This sentence is falseThis is the classic Liar Paradox. I was surprised to read philosophers still can't agree on a way out of this paradox... Having studied quantum physics the answer seems obvious.
The observer effect (often confused with the uncertainty principle - even by its discoverer Werner Heisenberg) means it is not possible to measure certain properties of some systems (especially of elementary quantum particles) without affecting the system in some way that alters what is being measured.
An object in a dark room - you can't see it without turning on a light.
At a non-quantum level the object could be a thermometer and the light a very powerful light. You can't read the temperature without the light, but in turning the light on you'll heat the thermometer.
If the object is truly minuscule the light photons themselves will alter the position and direction of the particle. Without the light you don't know where it is, and with the light you don't know where it was.
In some cases it is possible to negate the observer effect by calculating the exact effect the observer had on the system and working back. At a quantum level this is simply not possible when measuring some properties, leading to uncertainty.
Language itself has an observer effect. Language means nothing unless it can be understood by the observer.
In processing the text to understand what is written the observer's understanding of what is written can be altered by what is written.
In some respects the liar paradox is just a special case of dynamic reprogramming of the language.
The following sentence is non-paradoxical but underscores how the reader's understanding of a sentence can be altered by the processing of the sentence.
For the remainder of this sentence the word "on" means "under"; the cat sits on the table.Where does the cat sit?
If you can't process the sentence then you wouldn't know anything about the cat or the table.
If you can process the sentence you'll believe the cat sits under the table, despite the sentence actually saying the cat sits on the table.
Similarly, the liar paradox alters the reader's understanding of what they're reading by changing the meaning of the sentence as it is being read. Only in this case the altered meaning is meaningless.
The reader starts from a default position: that what they're reading will be meaningful and therefore true; but are then told what they're reading is false.
This is not a paradox in the traditional sense because it does not defy logic or reasoning. It's more like circular reasoning, with the reader starting from a position that what is written is meaningful and therefore true but being told that this particular sentence is false and therefore meaningless.
For the remainder of your life the word "on" means "under"; the cat sits on the table.Now read the sentence again. Where does the cat sit now?!
On the first time of reading, the answer should be "on".
On the second time of reading, the answer should be "on".
Why? Because after the first reading you are instructed that "on" means "under" so even though the cat is under the table you'd express that as "on".