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Cabal · Nov 26, 2009

brinny said:
Wow! i didn't know that.

Solar variation - Wikipedia, the free encyclopedia

The average amount of solar power per square meter on Earth is about 1.13 watts, if you focus a bit of that down to a spot, it'll get hot.

A lightbulb by comparison has only about 60W power to begin with and then rapidly spreads out and more than likely just loses its power warming the surrounding air.

And incidentally, this is similar to why lasers can be fairly dangerous, they have a high operating power and usually the beam spot size is very small.

brinny · Nov 26, 2009

Cabal, still wonderin'

Originally Posted by Cabal
Physics, clearly.

brinny: describe yer dance fer joy

mine is sort' like this:

canehdianhotstuff · Nov 26, 2009

Cabal said:
I'm not sure myself. Each dice roll is independent of all the others and whether you state it or not should have no effect on the probability.

For any one roll of a set of 6 dice coming up, the odds are (1/6)^6 = 1 / 46716, as each dice roll does not affect the other.

I suspect you maybe confusing it with a different system like a deck of cards, drawing a particular set at random without replacement has the odds 1/52 * 1/51 * 1/50 * 1/49 etc.

There is a fundamental difference in probabilities for whether order is important or not (permutation vs combination) but I don't think it applies here as the dice are ultimately treated as indistinguishable from each other.

It's more complicated than that because you get three rolls, and on the first roll you can get let's say 3 of kind. If you continue through for the yahtzee you then have 2 dice at a (1/6)^2 probability of getting what you need. If you go through all the possible outcomes from first roll onwards with the binomial formula you end up with a 1/22 or 4.6% chance of a yahtzee.

Cabal · Nov 26, 2009

shawn101 said:
It's more complicated than that because you get three rolls, and on the first roll you can get let's say 3 of kind. If you continue through for the yahtzee you then have 2 dice at a (1/6)^2 probability of getting what you need. If you go through all the possible outcomes from first roll onwards with the binomial formula you end up with a 1/22 or 4.6% chance of a yahtzee.

Duh, quite clearly I forgot the rules of yahtzee, it's been a while since I played. @ self.

Yeah, forgot that you can hold some dice and reroll.

Nevermind then!

AV1611VET · Nov 26, 2009

Cabal said:
Duh, quite clearly I forgot the rules of yahtzee, it's been a while since I played. @ self.

Yeah, forgot that you can hold some dice and reroll.

Nevermind then!

Actually I meant in one single roll.

gipsy · Nov 26, 2009

AV1611VET said:
Is this correct?

The chances of rolling a Yahtzee are 1-in-120.

The chances of rolling a [predetermined] Yahtzee are 1-in-720.

If I just throw the dice and six 1s come up, that's 1-in-120, or 1/5 x 1/4 x 1/3 x 1/2.

But if I say beforehand that I'm going to roll six 1s, then the chances are 1-in-720, or 1/6 x 1/5...

Is this correct?

Without going directly into the numbers themselves:

If you want to get any yahtzee with one throw, then the probabilities for your 5 dices should be: 1/1, 1/6, 1/6, 1/6, 1/6 because it doesn't matter what the first dice shows, the other 4 always have a possibility of 1 in 6 to show the same number as the first one.

If you want to specifically get an yahtzee with the number "5" for example, then the probabilities are: 1/6, 1/6, 1/6, 1/6, 1/6 because every dice has to show "5" ...

So the chances to get any yahtzee are bigger than to get a predetermined yahtzee ...

canehdianhotstuff · Nov 26, 2009

gipsy said:
Without going directly into the numbers themselves:

If you want to get any yahtzee with one throw, then the probabilities for your 5 dices should be: 1/1, 1/6, 1/6, 1/6, 1/6 because it doesn't matter what the first dice shows, the other 4 always have a possibility of 1 in 6 to show the same number as the first one.

If you want to specifically get an yahtzee with the number "5" for example, then the probabilities are: 1/6, 1/6, 1/6, 1/6, 1/6 because every dice has to show "5" ...

So the chances to get any yahtzee are bigger than to get a predetermined yahtzee ...

That is correct. I had started off my other post with only one roll and hence you can ignore the first die cause he has no hindrance on the last 4 being the same. So a (1/6)^4 chance on the first roll.

catzrfluffy · Nov 26, 2009

Wiccan_Child said:
Nope. We're called limeys for a reason .

Actually limes contain very little Vitamin C, that's why we all got scurvy.

The man died from eating a poisoned popsicle, by the way.

AV1611VET · Nov 26, 2009

gipsy said:
Without going directly into the numbers themselves:

If you want to get any yahtzee with one throw, then the probabilities for your 5 dices should be: 1/1, 1/6, 1/6, 1/6, 1/6 because it doesn't matter what the first dice shows, the other 4 always have a possibility of 1 in 6 to show the same number as the first one.

If you want to specifically get an yahtzee with the number "5" for example, then the probabilities are: 1/6, 1/6, 1/6, 1/6, 1/6 because every dice has to show "5" ...

So the chances to get any yahtzee are bigger than to get a predetermined yahtzee ...

Thank you, gipsy; that's what I thought.

My mistake was lowering the denominator, instead of keeping it at 6.

TerranceL · Nov 26, 2009

Wiccan_Child said:
I don't think it's the higher wavelength of the photons, since the shortest wavelength produced in any significant number is really just ultraviolet.

Yellow is the Sun's spectrum as seen in space, red is as seen on Earth (as you can see, the atmosphere absorbs certain chunks of it), and the grey line is the black-body spectrum (basically, an ideal object that emits light solely as a result of it's temperature, which is a good approximation of the Sun's emitted spectrum).

Weird.

Wiccan_Child · Nov 26, 2009

AV1611VET said:
Is this correct?

The chances of rolling a Yahtzee are 1-in-120.

The chances of rolling a [predetermined] Yahtzee are 1-in-720.

If I just throw the dice and six 1s come up, that's 1-in-120, or 1/5 x 1/4 x 1/3 x 1/2.

But if I say beforehand that I'm going to roll six 1s, then the chances are 1-in-720, or 1/6 x 1/5...

Is this correct?

... what's a 'Yahtzee'? I'm assuming it involves dice.

EDIT: Page 100! *breaks open a bottle of very cheap champagne*

AV1611VET · Nov 26, 2009

Wiccan_Child said:
... what's a 'Yahtzee'? I'm assuming it involves dice.

Yahtzee is a dice game where your turn consists of rolling five dice and trying to meet the following obligations:

--- upper section ---
Aces
Twos
Threes
Fours
Fives
Sixes
--- lower section ---
3 of a kind
4 of a kind
Full House
Sm. Straight = sequence of 4
Lg. Straight = sequence of 5
YAHTZEE = 5 of a kind
Chance

You get three rolls.

Say it's your turn and you roll all five dice, and they come up 5,5,5,5,4.

You can then roll the 4 two more times and try to get a 5 so as to Yahtzee.

If you don't, you can either place your score in the Fives up above, or the 4 of a kind in the lower section.

AV1611VET · Nov 26, 2009

Wiccan_Child said:
EDIT: Page 100! *breaks open a bottle of very cheap champagne*

Kid stuff --- 219164 ---

Wiccan_Child · Nov 26, 2009

AV1611VET said:
Kid stuff --- 219164 ---

Good God, that's an abomination!

gipsy · Nov 26, 2009

AV1611VET said:
Kid stuff --- 219164 ---

Asking the "physicist AV1611VET" : could you explain me what it is you gain with such pointless activities?

AV1611VET · Nov 26, 2009

gipsy said:
Asking the "physicist AV1611VET" : could you explain me what it is you gain with such pointless activities?

Do I have to gain something before I engage in "pointless activities"?

Cabal · Nov 26, 2009

AV1611VET said:
Do I have to gain something before I engage in "pointless activities"?

Indeed, twas a bit of oxymoronic question!

AV1611VET · Nov 26, 2009

Cabal said:
Indeed, twas a bit of oxymoronic question!

I get those.

Questions with insulting adjectives in them, questions with the answer (or the answerer) prejudged.

IOW, the standard format.

Bushido216 · Nov 26, 2009

Hey, physicists.

So, I had an idea for a story running through my head and I wanted to ask a few physics related questions.

1. Let's say hypothetically some As Fast As Light (AFAL!) device grabs me by the wrist and near instantaneously accelerates to relativistic speeds. What happens to me? I'm assuming something like "you get torn apart at a sub-atomic level".

2. I get vaguely the idea of "moving through time" and it needing its own dimension (axis). As one does anything time is ticking off. I'm not sure about the inverse relationship between speed and the speed of time (going faster means you move more slowly through time). Is this a basically a D=VT sort of thing? i.e., the more quickly you move the less time it takes to get to that distance? Or what's the relationship (in a nut shell).

3. What basic sort of structural concerns are inherent in AFAL travel? I assume that you'd need some pretty seriously built space-ship. i.e., you'd need to make sure that everything got kept together. If the ship is moving AFAL, so are the passengers! How slowly would said ship have to accelerate to keep from pulling itself apart?

Thanks.

gipsy · Nov 27, 2009

AV1611VET said:
Do I have to gain something before I engage in "pointless activities"?

OK, I get it ... the question wasn't phrased very well, so I rephrase it

What's your intention doing these counting threads?

[edit] ... woohoo ... I'm #1000 [/edit]

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