Posts
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The Blogging Gauntlet: May 18 - More Time Travel Password Theorizing
CommentsThis is part of The Blogging Gauntlet of May 2016, where I try to write 500 words every day. See the May 1st post for full details.
This builds upon the ideas from yesterday’s post. Read that one first.
First off, here’s some trivia I learned from the TVTropes page on trust passwords. Harry Houdini and his wife Bess developed secret passphrases which he promised to say to her if he found a way to contact her from the afterlife. After his death, Bess used those passphrases to debunk several spirit mediums. Or, as put by MagicPedia, “Bess began the tradition of holding a seance to see whether Houdini could escape from death.” None of the spirit mediums ever convinced her.
Can I just say: this is totally badass. I never realized time travel passwords could also be used to authenticate yourself from the dead.
(Also, MagicPedia implies she did this as a coping mechanism for her loss, instead of as a way to debunk mystics. I like the latter interpretation more.)
Anyways, so I’ve been thinking about the security of time travel passwords. Suppose you’re kidnapped, and your kidnappers are trying to coerce you to reveal your time travel password. What do you do? Obviously, you could lie about your password. However, this may not help you. If your kidnappers can verify whether messages they sent into the past have changed the present, they’ll know you’re lying.
This doesn’t mean you shouldn’t create a time travel password. It still gives you some security, and if you are kidnapped, you always have the option of giving the adversary your password.
In some ways, this is the best it ever gets. Here’s the quick argument. Any time travel authentication scheme must have a way to convince your past self a message is from the future. This is true by definition. Otherwise, even when you’re sending a message of your own free will, your past self could reject your messages. In other words, every authentication scheme must have some way to let people through the door. If kidnappers have convinced you to cooperate with them, you’ll always be able to open the door for them. There’s no way around it.
Still, there’s room for improvement. Suppose I accidentally say my time travel password out loud. Anyone present can now pretend to be me from the future. And importantly, I have no way to tell my past self their time travel password is no longer secure. Time travel passwords are actually less secure than regular passwords! If we reveal our password in real life, we can request a password change, but this doesn’t work for time travel. You can’t retroactively change your memory! You’re screwed!
(Would this be a bad time to mention I’ve never seen Back to the Future? I know, I know, I’m sorry.)
At best, you can send a message ASAP telling your past self to change their time travel password. But, that assumes you get there first. If you get there 2nd or 3rd, you’re sunk. By that point, your past self has had years to act on malicious information. Who knows what could happen?
An ideal time travel auth-system should minimize the danger from revealing your password. I haven’t thought about it for long, but one option is two-factor authentication. Require every message to come with both a password and a physical token that only you own. That way, anyone who learns your password can’t fool your past self.
Unfortunately, this assumes you can send objects back in time, which might not be true. There’s another issue too: you’re not getting your physical token back after sending it to the past. If you want to send more than one message to the past, you’ll need a new token for each one.
At this point, we’re running into the usability vs security issue. Yes, if you try hard enough, you can make more secure time travel authentication schemes, but at some point it’s not worth the effort to implement them, and theorizing about them is just an interesting exercise. Personally, I’m going to stick to passwords, because they’re good enough for me.
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The Blogging Gauntlet: May 17 - What's Your Time Travel Password?
CommentsThis is part of The Blogging Gauntlet of May 2016, where I try to write 500 words every day. See the May 1st post for full details.
As far as I know, time travel doesn’t exist. However, that doesn’t mean there’s nothing interesting to say about it. In fact, you can do a lot of theorizing about models of time travel.
Today, I made a time travel password. What I’m going to do is detail the argument for why everyone else should make one too.
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Suppose we’re living in a world where time travel is possible, and that furthermore time travel will be invented within our lifetime. I know this is a huge assumption, but bear with me for a moment.
A world where people can transmit information to past versions of themselves is very hard to predict. The nature of that world depends on the model of time travel used, but the potential gains of time travel are huge.
However, that means the potential losses of forged future messages are also huge. If you’re in a world where time travel is possible, the strangest requests in the world can be explained away by saying the future depends on it. What makes decision making tricky is that it’s almost always done under uncertainty. Time travel removes that uncertainty, giving a perfect oracle towards achieving the best outcome. Or, if a message is forged, a perfect oracle towards achieving the worst outcome.
To prevent this, you need an authentication scheme that verifies future messages come from you. Hence, time travel passwords! In the present, you pre-commit to adding your time travel password to any message sent to a past version of you. That way, if you ever receive such a message, you can verify that message is legitimate.
Importantly, you never, under any circumstances, write down your time travel password or speak it out loud. After the password leaves your head, it’s no longer secure. As a corollary, every time travel password is one time use, and you must create a new one whenever you receive a future message.
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There’s a very natural objection to this: isn’t time travel exceedingly unlikely? Why should I waste my time making a password for non-existent technologies?
Well, consider the following.
- Creating a time travel password takes less than a minute.
- If time travel is never invented, you lose one minute of your life.
- If time travel is invented, you prevent a large class of attacks that could be made against you.
The expected utility is vastly, vastly in favor of making a time travel password. I’ll fully admit this argument is a variant of Pascal’s mugging, which you might reject for one reason or another.
Here’s my counterargument. Yes, maybe I’m mugging you out of one minute of your time. However, the value of one minute of your time is very, very low. And even if time travel is never invented, you get to tell people you have a time travel password! How awesome is that? You can explain this very argument, or link to help increase my view counts (nod nod, wink wink).
Having a time travel password makes you a more interesting person, and that’s surely worth the one minute of time it costs you.
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The Blogging Gauntlet: May 16 - Memorable Quotes
CommentsThis is part of The Blogging Gauntlet of May 2016, where I try to write 500 words every day. See the May 1st post for full details.
What makes a quote memorable? What makes it tick?
I don’t have a good answer for this. And furthermore, I suspect I never will. It’s one of the key troubles of life. We can recognize quality, we can have highly refined tastes, and at the same time have no idea why we have those tastes. Articulating those likes and desires is much harder than having them in first place.
The sliding scale is a fantasy. There’s no simple answers.
(Worm)
In a way, it’s like NP-Complete problems. If we’re given an explanation, we’ll understand it, but it’s incredibly difficult to find that explanation in the first place. Guess that’s why critics get to keep their jobs.
We read and hear many things. Somehow, our brains decide which input is truly memorable, and worth keeping verbatim, while the rest gets relegated to vague feelings. The strangest part to me is that for the most part, people agree on what quotes are important. Legendary movies are usually quoted in the same way.
Here’s looking at you, kid.
(Casablanca)
Yes, quality is subjective, but quality isn’t entirely subjective. If someone tried to hold up Plan 9 From Outer Space as a masterpiece of science fiction instead of a masterpiece of unintended comedy, we’d laugh them out of the room.
Future events such as these will affect you in the future.
(Plan 9 From Outer Space)
There must be some core functionality, that recognizes some idea as important, and it has to be almost the same from person to person. In the brain, we can’t be that different. Can we?
Harry was finding himself very disturbed by how reproducible human thoughts were when you reset people back to the same initial conditions and exposed them to the same stimuli.
(Harry Potter and the Methods of Rationality)
So what does it? What makes a quote memorable?
I want to know, because if you understand how this works, it’s a improvement on everything I can think of. It makes your writing more interesting. It makes your speeches more persuasive. Technical explanations from research papers stick better.
I am an anti-illusionist. I trick your brain into seeing what was there all along.
(Vi Hart)
Understanding this seems key to all forms of communication, and communication underlies essentially every interaction in the world. Shouldn’t I be training that meta-skill?
She was such a potent telepath that even if I could come up with a plan, she would rip it from my mind before I could get close enough to her to implement it.
We were racing apotheosis. And we were losing.
I bet this is the sales pitch people use when trying to sell the books they’ve written on persuasion. It has to work, right? I mean, it seems self-evident. Of course, what isn’t self-evident is that they’re the best person for explaining persuasion.
Where does that leave me? It is an unfortunate truth that there isn’t enough time to understand everything, or even understand most things. Eventually, you have to choose what’s worth learning and what isn’t. Or perhaps more accurately, you don’t choose. Instead, we naturally gravitate toward our interests and circle them endlessly, never quite passing the event horizon into true clarity.
“I understand why you want, and need, the universe to be simple, to be ‘just so’. But it simply isn’t. Stop thinking you know what ‘quantum’ means. Magic isn’t a miraculous healing field, it doesn’t bind living creatures to one another. Crack a book open, one that isn’t aiming to pander. The answers are complicated. We will find every explanation eventually. As for me, I will uncover the truth on my own terms. The proper way. Or, more likely, I will not.
(Ra)
Like I said, I still don’t have any answers. The closest idea I can think of is hopelessly general, but probably still correct.
- Breathe in.
- Breathe out.
- Get a rough idea of what you need to do.
- Walk there, one step at a time.
It’s fluffy, I know. But I’ve heard a variation on this idea from several sources, so it can’t be all junk. I suppose that’s what I’ll do, and at some point, if I get there, I can write my own feel-good story, and pretend to be someone who understood what he was doing all along.
This final quote doesn’t quite fit. But, after re-reading it, I liked it too much. It’s memorable to me.
“I want to calm the storm, but the war is in your eyes.
How can I shield you from the horror and the lies?When all that once held meaning is shattered, ruined, bleeding
And the whispers in the darkness tell me we won’t survive?”“All things will end in time, this coming storm won’t linger
Why should we live as if there’s nothing more?So hold me ‘neath the thunderclouds, my heart held in your hooves,
Our love will keep the monsters from our door.”“For I know tomorrow will be a better day.
Yes, I believe tomorrow can be a better day…”