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Topic: BIRTHDAY TWINS (Read 24062 times) |
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Icarus
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Re: BIRTHDAY TWINS
« Reply #25 on: Oct 13th, 2005, 2:58pm » |
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on Oct 12th, 2005, 8:59pm, The Puzzler wrote:If we are almost there will you please take pity on us who go nuts when they can't figure out something and tell us the answer. My hit on the head for me saying, "Duh" won't bother me as much as not knowing.  |
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I can give you a big hint in how to find the answer:
ACTUALLY READ THE PREVIOUS POSTS! It's right there in gray and white.
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y0ung_j1n
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Re: BIRTHDAY TWINS
« Reply #26 on: Aug 1st, 2006, 11:55pm » |
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sheila DOB: 12/31 11:59:59 PM
he-man DOB: 1/1 12:00:00 AM
after he-man celebrates his birthday, 364 or 365 days later sheila, the older one, celebrates hers, during the same year no?
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towr
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Re: BIRTHDAY TWINS
« Reply #27 on: Aug 2nd, 2006, 1:41am » |
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on Aug 1st, 2006, 11:55pm, y0ung_j1n wrote:| after he-man celebrates his birthday, 364 or 365 days later sheila, the older one, celebrates hers, during the same year no? |
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Yes, but 364 or 365 days aren't 2.
The riddle states she celebrates her birthday two days later, at least once in their lifetime.
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y0ung_j1n
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Re: BIRTHDAY TWINS
« Reply #28 on: Aug 2nd, 2006, 10:53pm » |
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oh snaps im answering the bonus haha. 
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casual_kumar
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Re: BIRTHDAY TWINS
« Reply #29 on: Aug 18th, 2006, 2:45am » |
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on Feb 2nd, 2005, 11:26am, THUDandBLUNDER wrote:
IIRC, it is the twin who experiences acceleration/deceleration that ages less. |
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According to Special Theory of Relativity, this is a Paradox. Both the twins will see the other twin as travelling and hence each will see the other as lived less.
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Grimbal
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Re: BIRTHDAY TWINS
« Reply #30 on: Aug 18th, 2006, 4:39am » |
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It is not a paradox. Each will see the other younger than himself, but only as long as they speed away from each other. For each of them, the point in spacetime where the brother reaches their own present age is in the future. But as soon as one of them stops and accelerates towards his brother, the change in speed will change his referential and the same point will be projected in the past. That means that if one brother stops and then accelerates enough to reach his brother, he will find him older on arrival.
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D
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Re: BIRTHDAY TWINS
« Reply #31 on: Feb 16th, 2007, 11:07pm » |
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The max number of days in a year would of course would be 365.
First it would have to be a leap year.
Second, Sheila would be born on dec 31,
he-man on jan 1. So He-man will celebrate first on Jan 1, Sheila 365 days later on dec 31. Thus the elder celebrates after the younger. 
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D
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Re: BIRTHDAY TWINS
« Reply #32 on: Feb 16th, 2007, 11:43pm » |
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Since they were born in a short time apart, the time zone births can be at most 1 hour. The days do not matter.
First, Sheila would be born on lets say Jan 3 at 12.01 am. He-man would be born on the other side on Jan 2 11.01 pm ( One day gained). Supposing the birth took place near the time line.
Then on any given year, they have to celebrate their birthdays in time zones 24 hours apart. He-man celebrating in the earlier one. (another day gained)
Then, He-man would be able to celebrate the birthday 2 days before Sheila.
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rmsgrey
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Re: BIRTHDAY TWINS
« Reply #33 on: Feb 17th, 2007, 5:58pm » |
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on Feb 16th, 2007, 11:43pm, D wrote:Since they were born in a short time apart, the time zone births can be at most 1 hour. The days do not matter.
First, Sheila would be born on lets say Jan 3 at 12.01 am. He-man would be born on the other side on Jan 2 11.01 pm ( One day gained). Supposing the birth took place near the time line.
Then on any given year, they have to celebrate their birthdays in time zones 24 hours apart. He-man celebrating in the earlier one. (another day gained)
Then, He-man would be able to celebrate the birthday 2 days before Sheila. |
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So what happens if they're Pisces instead?
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Random Lack of Squiggily Lines
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Re: BIRTHDAY TWINS
« Reply #34 on: Mar 10th, 2007, 10:06pm » |
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if 1 of them was orn on the 27th, and the other on the 28th, on a leap year the younger 1 would be selebrating his birthday 4 years after the older 1...
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I have ~50 posts to hack a "R" into a "D". Which one?
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star
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Re: BIRTHDAY TWINS
« Reply #35 on: Mar 20th, 2007, 5:02pm » |
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ooooooooooooooooooooooo
it took me forever to get this one
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| « Last Edit: Mar 20th, 2007, 5:03pm by star » |
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balanagireddy.tcs
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Re: BIRTHDAY TWINS
« Reply #36 on: Mar 22nd, 2007, 4:17am » |
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Dude..grimbal..what are you saying...?
Use your BRAIN. How can twins born from two different places...Twins are born for the same lady...
Dont give solutions for the sake of stars...Use what god has given you..:)
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alien2
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Re: BIRTHDAY TWINS
« Reply #37 on: Mar 22nd, 2007, 5:55am » |
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Quote:| Sheila and He-Man are twins; Sheila is the OLDER twin. Assume they were born immediately after each other, an infinitesimally small - but nonzero - amount of time apart. During one year in the course of their lives, Sheila celebrates her birthday two days AFTER He-Man. How is this possible? |
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Alien, because of the experiment on female brain, abducted Sheila. His flaying saucer has time travel capabilities, so after the lobotomy, alien punched in the wrong day, that is, two days into future.
Or Sheila is a working girl. So Sheila celebrated her birthday two days after him because she was too busy. Her boyfriend cares about her, even though she rarely sees him because of her career.
Or He-Man takes his sword, and makes Sheila to celebrate her birthday two days after him, because he always wanted to be the older twin.
Or Sheila is a moron, not He-Man, so she thinks that two seconds are two days, regarding their birth.
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| « Last Edit: Mar 22nd, 2007, 5:57am by alien2 » |
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rmsgrey
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Re: BIRTHDAY TWINS
« Reply #38 on: Mar 22nd, 2007, 9:57am » |
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on Mar 22nd, 2007, 4:17am, balanagireddy.tcs wrote:Dude..grimbal..what are you saying...?
Use your BRAIN. How can twins born from two different places...Twins are born for the same lady...
Dont give solutions for the sake of stars...Use what god has given you..:) |
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Very few people are born at in exactly the same place at exactly the same time. It takes less than a second to move between time zones...
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Icarus
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Re: BIRTHDAY TWINS
« Reply #39 on: Mar 22nd, 2007, 4:49pm » |
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Rmsgrey - she was referring to Grimbal's remarks about the "Twin Paradox", not the actual puzzle.
on Mar 22nd, 2007, 4:17am, balanagireddy.tcs wrote:Dude..grimbal..what are you saying...?
Use your BRAIN. How can twins born from two different places...Twins are born for the same lady...
Dont give solutions for the sake of stars...Use what god has given you..:) |
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It's a bad mistake to think Grimbal posts anything just for more stars (besides which, he can't get any more than he already has - uberpuzzler is the top ranking).
The "Twin Paradox" arises from a misunderstanding of Einstein's Special Theory of Relativity. The idea is this: two twins get in rocketships and accelerate to near the speed of light, then travel at constant speed away from each other. According to STR, since their speed is now constant, each of their viewpoints are equally valid. From twin A's viewpoint, he and his rocket are still, while B is traveling away at nearly the speed of light. Because of time-dilation (a prediction of STR), he sees B as hardly aging, so he himself is getting older, while B is barely doing the same. Ergo, he is, in his point of view, now older than B.
The problem is, B has exactly the same view of A. So how can A be older than B and B older than A?
The answer is, this can be because they are moving relative to each other, so their division of Spacetime into space and time differs. To illustrate, think of your monitor screen as a two-dimensional space time, with one direction being space, and the other perpendicular direction being time. But the question is, which direction is space, and which is time. To A, time is  and space is  . To B, time is  and space is  . Because of this disagreement, A can the point where he was his brother's "current" age as being in the past, while B sees that same point (when A reaches B's current age) as being in the future.
The reply of the "Paradox" is then "What happens if one of the twins turns his ship around and accelerates even faster, so that he eventually catches up to and passes his twin. Then they can look out the window at each other. Which will see an older version?" Grimbal's remark addresses this idea. By changing direction and speed, one of the twins changes how he sees spacetime divided into space & time. What was once a future event is now a past event, just like his brother sees it, and some past events become future events (though only too far away for him to have been aware of them as past events before they made the switch). STR does not say that his point of view and his brother's are equivalent while he is accelerating. So his brother has no balancing switch. As a result, when they overtake, each is now in agreement as to which is older. The "Twin Paradox" is called this because it violates common assumptions we make - but those assumptions are not always true. It is not a real paradox.
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JiNbOtAk
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Re: BIRTHDAY TWINS
« Reply #40 on: Mar 22nd, 2007, 5:41pm » |
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on Mar 22nd, 2007, 4:49pm, Icarus wrote:
Ergo, he is, in his point of view, now older than B.
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I know it would be something I won't understand when Icarus starts to use the word Ergo.. :P
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| « Last Edit: Mar 22nd, 2007, 9:14pm by JiNbOtAk » |
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Icarus
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Re: BIRTHDAY TWINS
« Reply #41 on: Mar 22nd, 2007, 6:17pm » |
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Hey, I am a mathematician!
That means I have to have lots of ways to say "what I just said implies what I am about to say. Trust me, it really does! Would I lie to you?"
"So", "therefore", "hence", "thus", "ergo", "whereby", "it follows that", "and", ...
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"Pi goes on and on and on ...
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Whiskey Tango Foxtrot
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Re: BIRTHDAY TWINS
« Reply #42 on: Mar 22nd, 2007, 6:59pm » |
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That was a very thorough explanation, Icarus. I've seen the "paradox" many, many times and have explained it to others as well but I must say that one rarely explains it so transparently, especially without using any diagrams. Well done.
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Grimbal
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Re: BIRTHDAY TWINS
« Reply #43 on: Mar 23rd, 2007, 2:09am » |
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on Mar 22nd, 2007, 4:49pm, Icarus wrote:| It's a bad mistake to think Grimbal posts anything just for more stars (besides which, he can't get any more than he already has - uberpuzzler is the top ranking). |
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WHAAAT?  There is no higher rank? Damn!  All this time I thought I was working towards something, that kept me going.  I guess I better restart with another nick name. 
PS: 
Regarding Icarus's explanation, there is at least one mistake. Space moves the other way round.
Let's take a clock dial to describe directions.
From A's point of view, A's time arrow is at 12 o'clock and his space arrow is at 3 o'clock. If B moves relatively to A and B's time arrow is at 1 o'clock, then B's space arrow is at 2 o'clock.
You can convert from A's point of view to B's point of view by squeezing your clock at 1:30 and 7:30 and pulling at 4:30 and 10:30. In effect, the dial flattens towards a diagonal. In the process B's time arrow moves to the vertical, 12 o'clock for B, and his time arrow moves to the horizontal, 3 o'clock for B. Also, A's time arrow moves to B's 11 o'clock and A's space arrow moves to B's 4 o'clock.
In the above description the size of the arrow is another issue. When I say B's time arrow is at 1 o'clock, it is only the direction. It actually moves along a hyperbola with asymptotes at x=+/-y.
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| « Last Edit: Mar 25th, 2007, 6:45am by Grimbal » |
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towr
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Re: BIRTHDAY TWINS
« Reply #44 on: Mar 23rd, 2007, 2:22am » |
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on Mar 22nd, 2007, 4:49pm, Icarus wrote:| The reply of the "Paradox" is then "What happens if one of the twins turns his ship around and accelerates even faster, so that he eventually catches up to and passes his twin. Then they can look out the window at each other. Which will see an older version?" Grimbal's remark addresses this idea. By changing direction and speed, one of the twins changes how he sees spacetime divided into space & time. What was once a future event is now a past event, just like his brother sees it, and some past events become future events (though only too far away for him to have been aware of them as past events before they made the switch). STR does not say that his point of view and his brother's are equivalent while he is accelerating. So his brother has no balancing switch. As a result, when they overtake, each is now in agreement as to which is older. The "Twin Paradox" is called this because it violates common assumptions we make - but those assumptions are not always true. It is not a real paradox. |
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What if both brothers mirror each other actions and both turn around at the same time (and in the same way) to meet?
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Grimbal
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Re: BIRTHDAY TWINS
« Reply #45 on: Mar 23rd, 2007, 3:14am » |
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Then both will experience an acceleration, both will change point of view in a way that the point in space-time they considered as the place where the other is in the present becomes a point where the other was in the past, while a point where the other will be in the future becomes the present. Each will suddenly see the other much older, not because any sudden aging of the other, but because the label of what is "the present" for A in B's time line moved to the future.
Both will have the same age when they meet. From any point of view, they spent as much time at each speed, so they aged the same overall.
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Icarus
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Re: BIRTHDAY TWINS
« Reply #46 on: Mar 23rd, 2007, 7:30pm » |
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on Mar 22nd, 2007, 6:59pm, Whiskey Tango Foxtrot wrote:| That was a very thorough explanation, Icarus. I've seen the "paradox" many, many times and have explained it to others as well but I must say that one rarely explains it so transparently, especially without using any diagrams. Well done. |
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Thank you, but it was actually far from thorough, and not even entirely accurate, as someone just had to point out! For the lack of thoroughness, note that I didn't even say which twin would be the elder when they passed, much less actually explain why.
The lucid parts came simply because I was expanding on Grimbal's already lucid, if short, earlier post.
on Mar 23rd, 2007, 2:09am, Grimbal wrote:| Regarding Icarus's explanation, there is one mistake. |
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Only ONE! Wow, I'm doing better than I thought! And I obviously left out a word by mistake here:
Quote:| A can the point where he was his brother's "current" age as being in the past |
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Ergo, all that other stuff you are going on about must have been okay in my post after all!
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deestore
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Re: BIRTHDAY TWINS
« Reply #47 on: Jun 10th, 2007, 2:08am » |
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I think this is a two factor problem. I think He-man was born February 29 just before midnight and Sheila just after midnight, on March 1st. As the years go by, Shiela turns another year older every March 1st, but He-man only turns a year older every four years (since there's only a 29th of February every four years). Thus, Shiela is the OLDER twin. Ok, so now I've resolved why Shiela is older.
Then, consider it to be another year that has 29 days in February. He-man celebrates his birthday on the 29th. Then, Sheila would celebrate hers on March 1st. But that's only one day later. However, if we put He-man on one side of the dateline and Sheila on the other, we can actually make the celebrations two days apart. He-man would celebrate on the 29th. Sheila would celebrate two day's later in a location where it is still March 1st for her, but March 2nd for He-man.
To answer the bonus question: I haven't researched time changes over the dateline, but I think it can be almost three days between celebrations, if He-man celebrates his birthday at the stroke of midnight on the 29th where he's at and Sheila celebrates at the last possible second on the 1st where she's at  .
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ThudnBlunder
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Re: BIRTHDAY TWINS
« Reply #48 on: Jun 10th, 2007, 5:11am » |
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on Mar 22nd, 2007, 4:49pm, Icarus wrote:| It is not a real paradox. |
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What is a real paradox?
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Grimbal
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Re: BIRTHDAY TWINS
« Reply #49 on: Jun 10th, 2007, 11:00am » |
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on Jun 10th, 2007, 5:11am, ThudanBlunder wrote:
Ah...
What paradox is not real?
OK, I should have said: "I can explain that".
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