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Comment by leni536 | Hacker News Reader

OK, so tldr: If you can't define a partial ordering between events (ie. "earlier than" as in A can cause B, "later than" as in A can be caused by B, "same time" as in there can be no causal relationship between A and B), then time as defined in B-theory can't exist.

So what? What are the consequences?

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Nothing! It's fun thinking about it.

I think, he's trying to say that "time" is really not a thing, but rather our perception and understanding of time makes it a thing. What we should see as time is actually some flow of causality. You cannot map "earlier/later than" or "same time" to causal reality, those qualities only refer to time as a scale, not as a natural occurrence of causality order. Or so I think.

In other words, time emerges from causality (and our observation of it), not the other way around. Is that right?

If there is no way to define an unambiguous time ordering, then you cannot use a "flow" of time picture to describe time. In other words, despite the everyday perception of time as something that marches ever onward, in reality we live in a "block" universe where nothing moves.

Or so was supposedly Gödel's argument.

Also, our own perception of time depends on this "block universe where nothing moves" changing and enabling some synapses and chemical reactions in our brains. Hence, a change in this block could take an "eternity" (of real time, if there were such a thing) and we would only notice it as an infinitesimal moment.

There are some cool "practical" consequences like building time machines. But you need some serious civil engineering equipment: First take a mass the size of a star. Squeeze it into a thin really really long cylinder, make it rotate very fast ... and boom! You can travel back to the day you created it.

[0] http://adsabs.harvard.edu/abs/1976PhDT........61T [1] https://en.wikipedia.org/wiki/Tipler_cylinder

From the article, "[this] casts doubt on the reality of time in our world".

If the order is undefined, then how can you say I'm late?

The order between (1) "you being late" and (2) "you departing home at 09:05" is undetermined, but the events themselves aren't.

Or: it doesn't matter in which order you write the events of a story, as long as the events themselves are in order. The author is not bound by the timeline of the story.

Left as an exercise for the reader.

For example how this would correlate with the quantum entanglement, where the supposed spooky action is described as instantaneus, so this has no time to factor in. Not quite able to determine, which particle was actually seen/observed first so that you can have a causality flow.

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