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Probability of waking up tomorrow

  1. Dec 8, 2013 #1
    Long story short, me and friend arguing about stuff. I said believing in something without evidence is stupid. He then asked me a question that i thought I had the answer to but well he said

    "will you wake up tomorrow?"

    I said of course. then he replied

    "Show me evidence or proof?"

    Then I kinda lost it and said that the probability is high. He said probability leaves room for error, and that because I showed him no evidence/proof i was a hypocrite and he said I also was wishful thinking

    I havent come back at him, what can i say to him to be right?
  2. jcsd
  3. Dec 8, 2013 #2
    Some crude calculations based on the assumption you do indeed live in Australia as per my deductions and belong to 15-24 age group.
    Approx. 1-0.0000236= 0.9999874 unless you don't sleep tomorrow.
    EDIT: or sleep the whole day through. further investigation shows i might be wrong about austrailia as New Zealand is also a distinct possibility but as we are talking probabilities I am sticking with Australia.
  4. Dec 8, 2013 #3
    is that a serious probability? wow how did you come to that number?

    i gave my age in one of the threads and why australia or new zealand?
  5. Dec 8, 2013 #4
    You mentioned Mortein to kill spiders...common in Australia and NZ. I pulled off stats of the age group's mortality rate and divided it by population of that age....wait I made a boo boo....I am stupid.
    [STRIKE]Calculations in progress[/STRIKE] Done:
    74.2 per year per 1000
    so...74.2/365 in a day and for one person hmmm...72.4/(365*1000) = 0.00020328
    Last edited: Dec 8, 2013
  6. Dec 8, 2013 #5
    lol.. mortein is exported to south eastern asian countries (as far as india) and oceania as well, but i guess you're assuming aus/nz cuz my english is reasonable

    lmao @ 18

    are you really 18? wow
  7. Dec 8, 2013 #6


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    To make predictions one uses a model developed from existing evidence. Current evidence shows that you are healthy, require sleep, tend to sleep a usual amount etc. Therefore the model would predict that yes you will wake up tomorrow. Better still this model can be tested.

    Making testable predictions from models, even if they are probabilistic (i.e. there is a small chance you wont wake up) is entirely rational and usual. It isn't believing without evidence.
  8. Dec 8, 2013 #7
    We were talking probabilities...

    Significant figures only and rounded off (The zeroes didn't fit.)
  9. Dec 8, 2013 #8


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    I think you're confusing "evidence" with "absolute certainty."

    A "scientist" never has absolute certainty on anything. But all of our models are based on evidence that they are either consistent with or inconsistent with and when there is enough evidence to suggest that a model is incorrect it is (or at least is supposed to be) abandoned.

    Personally I think everyone has a little part of their brain that's always assessing probabilities (or prospects if you've read any of Daniel Khaneman's (sp?) work). We make decisions based on estimated probabilities and we derive those estimates from available evidence. There is a lot of evidence to show that we don't inherently do this correctly. We tend to over-estimate very low probabilities for example. But when we're thinking rationally, we can get it right. That doesn't give us certainty though.

    I don't know for certain that I'm going to wake up tomorrow. But the evidence I have is that for a man of my age, in my state of health, in the absence of mitigating conditions (I don't live in a country that's at war, I don't owe any mafia kingpins money, etc.) the probability of waking up is so extremely high that I gain nothing by entertaining the alternative.
  10. Dec 8, 2013 #9


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    That is probably wrong, because most people in that age group don't die in their sleep. They tend to die doing things while they are awake but not using their brains.

    Apart from infants, and young adults doing stupid things, human mortality follows a fairly simple age-related pattern: http://en.wikipedia.org/wiki/Gompertz–Makeham_law_of_mortality
  11. Dec 8, 2013 #10
    Well, if he dies today he isn't going to wake up tommorrow, is he?
    (Darn! I forgot to take zombie apocalypse into account.)
  12. Dec 8, 2013 #11
    Tell him you've become aware that there is an invisible, undetectable, weird purple jellyfish sitting on his head. He should believe it without question, despite the possibility of evidence or proof. If he doesn't, he's a hypocrite.
  13. Dec 8, 2013 #12
    Okay, I googled the probability of a zombie apocalypse:
    • Naturally toxoplasma gondii came up (brain controlling parasite infects about 50% of the population, no not joking) but those are alive humans so still would need to sleep and wake up. (won't affect my probabilities)
    • Fugu poisoning and revival through alkaloids...well still needs to wake up. (Only thing on the list that could be remotelytermed death.)
    • Creutzfeldt-Jakob disease...still needs to sleep and wake up. But can't be called death.
  14. Dec 8, 2013 #13
    Reminds me of:
    Invisible Pink Unicorns are beings of great spiritual power. We know this because they are capable of being invisible and pink at the same time. ███████████████████████████████████████████████████████████████████████ We have faith that they are pink; we logically know that they are invisible because we can't see them.
    -Steve Eley source-Wikipedia
  15. Dec 8, 2013 #14


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    Maybe I'm over-thinking this, but a transition from "alive and awake" to "dead" doesn't count by my logic. You can only wake up after being "alive and asleep".
  16. Dec 8, 2013 #15
    Yes and since he is already dead (RIP Caveat :devil:) he can't wake up regardless of how he died:sleeping or otherwise...
    o:)zombies better stay with collinsmark
  17. Dec 8, 2013 #16
    Your friend is silly.

    A high probability is all we can ask for. There are no certainties in science. You can tell him that "the probability is so high that it would be perverse to believe otherwise."
  18. Dec 8, 2013 #17


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    .... unless he speaks Hebrew, where it is perfectly logical to say "and when he arose in the morning, behold, he was dead". (See 2 Kings 19:35).
  19. Dec 8, 2013 #18


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    This is really easy. The evidence is that you woke up today, yesterday, the day before that, etc. I wouldn't bother trying to calculate the probability - it really shouldn't matter for such a basic question.
  20. Dec 8, 2013 #19


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    Circumstantial evidence: humans invented calendars.
  21. Dec 9, 2013 #20
    The fact you've awaken every day of your life so far is not evidence you'll wake up tomorrow. We know this because everyone eventually doesn't wake up tomorrow in the end, regardless of how many days in a row they have chalked up. In fact, the more days that accumulate that you do wake up, the more and more likely it becomes you won't wake up the next day. While being alive is a fact, it is a fact that will change suddenly at some point over time, in some cases, quite unpredictably.

    He really should not have said, "Of course." The best answer would be, "I don't know for certain."

    That, though, is a whole different proposition than believing in something for which there is no evidence, like ghosts, bigfoot, or visits from extra-terrestrials. These latter things have never been incontrovertibly proven to exist, have never enjoyed the status of 'fact'. The expectation that will ever change is unwarranted. The expectation that someone who is alive today will be alive tomorrow is usually well warranted, though not proven or guaranteed.
  22. Dec 9, 2013 #21
    Use proof by [strike]induction[/strike] intimidation. :rofl:
    Last edited: Dec 9, 2013
  23. Dec 10, 2013 #22


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    You might want to start with an actuary table.

    Here is one for the United States (based on 2009 data). One column gives the probability of dying within one year. Perhaps you can find a different actuary table one tailored to your specific location. That and an acceptable mathematical model you could calculate the probability of dying by the next day. (Back of the envelope might be just dividing by 365, depending on how you want to go about it.)


    So when asked to show evidence, there ya go. Show him the table; show him the math. There's the evidence. (That might not be the only piece of evidence. And its applicability might be further refined depending on your specific health condition and whatnot. But it's evidence none-the-less.)

    [Edit: if the probability of dying within 24 hours is p24h, then the probability of not dying in that timeframe is 1 - p24h. Of course, this doesn't account for being really, really sleepy the next day, or something like that, that would just temporarily keep you from waking up.]

    Zombies!? :eek:
    Last edited: Dec 10, 2013
  24. Dec 10, 2013 #23
    You woken up once the first day of your life. You woken up yesterday and because of that you woken up today. Therefore by mathematical induction you are going to wake up every morning forever.QED.
  25. Dec 10, 2013 #24
    Yep. Make it three days and you're guaranteed immortality!
    Last edited: Dec 11, 2013
  26. Dec 11, 2013 #25
    yeah thanks for the replies guys

    he actually smarter than me, he works for Boeing and was a professor, also has a phd in aerodynamic engineering so he's not an idiot and probably knows more about physics/maths that i could possible envision

    so bringing him maths is kinda pointless lol i respect his beliefs though
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