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  3. Imaginary numbers... (last one, I promise)

Imaginary numbers... (last one, I promise)

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  • D Offline
    D Offline
    DerekT P
    wrote on last edited by
    #1

    ... for example: a woman's age, a car mechanic's repair estimate, the president's weight. (That last example might get me in trouble, but hey, seems I'm already in trouble here). Thank you and good night.

    Telegraph marker posts ... nothing to do with IT Phasmid email discussion group ... also nothing to do with IT Beekeeping and honey site ... still nothing to do with IT

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    • D DerekT P

      ... for example: a woman's age, a car mechanic's repair estimate, the president's weight. (That last example might get me in trouble, but hey, seems I'm already in trouble here). Thank you and good night.

      Telegraph marker posts ... nothing to do with IT Phasmid email discussion group ... also nothing to do with IT Beekeeping and honey site ... still nothing to do with IT

      A Offline
      A Offline
      Amarnath S
      wrote on last edited by
      #2

      One of my math professors had said that "all numbers are imaginary". For example, I can show you two oranges, or two cats, but I cannot show just "two". So, all the numbers we deal with, are in our head, mind. We write it, of course, as 2, but that is just a representation of "two" in my written language. The same 2 is written as ೨ in my language Kannada, and as २ in Devanagari script. But none of them are the concept called "two"; the concept called "two" is imagined in my mind, it is imaginary. This was the logic of my professor. Stated otherwise, I cannot see, hear, touch, smell or taste "two" or "three". None of the numbers is tangible in that sense. The concept of "imaginary number i" takes that imagination abstraction to the next level.

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      • A Amarnath S

        One of my math professors had said that "all numbers are imaginary". For example, I can show you two oranges, or two cats, but I cannot show just "two". So, all the numbers we deal with, are in our head, mind. We write it, of course, as 2, but that is just a representation of "two" in my written language. The same 2 is written as ೨ in my language Kannada, and as २ in Devanagari script. But none of them are the concept called "two"; the concept called "two" is imagined in my mind, it is imaginary. This was the logic of my professor. Stated otherwise, I cannot see, hear, touch, smell or taste "two" or "three". None of the numbers is tangible in that sense. The concept of "imaginary number i" takes that imagination abstraction to the next level.

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        C Offline
        CPallini
        wrote on last edited by
        #3

        Your argument is unnecessarily complex.

        "In testa che avete, Signor di Ceprano?" -- Rigoletto

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        • C CPallini

          Your argument is unnecessarily complex.

          "In testa che avete, Signor di Ceprano?" -- Rigoletto

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          K Offline
          Kenneth Haugland
          wrote on last edited by
          #4

          Mathematicians are special. They cannot calculate sqrt(-1) and instead of giving up math, they simply state that we have discovered a new number. I swear, you cannot win against these people...

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          • K Kenneth Haugland

            Mathematicians are special. They cannot calculate sqrt(-1) and instead of giving up math, they simply state that we have discovered a new number. I swear, you cannot win against these people...

            C Offline
            C Offline
            CPallini
            wrote on last edited by
            #5

            Physicists do the same all the time.

            "In testa che avete, Signor di Ceprano?" -- Rigoletto

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            • C CPallini

              Physicists do the same all the time.

              "In testa che avete, Signor di Ceprano?" -- Rigoletto

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              D Offline
              Daniel Pfeffer
              wrote on last edited by
              #6

              CPallini wrote:

              Physicists do the same all the time.

              The difference being that they invent a new type of "energy" (potential, gravitational, electric, chemical, heat, ...)

              Freedom is the freedom to say that two plus two make four. If that is granted, all else follows. -- 6079 Smith W.

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              • D Daniel Pfeffer

                CPallini wrote:

                Physicists do the same all the time.

                The difference being that they invent a new type of "energy" (potential, gravitational, electric, chemical, heat, ...)

                Freedom is the freedom to say that two plus two make four. If that is granted, all else follows. -- 6079 Smith W.

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                C Offline
                CPallini
                wrote on last edited by
                #7

                Also spin, anti-matter and so on.

                "In testa che avete, Signor di Ceprano?" -- Rigoletto

                1 Reply Last reply
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                • D Daniel Pfeffer

                  CPallini wrote:

                  Physicists do the same all the time.

                  The difference being that they invent a new type of "energy" (potential, gravitational, electric, chemical, heat, ...)

                  Freedom is the freedom to say that two plus two make four. If that is granted, all else follows. -- 6079 Smith W.

                  K Offline
                  K Offline
                  Kenneth Haugland
                  wrote on last edited by
                  #8

                  Dark energy... What a solution :laugh: There must be some anti money job I have...

                  C 1 Reply Last reply
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                  • K Kenneth Haugland

                    Mathematicians are special. They cannot calculate sqrt(-1) and instead of giving up math, they simply state that we have discovered a new number. I swear, you cannot win against these people...

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                    O Offline
                    obermd
                    wrote on last edited by
                    #9

                    We can thank Kurt Goedel for this. He proved that in any formal logic system there are questions that can be asked but not answered in that system.

                    K 1 Reply Last reply
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                    • K Kenneth Haugland

                      Dark energy... What a solution :laugh: There must be some anti money job I have...

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                      C Offline
                      CPallini
                      wrote on last edited by
                      #10

                      Bit coins, my dear.

                      "In testa che avete, Signor di Ceprano?" -- Rigoletto

                      1 Reply Last reply
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                      • D DerekT P

                        ... for example: a woman's age, a car mechanic's repair estimate, the president's weight. (That last example might get me in trouble, but hey, seems I'm already in trouble here). Thank you and good night.

                        Telegraph marker posts ... nothing to do with IT Phasmid email discussion group ... also nothing to do with IT Beekeeping and honey site ... still nothing to do with IT

                        0 Offline
                        0 Offline
                        0x01AA
                        wrote on last edited by
                        #11

                        See this from Arpil 1. 2011: April Fools 2011: Complex Numbers in Math Class - YouTube[^] ;P :-D

                        1 Reply Last reply
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                        • K Kenneth Haugland

                          Mathematicians are special. They cannot calculate sqrt(-1) and instead of giving up math, they simply state that we have discovered a new number. I swear, you cannot win against these people...

                          J Offline
                          J Offline
                          Jon McKee
                          wrote on last edited by
                          #12

                          I'm slightly leaning into your statement, but to be fair to mathematicians, they can calculate sqrt(-1). It's sqrt(-1). It's a misunderstanding of what an imaginary number is to assume that it can be further simplified. sqrt(-1) is a 90 degree counter-clockwise rotation into the "imaginary" plane from 1 (which is a rotational plane, not a cartesian plane). That's why if you rotate it again (i.e. 1 * i * i) you arrive at -1. And if you rotate twice again you end up back at 1. They can be very useful for doing rotational math in a standard cartesian plane, for example, and avoid doing coordinate-system translations. This is a good article [^] I read awhile ago on the topic. I know in school my teachers never really explained them beyond "they just pop up so you need to know the rules", so I never developed any intuition on what they meant. A quote from the article, attributed to Carl Gauss:

                          If +1, -1, √-1 had not been called a positive, negative, imaginary (or even impossible) unit, but rather a direct, inverse, lateral unit, then there could hardly have been any talk of such obscurity.

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                          • O obermd

                            We can thank Kurt Goedel for this. He proved that in any formal logic system there are questions that can be asked but not answered in that system.

                            K Offline
                            K Offline
                            Kenneth Haugland
                            wrote on last edited by
                            #13

                            Well, you can, but then it has to be inconsistent...

                            1 Reply Last reply
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                            • J Jon McKee

                              I'm slightly leaning into your statement, but to be fair to mathematicians, they can calculate sqrt(-1). It's sqrt(-1). It's a misunderstanding of what an imaginary number is to assume that it can be further simplified. sqrt(-1) is a 90 degree counter-clockwise rotation into the "imaginary" plane from 1 (which is a rotational plane, not a cartesian plane). That's why if you rotate it again (i.e. 1 * i * i) you arrive at -1. And if you rotate twice again you end up back at 1. They can be very useful for doing rotational math in a standard cartesian plane, for example, and avoid doing coordinate-system translations. This is a good article [^] I read awhile ago on the topic. I know in school my teachers never really explained them beyond "they just pop up so you need to know the rules", so I never developed any intuition on what they meant. A quote from the article, attributed to Carl Gauss:

                              If +1, -1, √-1 had not been called a positive, negative, imaginary (or even impossible) unit, but rather a direct, inverse, lateral unit, then there could hardly have been any talk of such obscurity.

                              0 Offline
                              0 Offline
                              0x01AA
                              wrote on last edited by
                              #14

                              Thank you very much for that. Really cool one :thumbsup:

                              1 Reply Last reply
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                              • J Jon McKee

                                I'm slightly leaning into your statement, but to be fair to mathematicians, they can calculate sqrt(-1). It's sqrt(-1). It's a misunderstanding of what an imaginary number is to assume that it can be further simplified. sqrt(-1) is a 90 degree counter-clockwise rotation into the "imaginary" plane from 1 (which is a rotational plane, not a cartesian plane). That's why if you rotate it again (i.e. 1 * i * i) you arrive at -1. And if you rotate twice again you end up back at 1. They can be very useful for doing rotational math in a standard cartesian plane, for example, and avoid doing coordinate-system translations. This is a good article [^] I read awhile ago on the topic. I know in school my teachers never really explained them beyond "they just pop up so you need to know the rules", so I never developed any intuition on what they meant. A quote from the article, attributed to Carl Gauss:

                                If +1, -1, √-1 had not been called a positive, negative, imaginary (or even impossible) unit, but rather a direct, inverse, lateral unit, then there could hardly have been any talk of such obscurity.

                                K Offline
                                K Offline
                                Kenneth Haugland
                                wrote on last edited by
                                #15

                                I can further the development: see (-1)^(1/4) :-\ Imaginary numbers are actually from Italy. Solving the quintic, they came up, and everyone said they weren't real, but Cardano showed that you could actually plug in the answers and get zero out, so... They did give answers, but not a real solution that you could use in this world.

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                                • J Jon McKee

                                  I'm slightly leaning into your statement, but to be fair to mathematicians, they can calculate sqrt(-1). It's sqrt(-1). It's a misunderstanding of what an imaginary number is to assume that it can be further simplified. sqrt(-1) is a 90 degree counter-clockwise rotation into the "imaginary" plane from 1 (which is a rotational plane, not a cartesian plane). That's why if you rotate it again (i.e. 1 * i * i) you arrive at -1. And if you rotate twice again you end up back at 1. They can be very useful for doing rotational math in a standard cartesian plane, for example, and avoid doing coordinate-system translations. This is a good article [^] I read awhile ago on the topic. I know in school my teachers never really explained them beyond "they just pop up so you need to know the rules", so I never developed any intuition on what they meant. A quote from the article, attributed to Carl Gauss:

                                  If +1, -1, √-1 had not been called a positive, negative, imaginary (or even impossible) unit, but rather a direct, inverse, lateral unit, then there could hardly have been any talk of such obscurity.

                                  0 Offline
                                  0 Offline
                                  0x01AA
                                  wrote on last edited by
                                  #16

                                  Sorry for that question, but at the moment I'm too lazy to think in deep for it... The sqrt of a positive number x has always two solution +/- (abs(sqrt(x))). How it is about the sqrt of a negative number? Are there also two solutions? Sorry again, to be that lazy and simply ask for it ;)

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                                  • C CPallini

                                    Physicists do the same all the time.

                                    "In testa che avete, Signor di Ceprano?" -- Rigoletto

                                    N Offline
                                    N Offline
                                    Nelek
                                    wrote on last edited by
                                    #17

                                    CPallini wrote:

                                    Physicists do the same all the time.

                                    Presuppose they don't :laugh:

                                    M.D.V. ;) If something has a solution... Why do we have to worry about?. If it has no solution... For what reason do we have to worry about? Help me to understand what I'm saying, and I'll explain it better to you Rating helpful answers is nice, but saying thanks can be even nicer.

                                    1 Reply Last reply
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                                    • 0 0x01AA

                                      Sorry for that question, but at the moment I'm too lazy to think in deep for it... The sqrt of a positive number x has always two solution +/- (abs(sqrt(x))). How it is about the sqrt of a negative number? Are there also two solutions? Sorry again, to be that lazy and simply ask for it ;)

                                      K Offline
                                      K Offline
                                      Kenneth Haugland
                                      wrote on last edited by
                                      #18

                                      x^2 - 1 = 0 x = +/- sqrt(1) => x^2 = 1 x^2 + 1 = 0 x = +/- sqrt(-1) => x^2 = -1

                                      1 Reply Last reply
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                                      • 0 0x01AA

                                        Sorry for that question, but at the moment I'm too lazy to think in deep for it... The sqrt of a positive number x has always two solution +/- (abs(sqrt(x))). How it is about the sqrt of a negative number? Are there also two solutions? Sorry again, to be that lazy and simply ask for it ;)

                                        J Offline
                                        J Offline
                                        Jon McKee
                                        wrote on last edited by
                                        #19

                                        The reason for the +/- is not due to imaginary numbers, it's a byproduct of how square roots are defined in general. Squaring a number removes sign information, so while we can reverse the process to determine the magnitude of the original value, we can't regain the sign information* so we put +/- because we don't know. *: You can reason about and figure this out sometimes, but it relies on the specific problem and how it's constrained.

                                        1 Reply Last reply
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                                        • J Jon McKee

                                          I'm slightly leaning into your statement, but to be fair to mathematicians, they can calculate sqrt(-1). It's sqrt(-1). It's a misunderstanding of what an imaginary number is to assume that it can be further simplified. sqrt(-1) is a 90 degree counter-clockwise rotation into the "imaginary" plane from 1 (which is a rotational plane, not a cartesian plane). That's why if you rotate it again (i.e. 1 * i * i) you arrive at -1. And if you rotate twice again you end up back at 1. They can be very useful for doing rotational math in a standard cartesian plane, for example, and avoid doing coordinate-system translations. This is a good article [^] I read awhile ago on the topic. I know in school my teachers never really explained them beyond "they just pop up so you need to know the rules", so I never developed any intuition on what they meant. A quote from the article, attributed to Carl Gauss:

                                          If +1, -1, √-1 had not been called a positive, negative, imaginary (or even impossible) unit, but rather a direct, inverse, lateral unit, then there could hardly have been any talk of such obscurity.

                                          J Offline
                                          J Offline
                                          jschell
                                          wrote on last edited by
                                          #20

                                          Jon McKee wrote:

                                          I know in school my teachers never really explained them beyond

                                          Unfortunately there are very many people that do not understand proofs. And even for those that do (or claim so) they don't understand what assumptions and definitions really mean for those proofs.

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