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 Post subject: Re: Riddle Me This...Posted: Mon Nov 19, 2012 8:58 pm

Joined: Sun May 29, 2011 2:56 pm
Location: New York
bmenrigh wrote:
Well I think twisty puzzle enthusiasts would also be particularly well suited for this strategy (hint hint)!

This is driving me nuts. I feel like you are giving away the riddle, and we just aren't seeing it.
I'm seeing a huge "Ohh, I see! How did I ever miss that????" coming up

-Doug

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 Post subject: Re: Riddle Me This...Posted: Mon Nov 19, 2012 9:10 pm

Joined: Mon Mar 30, 2009 5:13 pm
I think it's easy to come up with some kind of permutation strategy that would give the resulting skewed probability distribution (100% correct 30% of the time), but this would only work if all of the mathematicians were able to agree upfront to cooperate and use the same strategy. That's why I want to clarify this question.

Otherwise, if there is no implicit or explicit agreement between the mathematicians to follow the same strategy or formula then I can't see how it could work. Surely there *must* be some common understanding to cooperate at some level, even if it is based on some implicit objective to maximize the overall winnings across the group, because not every individual may see it that way.

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 Post subject: Re: Riddle Me This...Posted: Mon Nov 19, 2012 9:20 pm

Joined: Wed Jan 21, 2009 12:58 pm
I've been silently following this latest riddle. Very nice indeed. Question: does the answer has anything to do with the Mathieu groups?

Skarabajo.

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 Post subject: Re: Riddle Me This...Posted: Mon Nov 19, 2012 9:22 pm

Joined: Thu Dec 31, 2009 8:54 pm
Location: Bay Area, California
KelvinS wrote:
I think it's easy to come up with some kind of permutation strategy that would give the resulting skewed probability distribution (100% correct 30% of the time), but this would only work if all of the mathematicians were able to agree upfront to cooperate and use the same strategy. That's why I want to clarify this question.

Otherwise, if there is no implicit or explicit agreement between the mathematicians to follow the same strategy or formula then I can't see how it could work. Surely there *must* be some common understanding to cooperate at some level.

In an ideal situation where all of the mathematicians were aware of the strategy then all it would take is a big grin and a wink and everyone else would immediately know to use the strategy. Actually, if you were a mathematician going onto a game show like this it would probably be very hard to talk you out of using the strategy.

In reality though, not all of the mathematicians would know the strategy. All it would take is for one to explain the strategy to everyone. This would take about 30 seconds and would not require elaborate planning and specific roles do not need to be assigned.

If the mathematicians wanted to try to hide their strategy from the audience then somebody would have to come up with the permutation to the strategy and explain what to do. That'd probably take another minute.

All it would really take is one mathematician contestant to stand up before the show in front of all of the other contestants and say "Everyone follow this strategy. I know it sounds crazy but I'm a mathematician, just trust me." It's really simple to follow. Hiding it from the audience and studio is less simple.

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 Post subject: Re: Riddle Me This...Posted: Mon Nov 19, 2012 9:28 pm

Joined: Mon Mar 30, 2009 5:13 pm
bmenrigh wrote:
In reality though, not all of the mathematicians would know the strategy. All it would take is for one to explain the strategy to everyone. This would take about 30 seconds and would not require elaborate planning and specific roles do not need to be assigned.

If the mathematicians wanted to try to hide their strategy from the audience then somebody would have to come up with the permutation to the strategy and explain what to do. That'd probably take another minute.

OK, so I would use just 5 seconds of that 30-90 seconds to tell everyone to pick the first 50 boxes. Then 100% of the group would win 50% of the time, rather than just 30% of the time. And I wouldn't care if the audience noticed the strategy, because it doesn't break any rules.

So I'm not impressed by this over-complicated puzzle.

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 Post subject: Re: Riddle Me This...Posted: Mon Nov 19, 2012 9:34 pm

Joined: Thu Dec 31, 2009 8:54 pm
Location: Bay Area, California
Skarabajo wrote:
I've been silently following this latest riddle. Very nice indeed. Question: does the answer has anything to do with the Mathieu groups?

Actually no. I'm not familiar with Mathieu groups but they look like groups of certain sizes with some interesting subgroup properties.

The solution to my riddle is more primitive than that.
Think https://en.wikipedia.org/wiki/Permutation_group and https://en.wikipedia.org/wiki/Cycle_notation

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 Post subject: Re: Riddle Me This...Posted: Mon Nov 19, 2012 11:40 pm

Joined: Thu Dec 02, 2004 12:09 pm
Location: Missouri
Here is the strategy that I'd try.

(2) Pick the case of the same number. It has a 1:100 chance of containing the same number if its random. If you get lucky you win. No need to continue.
(3) 99:100 of the time that case will contain a different number. So pick the case number that matches the number found in the first case as your next case to try.
(4) Repeat this 49 times.

The benefit I see from following this strategy is as follows. You'll only ever sample cases where you know the number inside the case is DIFFERENT then the case number. Except for maybe the very first case... and if that happens you've already won. And any other case which may hold its own number you know is a losing case so you don't want to open those anyways.

As for checking this strategy I'd need to write a program to see if I could reproduce any of Brandon's graphs. But I still think I'm missing something as I think this is the best strategy even if things are re-randomized between contestants. And if I'm correct, his "super big hint" makes no sense to me as I would think that would open oneself up to wasting chances opening cases that COULD contain their own number. However this seems to fit "the answer" he gave... at least in my mind.

Carl

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 Post subject: Re: Riddle Me This...Posted: Mon Nov 19, 2012 11:51 pm

Joined: Thu Dec 31, 2009 8:54 pm
Location: Bay Area, California
I like your strategy I'll hold off commenting while you think about it some more.
wwwmwww wrote:
[...]And if I'm correct, his "super big hint" makes no sense to me as I would think that would open oneself up to wasting chances opening cases that COULD contain their own number. However this seems to fit "the answer" he gave... at least in my mind.
Without the super big hint, if case 20 contains the number 20 then the case has its own number.

In the super big hit scenario:
"Pick 20. ((20 * 7) + 3 mod 100 == 43 (I'm ignoring for the 1-100 versus modulus 0-99 offset junk). Open case 43. If it contains the number 20 then "the case contains its own number"."

EDIT: I'll slip in one comment though. Your analysis about any other case containing its own number and therefor that's a losing case anyways is correct. That could possibly increase the odds a bit better than 50/50. How did 20 folks all win and how does that happen 30% of the time?

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 Post subject: Re: Riddle Me This...Posted: Tue Nov 20, 2012 12:07 am

Joined: Thu Dec 02, 2004 12:09 pm
Location: Missouri
bmenrigh wrote:
EDIT: I'll slip in one comment though. Your analysis about any other case containing its own number and therefor that's a losing case anyways is correct. That could possibly increase the odds a bit better than 50/50. How did 20 folks all win and how does that happen 30% of the time?
Well the way I see it is the 100 numbers have to be cut up into a finite number of loops. If the first case doesn't contain its own number and you follow this strategy then you must eventually find the case that does. You only lose when that loop is over 50 numbers long. And without doing the math my guess is that a loop over 50 numbers long only happens 70% of the time in any such randomization. The other 30% of the time ALL the loops are under 50 numbers long so regardless of which number you pick this strategy will win. The only way you'll win the other 70% of the time is if you are lucky enough to pick a number that isn't in the largest loop.

Carl

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 Post subject: Re: Riddle Me This...Posted: Tue Nov 20, 2012 12:12 am

Joined: Thu Dec 31, 2009 8:54 pm
Location: Bay Area, California
wwwmwww wrote:
[...]Well the way I see it is the 100 numbers have to be cut up into a finite number of loops. If the first case doesn't contain its own number and you follow this strategy then you must eventually find the case that does. You only lose when that loop is over 50 numbers long. And without doing the math my guess is that a loop over 50 numbers long only happens 70% of the time in any such randomization. The other 30% of the time ALL the loops are under 50 numbers long so regardless of which number you pick this strategy will win. The only way you'll win the other 70% of the time is if you are lucky enough to pick a number that isn't in the largest loop.

Carl

EXACTLY Great job Carl!

https://en.wikipedia.org/wiki/Random_permutation_statistics See specifically the "100 prisoner problem" which this riddle is a slight variation of.

Each person starts some random place and traverses that cycle. The chance of a cycle being longer than 50 is about 70%.

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 Post subject: Re: Riddle Me This...Posted: Tue Nov 20, 2012 12:30 am

Joined: Thu Dec 02, 2004 12:09 pm
Location: Missouri
bmenrigh wrote:
EXACTLY Great job Carl!
Arg!!! Does this mean I need to come up with the next riddle? Oh... I know what I can ask... but before I ask my question let me follow up on this...
bmenrigh wrote:
That could possibly increase the odds a bit better than 50/50.
So if things are re-randomized between each constant and this strategy is followed, what are the actual odds of winning? I think its a fair bit better then 50/50 but I'm not sure how much better.

Carl

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 Post subject: Re: Riddle Me This...Posted: Tue Nov 20, 2012 12:45 am

Joined: Thu Dec 31, 2009 8:54 pm
Location: Bay Area, California
wwwmwww wrote:
bmenrigh wrote:
EXACTLY Great job Carl!
Arg!!! Does this mean I need to come up with the next riddle? Oh... I know what I can ask... but before I ask my question let me follow up on this...
bmenrigh wrote:
That could possibly increase the odds a bit better than 50/50.
So if things are re-randomized between each constant and this strategy is followed, what are the actual odds of winning? I think its a fair bit better then 50/50 but I'm not sure how much better.

Carl

I was wondering the same thing. I did some Monte Carlo testing that suggest it's nearly exactly 50/50 although I haven't tested to enough trials to say anything statistically significant.

I think the factor that offsets all of the 1-cycles that are losing choices is that if you choose 51 or greater cycle then you have to traverse the whole cycle which you can't do. The longer the cycle a permutation has, the higher the chance is that you will choose a box in the long cycle rather than one of the shorter cycles.

Another way to look at it is this. Without any knowledge of the permutation, if you open half the boxes then there is a 50% chance that you find the right number. Where the number is, is totally independent of the other numbers.

When thinking about the 30% chance of everyone finding their number, the first person (with no knowledge of the permutation) has a 50/50 chance of winning. If they lose then there is a 0% chance they all win. If that person wins then there is a much greater than 30% chance that the permutation is favorable and everyone will win.

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 Post subject: Re: Riddle Me This...Posted: Tue Nov 20, 2012 1:13 am

Joined: Thu Dec 02, 2004 12:09 pm
Location: Missouri
Ok... my riddle is more of a science question. This is the very question I asked my 7th grade science teacher and you'll get bonus points if you can guess what his answer to it was. His answer wasn't the one you'd expect if you already know the answer to this question. Anyways here is the picture I drew on the chalk board.
Attachment:

Planets.png [ 5.62 KiB | Viewed 3459 times ]

You have 3 planets... call them A, B, and C. The people who live on planet B are capable of near light speed travel. Planet B is stationary in this rest frame. Planet A is moving 0.9c to the left and Plant C is moving 0.9c to the right. For the sake of this problem assume these people life long enough that the actual distances they need to travel isn't a problem. The people of Planet B build a rocket with a top speed of 0.95c and they use it to fly to plant A. Here they befriend the local population and a native volunteers to join the crew. They now all fly back to planet B all while never going over 0.95c. Here they have a ticker tape parade and the native from planet A gets famous. A year later the crew decides to visit planet C and the native from planet A comes along. As they accelerate past 0.1c to the right all the crew from planet B is just fine but I'm concerned about the now famous crew member native to planet A. What is happening to him?

(1) As he can't go faster then the speed of light away from his home planet's rest frame is he crushed against the rear of the rocket?
(2) Since he's been eating the native foods found on Planet B for a year is he just fine as enough of his mater has been replaced with mater from a new rest frame?
(3) In general is it possible to get someone safely from Planet A to Planet C... and if so how?

By the way, my 7th grade science teacher answered question (3) and never really said much about (1) or (2). To be honest I didn't like his answer at the time but now that I have a Ph.D in Physics I do see that it could actually be correct in some sense. In my case I think it was actually a few years later before I actually had this question answered for me.

Since I know there are certainly many here that know the correct answer to the question... what I'd really like to see is what do you think a 7th grade science teacher unfamiliar with relativity would guess is the best/safest way to get from Planet A to Planet C. And its certainly a guess that I view could be considered correct in the context of this problem. Its just not near as "satisfying" as knowing something about relativity.

Carl

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 Post subject: Re: Riddle Me This...Posted: Tue Nov 20, 2012 1:30 am

Joined: Thu Dec 31, 2009 8:54 pm
Location: Bay Area, California
Hmm well somebody that "knows nothing can go faster that the speed of light" but also doesn't really understand special relativity would probably say that you can't have the planet on the left and on the right both going .9c away from the center. The max would be that the absolute magnitude of their velocities must sum to less than 1c.

I won't spoil the fun of somebody else solving the math portion of your problem but I will say that from the reference frame of A:

A = 0c
B = .9c to the right
C = 0.9945c to the right

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 Post subject: Re: Riddle Me This...Posted: Tue Nov 20, 2012 1:45 am

Joined: Thu Dec 02, 2004 12:09 pm
Location: Missouri
bmenrigh wrote:
Hmm well somebody that "knows nothing can go faster that the speed of light" but also doesn't really understand special relativity would probably say that you can't have the planet on the left and on the right both going .9c away from the center. The max would be that the absolute magnitude of their velocities must sum to less than 1c.
Nope... he didn't have a problem with that part of it.
bmenrigh wrote:
I won't spoil the fun of somebody else solving the math portion of your problem but I will say that from the reference frame of A:

A = 0c
B = .9c to the right
C = 0.9945c to the right
He certainly didn't know this... or if he did, he didn't what to try and explain it to me at the time. But let's assume he did know this. And also assume the people of Planet A have a rocket with a top speed of 0.95c. How can they ever hope to catch up with Planet C? I suspect his answer would have been the same.

Hint: The black board represents the universe in this problem.

Carl

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 Post subject: Re: Riddle Me This...Posted: Tue Nov 20, 2012 2:11 am

Joined: Thu Dec 31, 2009 8:54 pm
Location: Bay Area, California
So perhaps he said that the ship can only travel .95c from where it took off? Take off from planet A, slowly catch up to B. Land. Take off from planet B, slowly catch up to C?

This seems almost like relativistic answer.

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 Post subject: Re: Riddle Me This...Posted: Tue Nov 20, 2012 11:20 am

Joined: Thu Dec 02, 2004 12:09 pm
Location: Missouri
bmenrigh wrote:
So perhaps he said that the ship can only travel .95c from where it took off? Take off from planet A, slowly catch up to B. Land. Take off from planet B, slowly catch up to C?
Nope... his answer didn't make use of Planet B at all. Granted I realize that making the statement that a ship can never go over 0.95c in its initial reference frame is pretty arbitrary. Physically I would think restrictions like this would need to be made on the ships acceleration instead but maybe you could assume the ship can only carry enough fuel to reach 0.95c. Regardless... my 7th grade science teacher's solution did get you from Planet A to Planet C whichout ever going over 0.95c relative to Planet A. However thinking about it now I don't think you'd survive the landing on Planet C.

Carl

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 Post subject: Re: Riddle Me This...Posted: Tue Nov 20, 2012 11:28 am

Joined: Thu Dec 31, 2009 8:54 pm
Location: Bay Area, California
wwwmwww wrote:
[...]Nope... his answer didn't make use of Planet B at all. Granted I realize that making the statement that a ship can never go over 0.95c in its initial reference frame is pretty arbitrary. Physically I would think restrictions like this would need to be made on the ships acceleration instead but maybe you could assume the ship can only carry enough fuel to reach 0.95c.
I was going to make this quibble in the beginning and say just about exactly the same thing which is what lead me to the A->B (land) B->C. Since the question is more about the solution your teacher provided rather than real physics it doesn't matter much.

So let me ask you a question. As a 7th grader were you satisfied with his solution? I don't think I would have been satisfied with things like "well if space is curved" or "if you leave planet A going left to exceed the speed of light you can go back in time", etc. EDIT: I can't read. You already wrote "To be honest I didn't like his answer at the time but now that I have a Ph.D in Physics I do see that it could actually be correct in some sense."

Edit 2:
Alright how about another guess as to the purported solution. Think of a car. You can drive 100mph south or 100mph north. If you start going 100mph south and slowly turn you'll end up going 100mph north. The difference is 200mph which your car can't go but that doesn't matter.

So to get somebody from A to C take off from A going LEFT until you reach 1.0c then turn your rocket in a curve until you're heading towards C at 1.0c rather than .95c (by using the speed of planet A as a boost).

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 Post subject: Re: Riddle Me This...Posted: Tue Nov 20, 2012 11:49 am

Joined: Thu Dec 02, 2004 12:09 pm
Location: Missouri
bmenrigh wrote:
Since the question is more about the solution your teacher provided rather than real physics it doesn't matter much.
Oh I wouldn't say his answer didn't fall within the realm of "real physics". I know there are real astronomers out there that believe our own universe has the property that my teacher expolited. I don't think I fall within that camp but they are out there.
bmenrigh wrote:
So let me ask you a question. As a 7th grader were you satisfied with his solution?
Nope, I wasn't satisfied at all. I felt he cheated.
bmenrigh wrote:
I don't think I would have been satisfied with things like "well if space is curved" or "if you leave planet A going left to exceed the speed of light you can go back in time", etc.
No time travel was involved but you did hit the nail on the head. I hadn't defined the boundary properties of the universe. He simply stated you take off from planet A going to the left and he had the "universe loop back on itself" so he re-entered the chalkboard from the right side. Believe me, I wasn't happy with that idea at all... but if you get right down to it I certainly can't prove that out own universe doesn't have this property.

Carl

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 Post subject: Re: Riddle Me This...Posted: Tue Nov 20, 2012 12:00 pm

Joined: Thu Dec 31, 2009 8:54 pm
Location: Bay Area, California
wwwmwww wrote:
bmenrigh wrote:
[...]"well if space is curved"[...]
No time travel was involved but you did hit the nail on the head. I hadn't defined the boundary properties of the universe. He simply stated you take off from planet A going to the left and he had the "universe loop back on itself" so he re-entered the chalkboard from the right side. Believe me, I wasn't happy with that idea at all... but if you get right down to it I certainly can't prove that out own universe doesn't have this property.
Hmm I thought of and rejected this purported solution in the very beginning as a cop-out.

Since you were doing this on a blackboard I sure hope you asked if the topology of this curved universe was more like the surface of a torus where the left and right edges of the blackboard and top and bottom meet or more like a sphere where there are no edges.

Here is another way to get somebody from planet A to C: wait. They're each rushing both away and towards each other at the same time.

I did provide an edit to my previous post that I don't think you saw so I'll replicate it here:
bmenrigh wrote:
Edit 2:
Alright how about another guess as to the purported solution. Think of a car. You can drive 100mph south or 100mph north. If you start going 100mph south and slowly turn you'll end up going 100mph north. The difference is 200mph which your car can't go but that doesn't matter.

So to get somebody from A to C take off from A going LEFT until you reach 1.0c then turn your rocket in a curve until you're heading towards C at 1.0c rather than .95c (by using the speed of planet A as a boost).

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 Post subject: Re: Riddle Me This...Posted: Tue Nov 20, 2012 12:09 pm

Joined: Mon Mar 30, 2009 5:13 pm
This is exactly like the current expanding universe model, where A and C lie on the edges relative to B at the center, but then you can also consider A or C at the center where space-time folds back on itself like the surface of an expanding balloon. Interesting that his solution seems to consider general relativity, perhaps by accident, rather than pure special relativity.

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 Post subject: Re: Riddle Me This...Posted: Tue Nov 20, 2012 12:24 pm

Joined: Thu Dec 02, 2004 12:09 pm
Location: Missouri
bmenrigh wrote:
Since you were doing this on a blackboard I sure hope you asked if the topology of this curved universe was more like the surface of a torus where the left and right edges of the blackboard and top and bottom meet or more like a sphere where there are not edges.
No... not sure I even knew what the word topology meant at the time. I more or less took it to mean the Earth is a big sphere and lets assume I put the black board on the floor. If the left of my drawing is on the west side of the board I can walk off to the left and if I walk far enough I will eventually come back up over the horizon from the east side of the board. Locally everything appears nice and flat.
bmenrigh wrote:
Here is another way to get somebody from planet A to C: wait. They're each rushing both away and towards each other at the same time.
Yes, I thought of that too. My basic response was why do you even need a rocket in that case. Planets A and C are going to collide at some point in the future anyways. So you could just wait on A and let C come to you.
bmenrigh wrote:
Edit 2:
Alright how about another guess as to the purported solution. Think of a car. You can drive 100mph south or 100mph north. If you start going 100mph south and slowly turn you'll end up going 100mph north. The difference is 200mph which your car can't go but that doesn't matter.

So to get somebody from A to C take off from A going LEFT until you reach 1.0c then turn your rocket in a curve until you're heading towards C at 1.0c rather than .95c (by using the speed of planet A as a boost).
Nope... I didn't see this. But I wouldn't have bought this solution then either. I knew getting to a speed of 1.0c was impossible even then. At the time I would have assumed someone taking off from Planet A wouldn't have been able to get moving faster then 0.05c to the left relative to Planet A. I couldn't have explained this asymmetry but I just knew it was impossible to go faster then the speed of light (or even to get to the speed of light).

A related question that was in my head at the time. Let's assume you are on Planet B with a telescope and you could see both planets A and C. I wondered if someone on Planet A would even be able to see light coming from Planet C. I had incorrectly assumed no. And my mind was telling myself that it was impossible for anyone on Planet A to even know of Planet C's existance. And in that case what if someone on Planet B were to broadcast pictures to Planet A and lets assume some of those pictures included pictures of Planet C. What would they get? These are the sorts of unanswered questions that were in my head in 7th grade. Yes I was a very odd kid. LOL!!!

Carl

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 Post subject: Re: Riddle Me This...Posted: Tue Nov 20, 2012 12:28 pm

Joined: Thu Dec 31, 2009 8:54 pm
Location: Bay Area, California
You don't actually need a curved universe to get somebody from point A to point C under some strange assumptions.

First, assume that the universe is flat, infinite, and essential uniform and random.
Second, assume that in any given region (the visible universe centered around some point) there is a finite entropy.

Now to get somebody from planet A to planet C, simply travel near the speed of light in ANY DIRECTION. Eventually you will come upon a region of space with a quantum configuration nearly exactly like the one you left except that it this new region of space the only difference is that the person on A already exists on C.

This works due to the strangeness of infinity being able to support every possible configuration of some finite region of space.

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 Post subject: Re: Riddle Me This...Posted: Tue Nov 20, 2012 12:36 pm

Joined: Thu Dec 31, 2009 8:54 pm
Location: Bay Area, California
wwwmwww wrote:
These are the sorts of unanswered questions that were in my head in 7th grade. Yes I was a very odd kid. LOL!!!

Then I think I'm in good company

When I was around 7 or so I was obsessed with magnets (I guess some things you never really grow out of!). I knew magnets stuck to iron and things with iron in them but not aluminum and many other metals. I don't remember what I was thinking at the time but one day I asked my mother what would happen if you melted iron. Would it still stick to a magnet? I don't remember the answer I got at the time.

Fast-forward 20 years and I still don't know the answer. I'm inclined to say no. My guess is that molten iron is paramagnetic but not strongly enough to actually stick to the magnet. Unless I can get a satisfactory answer some day I'm probably going to figure out a way to try it.

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 Post subject: Re: Riddle Me This...Posted: Tue Nov 20, 2012 12:40 pm

Joined: Mon Mar 30, 2009 5:13 pm
These puzzles are getting pretty deep, so here's another one to get everyone thinking:

Imagine you put some bacteria (unspecified number) in a flask at exactly 11.00am, and the population doubles every minute until the flask is full of bacteria an hour later at exactly 12.00pm. Now, 3 basic questions:

1. At what time would the flask be half full of bacteria?
2. At what time would an individual bacterium start to worry that space is becoming a bit tight?
3. Now imagine if you made a miraculous discovery and added 3 more flasks (four times the total current available volume), at what time would all 4 flasks be full of bacteria?

Finally, once you've figured these out, think about how this relates to human population growth with limited space and natural resources. Worried? You should be!

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 Post subject: Re: Riddle Me This...Posted: Tue Nov 20, 2012 12:46 pm

Joined: Thu Dec 31, 2009 8:54 pm
Location: Bay Area, California
Exponential growth is scary.

The flask was half full at 11:59 and all of the bacteria were saying "overpopulation? What are you talking about there is plenty of space!". At 12:00 they're worried about space.

4 flasks would be full at 12:02

The analogy to the Earths population is pretty shaky though.

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 Post subject: Re: Riddle Me This...Posted: Tue Nov 20, 2012 12:54 pm

Joined: Mon Mar 30, 2009 5:13 pm
bmenrigh wrote:
Exponential growth is scary.

The flask was half full at 11:59 and all of the bacteria were saying "overpopulation? What are you talking about there is plenty of space!". At 12:00 they're worried about space.

4 flasks would be full at 12:02

The analogy to the Earths population is pretty shaky though.

Correct, and true: as with bacteria, the population starts to die and growth will slow before the flask is actually full, but having done exactly this kind of experiment with bacteria in the lab, I can tell you that the smell of death at that stage is extremely unpleasant!

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 Post subject: Re: Riddle Me This...Posted: Tue Nov 20, 2012 1:38 pm

Joined: Thu Dec 02, 2004 12:09 pm
Location: Missouri
bmenrigh wrote:
This works due to the strangeness of infinity being able to support every possible configuration of some finite region of space.
Yes... but this assumes an infinite universe and I don't think I would have been very happy with this answer in 7th grade either. Personally I think the universe is finite and flat... but in that picture I still have questions. What is the volume outside the bouble of our universe like? I think of empty space as nothing... but it is actually something. At the edge of this bouble... if it exists there must be something very interesting going on. Even if you are near the edge of this bouble I would assume you'd never be able to stick anything though the bouble as I believe it would have to be moving away from you at the speed of light too. Still I'm very curious... what is on the other side?
bmenrigh wrote:
Fast-forward 20 years and I still don't know the answer. I'm inclined to say no. My guess is that molten iron is paramagnetic but not strongly enough to actually stick to the magnet. Unless I can get a satisfactory answer some day I'm probably going to figure out a way to try it.
Oh I loved magnets too. Actually I think magnets may have been the very first thing that I ever collected... before dice and twisty puzzles. This was back before the rubiks cube even came out. I was always looking for bigger and more powerful magnets. And I have actually seen the answer to your question before. No molten iron will not stick to a magnet. I think even the magnetic properties of solid iron fall off rather quickly as one approaches the melting point. I can't now remember where I came across these details but I know I've read on this topic before.

Are you familiar with electrets? In high school one year my science project for the high school science fair was about electrets. It did well enough that I even ended up getting second place in Physics at the state level science fair. I was making them out of carnauba wax and using a muffen pan to hold them while they cooled. The pan itself served as one of the electrodes that held the potential across them while they solidified. I had a very fun time with that project. The highlight I remember was just finding a place that would sell me carnauba wax. Every place I looked only sold the stuff by the drum full and it was hundreds of dollars just for one drum which was far far more then I needed. I eventually found a place that offered to send me their free sample size. It was a gallon paint can size full of carnauba wax. It was perfect... and very fun stuff to play with. It was a challenge even just getting the stuff out of the can as its so hard. I ended up using a hammer and chisel to pound out flakes I could then melt in the muffin pan. Oh those were the days...

Carl

P.S. Jump forward 20 years and I see those doing what I was doing have now found it much easier to find sources of carnauba wax.
http://rimstar.org/materials/electrets/rosinbag.htm

P.S. I don't think I've seen that paint can in several decades but I know I only made a small dent in the amount of carnauba wax I had available. If I ever come across it again I'd be highly tempted to make a carnauba wax 3x3x3. I bet that has never been done before.

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 Post subject: Re: Riddle Me This...Posted: Wed Nov 21, 2012 3:05 am

Joined: Thu Dec 21, 2006 5:32 pm
Location: Bay Area, CA
It seems we have diverged from riddles to math/physics teasers. Fun, but getting off topic and perhaps accessible to fewer members. Anyone want to lead us back on course?

Dave

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 Post subject: Re: Riddle Me This...Posted: Wed Nov 21, 2012 3:53 am

Joined: Sat Jan 16, 2010 11:48 am
Location: In Front Of My Teraminx (saying WTF?)
Yes:

1) A man walks 10 miles south, then walks 10 miles east and then walks 10 miles north. Now he is back in his starting point. Where is he ?

2) A man walks 10 miles north, then 10 miles east, then 10 miles south, then 10 miles west. He is NOT in his starting position. Where is he ?

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Last edited by RubixFreakGreg on Wed Nov 21, 2012 4:23 am, edited 1 time in total.

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 Post subject: Re: Riddle Me This...Posted: Wed Nov 21, 2012 4:01 am

Joined: Mon Mar 30, 2009 5:13 pm
1. North Pole, or on a huge platform that is slowly moving west
2. Anywhere on earth (or any other magnetic planet) except 5 miles south of the equator

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 Post subject: Re: Riddle Me This...Posted: Wed Nov 21, 2012 4:23 am

Joined: Sat Jan 16, 2010 11:48 am
Location: In Front Of My Teraminx (saying WTF?)
KelvinS wrote:
1. North Pole, or on a huge platform that is slowly moving west
2. Anywhere on earth (or any other magnetic planet) except 5 miles south of the equator

1) why a huge platform ? just the north pole, but you are correct.
2) Correct !

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 Post subject: Re: Riddle Me This...Posted: Wed Nov 21, 2012 5:04 am

Joined: Mon Mar 30, 2009 5:13 pm
RubixFreakGreg wrote:
why a huge platform ? just the north pole, but you are correct.

It was an alternative answer, because you said there were two possible solutions (until you changed it after my post).

So next one:

What goes buzz buzz clack clack tinkle pop bang?

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 Post subject: Re: Riddle Me This...Posted: Wed Nov 21, 2012 5:58 am

Joined: Thu Apr 19, 2012 6:33 am
Location: Belgium
DLitwin wrote:
It seems we have diverged from riddles to math/physics teasers. Fun, but getting off topic and perhaps accessible to fewer members. Anyone want to lead us back on course?

Dave

Just recieved a nice mathematical problem, maybe we can start a new topic for these puzzles?

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 Post subject: Re: Riddle Me This...Posted: Wed Nov 21, 2012 6:02 am

Joined: Thu Apr 19, 2012 6:33 am
Location: Belgium
KelvinS wrote:
What goes buzz buzz clack clack tinkle pop bang?

Something to do with drinks?

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 Post subject: Re: Riddle Me This...Posted: Wed Nov 21, 2012 6:22 am

Joined: Mon Mar 30, 2009 5:13 pm
mixer wrote:
KelvinS wrote:
What goes buzz buzz clack clack tinkle pop bang?

Something to do with drinks?

I honestly have no idea. My laptop has been making this noise, so I just wanted to check if it was normal.

OK, somebody else can post a new riddle.

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 Post subject: Re: Riddle Me This...Posted: Wed Nov 21, 2012 9:16 am

Joined: Sun Apr 16, 2000 3:17 pm
Location: Hong Kong
And here I thought it was a child in the bathroom.....

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 Post subject: Re: Riddle Me This...Posted: Wed Nov 21, 2012 10:42 am

Joined: Mon Jan 05, 2009 9:05 pm
What is it that was given to you, belongs only to you, and yet your friends use it more than you do?

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 Post subject: Re: Riddle Me This...Posted: Wed Nov 21, 2012 11:10 am

Joined: Sun Mar 15, 2009 12:00 am
Location: Jarrow, England
Well it can't be my name, because that is Lawrence, but all my friends call me Gus

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 Post subject: Re: Riddle Me This...Posted: Wed Nov 21, 2012 1:14 pm

Joined: Fri Feb 18, 2000 8:50 am
Location: chicago, IL area U.S.A
This is one of my favorites.

What is brown and sticky?

-d

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 Post subject: Re: Riddle Me This...Posted: Wed Nov 21, 2012 1:20 pm

Joined: Mon Aug 18, 2008 10:16 pm
Location: Somewhere Else
A stick!

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 Post subject: Re: Riddle Me This...Posted: Wed Nov 21, 2012 1:22 pm

Joined: Fri Mar 18, 2011 10:41 am
Location: Passau, Germany
Hi Darryl!

darryl wrote:
What is brown and sticky?

The answer is generally considered to be: a stick.
There are plenty of other funny answers that can be found in the net.

Let me ask a new version of an earlier question in this thread:

You can see me, but you cannot touch me. I am generally considered to
be beautiful. But if you break me, I vanish.

Good luck,
Martin

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 Post subject: Re: Riddle Me This...Posted: Wed Nov 21, 2012 1:26 pm

Joined: Sun Mar 15, 2009 12:00 am
Location: Jarrow, England
A soap bubble?

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 Post subject: Re: Riddle Me This...Posted: Wed Nov 21, 2012 1:30 pm

Joined: Fri Mar 18, 2011 10:41 am
Location: Passau, Germany
Gus wrote:
A soap bubble?

And possibly you can touch a soap bubble
if you are careful. At least you can get wet.

Try again ...

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 Post subject: Re: Riddle Me This...Posted: Wed Nov 21, 2012 2:19 pm

Joined: Thu Apr 19, 2012 6:33 am
Location: Belgium
A mirror?

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 Post subject: Re: Riddle Me This...Posted: Wed Nov 21, 2012 2:37 pm

Joined: Fri Mar 18, 2011 10:41 am
Location: Passau, Germany
mixer wrote:
A mirror?

Not quite. I can touch my mirror. And if I break it, it does not
vanish, but produces nasty bits of broken glass.

Hint: I had assumed the answer would be easy for twisty puzzle fans.

Last edited by Martin on Wed Nov 21, 2012 2:53 pm, edited 1 time in total.

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 Post subject: Re: Riddle Me This...Posted: Wed Nov 21, 2012 2:39 pm

Joined: Thu Dec 02, 2004 12:09 pm
Location: Missouri
Symmetry?

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 Post subject: Re: Riddle Me This...Posted: Wed Nov 21, 2012 2:52 pm

Joined: Fri Mar 18, 2011 10:41 am
Location: Passau, Germany
wwwmwww wrote:
Symmetry?

Yes! Excellent!

Now it is your turn ...

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 Post subject: Re: Riddle Me This...Posted: Wed Nov 21, 2012 3:46 pm

Joined: Thu Dec 02, 2004 12:09 pm
Location: Missouri
Martin wrote:
Now it is your turn ...
Arg... I'm horible at these. Last time I took things off topic. I'll try do do better this time.

I'm known to be a companion, and an unusual one. I have a much more famous bigger brother, but no one seems to ever call him by name. His followers are all considered crazy, but you have at least visited him. You've so far left me alone... but that doesn't stop me from dancing with you. What is my name?

Carl

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 Post subject: Re: Riddle Me This...Posted: Thu Nov 22, 2012 2:42 am

Joined: Thu Apr 19, 2012 6:33 am
Location: Belgium
The Moon ?

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