A question about time travel

[Bohandas]

So, a pedantic note: it is not a Hypothesis. Nor is it a Theory. It is called an "Interpretation" for a reason.

Hypotheses and Theories can be tested. The Many Worlds Interpretation is non-falsifiable. It is a sort of narrative that is consistent with the laws of quantum mechanics, but is not testable by those laws.

You mean it's impracticable to test. The quantum suicide experiment can test it, but requires that the experimenter bet their life on it, and provides meaningful information only to the experimenter/subject themself.

Furthermore, other interpretations have had actual experiments done on them, such as the walking droplet experiment on pilot wave theory

 

[Umbran]

You mean it's impracticable to test.

Please, in the future, refrain from telling me what I mean.

I mean that it is impossible, even in principle, to test. The MWI makes no testable predictions different from any other interpretation of quantum mechanics. If you were to travel in time or between quantum realities, you'd not be able to tell the difference between MWI and any other interpretation.

 

[Bohandas]

Consider this thought experiment. You're put under general anaesthesia and hooked up to several sets of apparatus that each have a 50% chance of going off and killing you based on whether a certain atom decays. After an hour all untriggered devices disarm and you are woken up if you are still alive. Now, 30 such devices is sufficient to bring your chances of survival to under 1 in a billion. But under the many worlds interpretation you will ALWAYS wake up, no matter how many devices are added, because you will not experience the other 999999999 (or however many, depending on the number of devices) universes where you die. Add enough devices and the most reasonable explanation for waking up will eventually be that the many worlds interpretation is true. Of course, this tells others nothing hecause unlike you they DO experience the universes where you die, and if many worlds is not true than it tells you nothing either, and it can't provide absolute proof with a finite number of devices, but it nonetheless a test, however impractical. You go in with the null hypothesis that you will not wake up, (which is implied with a certain degree of probability by single world interpretations such as copenhagen and debroglie-bohm, but for you and only you is not implied by many worlds). If you wake up then this null hypothesis is falsified which supports the many worlds interpretation over single world interpretations.

 

[Umbran]

Add enough devices and the most reasonable explanation for waking up will eventually be that the many worlds interpretation is true.

With respect, when I speak of something being "non-falsifiable", I am speaking in the sense used in scientific testing. "Most reasonable explanation" is not sufficient. This is an issue of absolute logic, not "most reasonableness"

You are also approaching it backwards - you are providing a test that would provide evidence that MWI is correct. We are talking about a possible test that it is incorrect.

In your scenario, the person can die or the person can live. Both results are consistent with the MWI - one is merely very unlikely. So, if the patient lives or dies you can say, 'This fits the MWI'.

We need a scenario for a test that has a result that is not consistent with the MWI.

However, the MWI by definition includes all possible results. If it can happen, it happens in the MWI. Any result you could possibly get from any experiment is consistent with the MWI - so it is not falsifiable.

 

[Bohandas]

Put it this way, it would falsify copenhagen and most of the other ones

And if MWI were correct, the results would also be reproducible

 

[Umbran]

Put it this way, it would falsify copenhagen and most of the other ones

No. Because waking up is still possible under Copenhagen. It is just very unlikely. Copenhagen says you'd go through many attempts, but eventually get one that gets through.

And, by the way, every piece of electronics using semiconductors effectively already does this test.

 

[LuisCarlos17f]

I thought about time travel and some fictional experiments.

1st Experiment: a gold ingot, from the future is sent to the past to be both fused. What would happen?

2nd one: A robot travels from the future to the past with these orders; going to a special room with a wall. If this wall is blue it has to be red-colored painted, if it's red color then to be blue-colored paint, if it's a different color then randomly to paint red or blue. After the time travel: what color is the wall?

---

To avoid headaches about time travels in fantasy fiction, with ghost and deities I though something. The alteration of the past by the time travelers are possible, at least partially. The past isn't really erased and rewritten but more like using adding a layer or correction fluid. Then it would be something like "Schöringer's cat", yes and no at the same time. In my games, theses uchronies or alternate timelines, with changed little details are practically pocket universes. But if the alteration of the past is too radical, for example killing an important Historical character, then the things are different. Let's say these demiplanes need special "anchors" in the space-time continuum. When different time-traveler factions fights each other to change or keep the past, the key are these anchors. Without these the alternate timeline doesn't disappear, but suffer "planar holes" allowing cosmic gates to be opened by potential alien invaders, for example the Far Realm (D&D). These uchronies become
dream, or nightmare, realms. This could cause planar conflicts, for example nazis from the 4th Reich sending spies to an alternate timeline where Arthur, prince of England survived the sweating sickness and became king. Later Spain and England formed one empire (Anglican schism never happened because Henry VIII was not king but his older brother Arthur) and technologic advance arrived sooner.

 

[Umbran]

I thought about time travel and some fictional experiments.

1st Experiment: a gold ingot, from the future is sent to the past to be both fused. What would happen?

There is, of course, no single answer to this. It depends on what kind of time travel you've chosen. Same for your other experiment.

2nd one: A robot travels from the future to the past with these orders; going to a special room with a wall. If this wall is blue it has to be red-colored painted, if it's red color then to be blue-colored paint, if it's a different color then randomly to paint red or blue. After the time travel: what color is the wall?

Note that "after the time travel" is ambiguous. For example:

1968 - the wall is built, and painted grey.

1970 - a robot appears from the future and paints the wall

2025 - a robot is sent back to 1970 to paint the wall.

When you say "after the time travel" do you mean 1971, or 2026?

Your scenario also needs the wall to be some particular color when it was built. If we do not know that, we cannot answer the question. We also have to talk about this overall history of the wall - if someone paints it in 1999, that changes the overall result.

 

[LuisCarlos17f]

Could happen in the first experiment anything like in the movie Timecop (it's a total spoiler about the end of the movie)the villain from the past is tricked by the hero and when past and future version of the villains are together... bye,bye

The wall from the second experiment starting being gray, the robot from the future arrives and paints the wall, maybe blue. Then the scientific group sends other robot to the past, and then the wall is painted red. What happens if the first robot travels to the past to paint the now red wall? Maybe the wall is both colors, not mixed, but more like a hologram picture changed when you walk two steps. Like the famous Schöringer's cat but this time the wall is totally blue-colored and totally red-colored simultaneously.

 

[Ulfgeir]

The wall from the second experiment starting being gray, the robot from the future arrives and paints the wall, maybe blue. Then the scientific group sends other robot to the past, and then the wall is painted red. What happens if the first robot travels to the past to paint the now red wall? Maybe the wall is both colors, not mixed, but more like a hologram picture changed when you walk two steps. Like the famous Schöringer's cat but this time the wall is totally blue-colored and totally red-colored simultaneously.

Both robots appear simultaneously and start working from separate directions, and meet in the middle, each painting in separate colours?