!"

"Everyone who sees this answer is going to upvote it!"

On seeing anything incredible happen right after he said it, it would immediately draw attention to how unbelievably coincidental it was. At first it would appear to be predictive rather than causative, but that could eventually be figured out.

Even mundane comments about future events will tip people off that Joe has an uncanny ability to state what's going to happen. One or two comments would not be surprising, but if everything he said always turned out to be true that would be enough for people around Bob to become curious and eventually discover his ability.

This whole situation depends, for obvious reasons, on when the universe decides that his statement is over. For instance, let's suppose that Joe states, "I want to be a..." and before he can finish, he is turned into the letter A. Maybe the universe waits for him to pause a certain amount of time, as if he has finished his sentence? Maybe he simply states a keyword as a method of ending? Obviously, this is an important bug/feature (depending) of his power.

As an add-on to the previous paragraph, this power would also depend on the level of ambiguity of Joe's statements. If Joe stated, "I am a vehicle," then Joe may be any random vehicle, even those not invented yet, depending on the universe's definition of vehicle. Joe may wish to learn a different language using more precise nouns and adjectives, or he may simply state that he has already invented such a language and use that instead.

I don't think people would notice, given this situation, though, because that's the way things have always been. If somebody else had the power that their memory was also inviolable, then he could say that he/she has never existed, and then that person no longer exists.

His teachers would notice, due to his getting 100% on every test. Or, at least, every test where random answers don't affect fundamental physics.

In a maths test, if he answers "What is 1+2?" as "4", then either he'll get it wrong (can't change fundamental physics) or the symbols "3" and "4" will switch. If it's the former, maybe he won't get 100% in maths.

But, in something like a history test, with questions like "Which Prime Minister took Britain into the second world war?", if he answers "Tom Marvolo Riddle" then Neville Chamberlain will always have been called Tom Marvolo Riddle.

• But then, would he want a 100% in maths if the symbols switched? Maybe he'd want a 001% :P – Michael Mar 27 '19 at 10:36