The Daily WTF: Curious Perversions in Information Technology

2012-10-01 Reply Admin

It's easy to prove that time travel is impossible.

If time travel is possible, then sooner or later someone will manage to invent a time machine. Once they do, sooner or later others will manage to copy it, and eventually there will be many time travellers. It may be centuries, millenia, or aeons from now before time travel is invented, but if it is possible, than inevitably it will be, sooner or later.

Maybe some of these time travellers will try to hide their existence, but, again given sufficient time, sooner or later someone will come along who decides not to hide his existence.

Even if all human life comes to an end one way or another, if there is life on other planets, sooner or later they will to the Earth with their time machines.

And sooner or later these travellers will decide to visit the 21st century.

So ... where are they?

As I see it, the only possibilities are: (a) Time travel is impossible. (b) Humanity is destroyed before it manages to invent time travel AND there is no other life in the universe. (c) It is somehow inevitable that time travellers hide from the people in the past they visit, 100% of the time.

2012-10-01 Reply Admin

Minor nitpick on the Physics discussion - The laws of Physics *aren't* actually the same if you flip the direction of time (t -> -t). It used to be assumed that they were, but in 1964 James Cronin and Val Fitch found a violation of that symmetry, in the weak interaction (which, it turns out, works slightly differently forwards to backwards; for which they won the 1980 Nobel Prize for Physics). (http://en.wikipedia.org/wiki/CP_violation)
They proved it by reversing time, right?

Luckily you don't need to reverse time. Antiparticles are basically particles that 'go backwards in time' (that's more or less a statement of CPT-symmetry) so you can look for CP-violation by comparing particles to their antiparticles, which is pretty neat. (See Also)

2012-10-01 Reply Admin

SEMW:
Minor nitpick on the Physics discussion - The laws of Physics *aren't* actually the same if you flip the direction of time (t -> -t). It used to be assumed that they were, but in 1964 James Cronin and Val Fitch found a violation of that symmetry, in the weak interaction (which, it turns out, works slightly differently forwards to backwards; for which they won the 1980 Nobel Prize for Physics). (http://en.wikipedia.org/wiki/CP_violation)
They proved it by reversing time, right?

Luckily you don't need to reverse time. Antiparticles are basically particles that 'go backwards in time' (that's more or less a statement of CPT-symmetry) so you can look for CP-violation by comparing particles to their antiparticles, which is pretty neat. (See Also)

Umm, it's quite a leap from saying "the behavior of particle A over time is in some ways the opposite of the behavior of particle B over time" to saying "this proves that such-and-such will happen if you could travel backwards in time".

2012-10-01 Reply Admin

I was thinking of majoring in time travel when I was in college. But my faculty advisor convinced me not to. He said it was a very unpromising field. There's no future in it.

2012-10-01 Reply Admin

jay:
Umm, it's quite a leap from saying "the behavior of particle A over time is in some ways the opposite of the behavior of particle B over time" to saying "this proves that such-and-such will happen if you could travel backwards in time".

The comment wasn't handwavy because the Physics itself is handwavy, it was handwavy because this is tdwtf and not a QFT course, so I went for something brief and non-mathematical. CPT symmetry isn't a kinda-neat-but-dodgy idea that someone came up with just out of noticing that antiparticles sorta look like regular particles going backwards in time. It's a mathematically provable symmetry of any Lorentz-invariant quantum field theory. If you flip C & P (i.e. particles -> antiparticles and flip parity), you get the same Physics as if you flip T (i.e. go backwards in time). If you want to delve into maths yourself, feel free: http://arxiv.org/abs/math-ph/0012020

InsaneCoder · 2012-10-01 Reply Admin

jay:
The advantage of the old INI files was that if application A decides to fill its INI file with a bunch of "random crap" as you put it, that's his problem. It doesn't affect me as the author or user of application B. Each app is responsible for its own mess.
As I understand it, Microsoft invented the registry because there was so much junk being put it win win.ini file and they felt they needed to clean it up. But instead of eliminating the junk from the win.ini, they decided to institionalize putting junk in it.

It seems to me the intelligent solution would be to say that the win.ini or whatever replaced it can ONLY have system-level data. The only data related to an application in a win.ini should have been the name, path to the exe, path to the uninstall program, and a list of the extensions that it knows how to open. Maybe you can think of one or two other things that might be appropriate. Any other data the app needs should be in a data file private to that app and stored in its own directory. This would be clean and easy to manage.

Indeed, the registry was such a bad idea that OS X implemented a system that looks amazingly similar: defaults. But that's OK, because it's Apple, not Microsoft, right? :-)

2012-10-01 Reply Admin

InsaneCoder:
jay:
The advantage of the old INI files was that if application A decides to fill its INI file with a bunch of "random crap" as you put it, that's his problem. It doesn't affect me as the author or user of application B. Each app is responsible for its own mess.
As I understand it, Microsoft invented the registry because there was so much junk being put it win win.ini file and they felt they needed to clean it up. But instead of eliminating the junk from the win.ini, they decided to institionalize putting junk in it.

It seems to me the intelligent solution would be to say that the win.ini or whatever replaced it can ONLY have system-level data. The only data related to an application in a win.ini should have been the name, path to the exe, path to the uninstall program, and a list of the extensions that it knows how to open. Maybe you can think of one or two other things that might be appropriate. Any other data the app needs should be in a data file private to that app and stored in its own directory. This would be clean and easy to manage.

Indeed, the registry was such a bad idea that OS X implemented a system that looks amazingly similar: defaults. But that's OK, because it's Apple, not Microsoft, right? :-)

I have only the most casual experience with Apple and OS X, so I cannot express an opinion. But the idea that Apple might have done something dumb does not strike me as inconceivable. I don't have an irrational hatred of Microsoft. I have a rational hatred of dumb ideas.

2012-10-01 Reply Admin

SEMW:
jay:
Umm, it's quite a leap from saying "the behavior of particle A over time is in some ways the opposite of the behavior of particle B over time" to saying "this proves that such-and-such will happen if you could travel backwards in time".

The comment wasn't handwavy because the Physics itself is handwavy, it was handwavy because this is tdwtf and not a QFT course, so I went for something brief and non-mathematical. CPT symmetry isn't a kinda-neat-but-dodgy idea that someone came up with just out of noticing that antiparticles sorta look like regular particles going backwards in time. It's a mathematically provable symmetry of any Lorentz-invariant quantum field theory. If you flip C & P (i.e. particles -> antiparticles and flip parity), you get the same Physics as if you flip T (i.e. go backwards in time). If you want to delve into maths yourself, feel free: http://arxiv.org/abs/math-ph/0012020

Okay, I'll have to read that. But maybe I'm missing something here, but it seems to me that, by definition, if you go backwards in time, all processes would have to operate in reverse. How could you possibly say that if you go backwards in time, some processes would still go in the same direction? It's a logical contradiction. I'm hard pressed to imagine what argument could convince me of such a non-sensical proposition. Like, suppose you told me that you have some very complex mathematics that proves that north is the opposite direction from east or that triangles have four sides. Even if I can't find a flaw in the math, I doubt I would be convinced, because those statements are false by definition.

2012-10-01 Reply Admin

da Doctah:
Tim:
Jerry:
Bill:
Name:
Someone please explain why that sign at the London Olympic Park had to be shaped like a cloud
Duh. Cloud computing. It's the new thing. Please try to keep up.
Actually, cloud was the new thing several years ago. Now it's the old thing. Please do try to keep up.
OK smartypants, what's the new new thing? And make sure it's from next week, because this week is pretty much over.
We time-travelers aren't allowed to reveal too much about your future, so I'm afraid I can't give you a detailed answer.
I can only offer one piece of advice: take up hedgehog breeding.

Was 'Ere - 2036 (or was that 2001, I forget)

2012-10-01 Reply Admin

Gary Olson:
The bus route can be explained by pure administrative deviousness. The bus routes could not be designed such that the driver was returned to the depot during a normal shift. The PHB had the intern create a time loop so he could get an extra 30 minutes work from the driver; and get him back to the yard without paying overtime. And he sent the intern thru the loop first as a test; and never paid the intern because the time loop had not been created yet. Pure management evil genius.

or perhaps when the route changed number they aligned the right up route with the wrong down route that is, they used two timetables and joined them in the wrong spot....a minor WTF at best. Likely it was because an extra route had been inserted in one direction....

2012-10-01 Reply Admin

jay:
SEMW:
jay:
Umm, it's quite a leap from saying "the behavior of particle A over time is in some ways the opposite of the behavior of particle B over time" to saying "this proves that such-and-such will happen if you could travel backwards in time".

The comment wasn't handwavy because the Physics itself is handwavy, it was handwavy because this is tdwtf and not a QFT course, so I went for something brief and non-mathematical. CPT symmetry isn't a kinda-neat-but-dodgy idea that someone came up with just out of noticing that antiparticles sorta look like regular particles going backwards in time. It's a mathematically provable symmetry of any Lorentz-invariant quantum field theory. If you flip C & P (i.e. particles -> antiparticles and flip parity), you get the same Physics as if you flip T (i.e. go backwards in time). If you want to delve into maths yourself, feel free: http://arxiv.org/abs/math-ph/0012020

Okay, I'll have to read that. But maybe I'm missing something here, but it seems to me that, by definition, if you go backwards in time, all processes would have to operate in reverse. How could you possibly say that if you go backwards in time, some processes would still go in the same direction? It's a logical contradiction. I'm hard pressed to imagine what argument could convince me of such a non-sensical proposition. Like, suppose you told me that you have some very complex mathematics that proves that north is the opposite direction from east or that triangles have four sides. Even if I can't find a flaw in the math, I doubt I would be convinced, because those statements are false by definition.

At the North Pole SOuth is opposite (and perpedicular to) SOuth.....

2012-10-02 Reply Admin

jay:
How could you possibly say that if you go backwards in time, some processes would still go in the same direction?

...No-one's said anything of the sort.

What I said was that firstly, antiparticles are basically particles that 'go backwards in time'. So if you flip t to -t (and mirror-image everything), what were particles now look like antiparticles, and what were antiparticles now look like particles.

CP violation comes in because the laws of Physics, it turns out, don't look exactly the same if you do this. In other words, particles and antiparticles aren't quite exact mirrors of each other. E.g. some particles decay slightly faster than their antiparticles do.

But no, it's not true that "some processes would still go in the same direction" if you flip t to -t.

So, to be absolutely clear: If you flip C & P (i.e. particles -> antiparticles and mirror-image everything), OR you flip T (i.e. go backwards in time), you get Physics that works slightly differently to what you had when you started. But if you flip all three of C, P, and T (particles -> antiparticles, parity inverted, and go backwards in time), you do get back to exactly the same physics you had where you started - which means that 'flipping C and P' and 'flipping T' are equivalent operations.

(And here are the relevant wiki articles again).

2012-10-02 Reply Admin

SEMW:
jay:
How could you possibly say that if you go backwards in time, some processes would still go in the same direction?
...No-one's said anything of the sort.
What I said was that firstly, antiparticles are basically particles that 'go backwards in time'. So if you flip t to -t (and mirror-image everything), what were particles now look like antiparticles, and what were antiparticles now look like particles.

CP violation comes in because the laws of Physics, it turns out, don't look exactly the same if you do this. In other words, particles and antiparticles aren't quite exact mirrors of each other. E.g. some particles decay slightly faster than their antiparticles do.

But no, it's not true that "some processes would still go in the same direction" if you flip t to -t.

So, to be absolutely clear: If you flip C & P (i.e. particles -> antiparticles and mirror-image everything), OR you flip T (i.e. go backwards in time), you get Physics that works slightly differently to what you had when you started. But if you flip all three of C, P, and T (particles -> antiparticles, parity inverted, and go backwards in time), you do get back to exactly the same physics you had where you started - which means that 'flipping C and P' and 'flipping T' are equivalent operations.

(And here are the relevant wiki articles again).

Hmm, I'd have to go back over the thread, I guess I'm mixing your posts together with posts from someone else, and missing the point that you were trying to make. (Okay, I don't actually care enough to go back over the thread and re-read all the posts. If you say that that isn't what you said, I'll take your word for it that I either misunderstood or it was someone else.)

Watson · 2012-10-02 Reply Admin

Stev:
TarquinWJ:
Cbuttius:
Also ... I want that bus system to run here, since it would allow you to go back and remove all those mistakes you wish you had never made. And become your own grandfather (though you may have to ride the route quite a few times for that).

I don't think it is possible to become your own grandfather, even with the ability to time travel. For you to be your own grandfather, you would have to have existed to impregnate your grandmother in the past - however, you couldn't possibly exist until you were born and for you to be born, you would need to have had a biological grandfather.

Unless of course you travelled back in time so that you could exist prior to your birth. I don't know about yours, but I'm pretty certain that neither of my grandmothers stopped to verify that the blokes they were getting hitched to weren't time-travelling descendants.

shadowman · 2012-10-03 Reply Admin

Apparently, none cares about anything besides casinos

I keep looking at the image and re-reading this sentence, and it makes less sense every time.

2012-10-03 Reply Admin

Remy Porter:
Actually, this isn't entirely true. Much of physics is "time invariant". So if you hit the "reverse" button to rewind time- the cream and the coffee would stubbornly stay mixed, uranium would continue to decay and never undecay, etc.
Entropy always increases, no matter which way the arrow of time is pointing.

At the quantum scale, physics are time invariant in the sense that if you looked at something, whether it was played forward or backward, you couldn't tell which way it was! At the quantum scale of things, cream jumping out of coffee is no different than cream going into the coffee. Neither is impossible. It doesn't violate any thermodynamics, it's just pretty hard to get things to behave that way.

2012-10-04 Reply Admin

Remy Porter:
But if that rock is a piece of uranium, as it falls I'm going to see the uranium decay. Positive delta-t. As I reverse it, with negative delta-t, the uranium continues to decay. It doesn't reverse its decay.
That's what I'm talking about.

Huh? Imagine Uranium's decay as a movie, where you see the particles coming out, the nuclei transforming, etc. When you play it back, the particles are flying back towards the nuclei and fuse into original stuff. If that's not "reversal" of the decay, I don't know what is. You're using some completely weird definition of "delta t". The definition is simple: if something happens with "positive" delta-t, to obtain it with negative delta-t you set things up as if you were going to play it back in reverse.

For fission products, simply reverse their momentums and let go. You'll get the original atom back -- with a certain probability amplitude, of course, there's no magical "in playback it's all 100% likely" thing going on. Unless I'm mistaken, those were Feynman's own words, and I kinda trust the guy.

The reason why backwards-playback won't reverse the time as seen macroscopically is that the original configuration that you try to play back towards has a very small probability amplitude. If you look at things in reverse playback, all you know is that you observed a certain course of events that has a very small overall probability of happening. Not an impossible course of events at all, mind you!

Same thing, really, as when you observe a certain course of events when played forward -- it's one of a gazillion possibilities, after all. That's also why entropy seemingly always increases: it doesn't have to, it can even decrease (cream coming out!), but it doesn't happen often, that's all. With a large system like coffee and cream, the probability of entropy decreasing is so slim that ignoring it is the only sane thing to do.

toshir0 · 2012-10-04 Reply Admin

Cbuttius:
Going back in time to 1947 would be nice for another reason: I could go and watch Charlton win the FA Cup final...

Better : you could go ask Max Planck to answer Remy :

Remy Porter:
Obviously, there are no time reversers, so there is no experimental confirmation of this specific statement. But there are deep mathematical reasons why the best explanations for things like entropy are time invariant. Our theories of entropy are well tested and cover many cases, and they predict time invariance.
It leads to one of the bigger quandaries of modern physics: if entropy increases regardless of the direction of time, why does the arrow of time proceed in only one direction? Why does causality flow from cause to effect?

2012-10-22 Reply Admin

All I had to do was put aluminum foil in the microwave.

The Time Travelling Bus

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