h2g2 The Hitchhiker's Guide to the Galaxy: Earth Edition

I just wonder how many stars in a Universe?

unfortunately the universe completely disproves itself...

if there is an infinite amount of space in the universe THEN theoretically there must be an infinite amount of planets in it (following so far) thus the infinite amounts of planets would completely fill the infinite amounts of space thus no space left thus unless the universe is one great big mass of rock it can't be infinitely big or it does not have an infinite amount of planets...

so space can only be so big putting a kind of restriction on it

... thus proving that mathematics are not neccesserely (sp?) the answer.

Remeber that a massive piece of rock mainly consists of the space between the particles.

(my brother is a shoesalesman, but you may call me) JAR

nope.
infinitive doesn't equal infinitive...
lets take a simple example :
there are whole numbers,like 1 or 42 or -13 and there are fractions, as one and a half or 5.8763.
as you can easily find out by counting, there is an infinite amount of whole numbers.
but as you can see by continuing the sequence 1/2 , 1/3 , 1/4 ... there are infinite fractions even between 1 and 2...
so it is proven that the amount of fractions is of a greater infinity as the amount of whole numbers.
qed

Uhm...

So if you divide the number of whole numbers (infinite) with the numer of fractions (infinite) you would get an answer somewhere between zero and 1?

JAR

First I would like to address Lucifersprohpet about his statement "the infinite amounts of planets would completely fill the infinite amounts of space thus no space left thus unless the universe is one great big mass of rock it can't be infinitely big or it does not have an infinite amount of planets."

This is a load of hogwash. How can you fill infinite space? The answer is, you can't. Even with an infinite number of planets. Here is where you loose the understanding that infinity cannot be filled. Stating that if space is infinite and that the number of stars is also infinite, then one must fill the other shows a lack of understanding of the term(not word) infinity [sorry I mean no offense by this last statement]. This is something that we (as mere humans) have great dificulty even comprehending the idea of infinity.

First you must fully understand the meaning of infinity. When you do, you will understand why there can be an infinite number of stars and planets and space itself.

Question: Can you wrap somthing(even an intinite somthing) around something that is infinite?

Question: If you have infinite speed, how long will it take you to cross infinite space?

Question: Can an infinite amount of water fill a cup of infinite size?

Question: Can a 6 oz african swallow carry a 2 lbs coconut?

The last question is optional.

Noj Trebor

Question: Can you wrap somthing(even an intinite somthing) around something that is infinite?

In light of other discussions around the guide hinting at infinities of varying size, I'd say "Yes". However, I admit to being very much ignorant of the full meaning of the word.

Question: If you have infinite speed, how long will it take you to cross infinite space?

I wonder when we get travel without movement... Could this have anything to do with correlated lightparticles? (Another subject I know next to nothing about)

Question: Can an infinite amount of water fill a cup of infinite size?

Yes. Were it coffee, it could not. There is never enough coffee.

Question: Can a 6 oz african swallow carry a 2 lbs coconut?

An age old question. Can I suggest a read-up of Arthurian Mathematics? The answer is of course "Yes".

A grand poll. Very much enjoyed!

Ahh but then the African Swallow, being non-migratory, wouldn't have anywhere to carry it anyway would it! Unless of course, it wanted it as a nice ornament for it's nest, but then where in Africa would one find a coconut? Unless of course it had been left there by two European Swallows, who had carried it there whilst migrating, using a piece of string tucked under the dorsal feathers!

the biggest problem here is that nobody knows if the universe is, in fact infinite. Furthermore, nobody will ever know. Astronomers know that the universe is at least 13.5 billion lightyears across because they have observed stars and phenomena at a distance of 13.5 billion light years away. However, beyond that they can know nothing. Recent studies have shown more and more convincingly that the universe is not only expanding but that as an object gets further and further away, its speed away from the observer (e.g. earth) becomes greater and greater. Thus, all the "visible" space that we see will soon (in a couple of billion years) have receded completely. Leaving us lonely and dark. Thus, we see as much of space as we are ever likely to and noone can say whether the universe goes on into infinite.

As for the original question, I beleive there is an estimate of VISIBLE stars, but I am not sure what it is. I will find out asap, tho.

The word infinite is defined as being subject to no limitation or external determination. Therefore, it is impossible for us to ever see, count, or imagine in any form as there is no other thing like it. This is where most of us become confused, for, as humans, we have difficulty comprehending that which we are unable to view in some form and therefore learn.

On the original statement about infinite space and infinite planets what you should consider is that the number of planets and stars is infinite because space is infinite. There is no place in space where you could not see, even distantly, a star or planet. Just because there is an infinite number of stars and planets does not mean they are filling every blank spot in the universe. I believe you may have the ideas of infinite in mass and infinite in number mixed up.

Question: Can you wrap something (even an infinite something) around something that is infinite?

When we consider space, or anything for that matter, to have infinite mass we are considering it to be extending in every possible direction for some infinite distance. Therefore, no matter how we try we cannot get to the out side to wrap it no matter how large the wrapping material is.

Question: If you have infinite speed, how long will it take you to cross infinite space?

First, on the idea of infinite speed, this is quite impossible as the term has once again been taken out of context. Whole numbers extend to infinity and it is entirely true that speed can go to any number within that spectrum. However, no matter what speed you are traveling at it will always be defined as some number. Even the largest number we can imagine has an infinite amount of numbers higher then it.

Next, on crossing infinite space, this too is impossible because as space is infinite and therefore has no boundaries or outer edge.

Question: Can an infinite amount of water fill a cup of infinite size?

No cup, no matter how large, the cup would not be able to get outside of the water to contain it. Something infinite in mass cannot contain another object infinite in mass because they are, by definition, the same size. If the object being contained was instead infinite in number this case would be different. Lets say, for example you had an infinite number of cups, normal size, within an infinite amount of water. This is possible, for as the water would never end, neither would the cups within it. This should not apply that all the cups are touching. Imagine a piece of paper. In the middle of this paper you draw a tiny shape. You then photo copy this paper an infinite amount of times and place all these copies side by side. There would then be an infinite number of cups, none of them touching.

And if its speed gets greater and greater the further away it gets then as a result at an infinite distance it's speed must also be infinite. There's a thought

It is actually impossible to travel at an infinite speed. Infinite speed is faster then the speed of light and, according to Albert Einstein and the Physics community, it is impossible to travel this quickly.

Sorry, couldn't resist a comment on LordHelmchen's infinite fractions thing. Right idea, wrong set: there are the same 'number' of fractions (rational numbers) as there are integers. This is easy to see by finding a function which 'maps' fractions to (positive) integers, like this one:

f(x,y) = 2^x . (2y + 1)

where '^' denotes exponentiation, '.' denotes multiplication, and x and y are respectively the numerator and denominator of the fraction in question: x/y. By thinking a little about this, you will see that not only does this function map every pair of numbers to a UNIQUE integer, every integer can be mapped to a UNIQUE pair of numbers in a similar way. Therefore, since for every fraction there is an integer and vice versa, the 'number' of integers is the same as the 'number' of fractions. There are also as many positive integers as there are positive and negative integers combined, which is kind of weird, too.

However, there are more REAL numbers than there are integers (real numbers include all decimal numbers, not just fractions; things like pi, and the square root of two). However, the proof is a little more involved, and I can't quite remember it.

Stars are everywhere, it's just a matter of time before you fall asleep forever, i.e to die, and then you will find the truth about the stars and it's quantity of the stars in the sky above. till then it will be very difficult for not only you but for many of us in earth to give the exact figure.

Ref Post 1, this is my answer to the q posted in a different thread pertainin to A3005984, "If Earth were the size of a pea": http://www.bbc.co.uk/dna/h2g2/brunel/F1887283?thread=484392&latest=1 I'll have to post it in the following post as I've 'dropped' whart I needed to cut and paste. continued....

I've seen it said that there are "more stars in the Universe than all the grains of sand on every beach and every desert on Earth" (70 thousand million, million, million = 70 sextillion or 70 x 10 to power 21. (see Genesis 22:17).(Incidentally, I've just realised that this is somewhat smallesr than Avogadro's Constant, which is in my mind at the monment (6.023 x 10 to power 23).

"First you must fully understand the meaning of infinity. When you do, you will understand why there can be an infinite number of stars and planets and space itself."

I agree;

Who said that if there was infinity of planets, they would be together, and space would be a rock as such? If the universe and space is infinite then obviously an inifite amount of planets and stars is possible.


I may be wrong but i understood it that infinity was not a set number.

Basically if there is infinite space, then as many planets (infinite) would be possible because there is never ending space.

'not limited by person or number' 'boundless, endless'


. . .Or have i got this completely messed up?

The number of galaxies in the observable universe is estimated to be around 100 billion. Each of those contains approx 100 billion stars. The total number of stars in the universe is probably around about 10 thousand billion billion, give or take a few hundred.

The figure I wrote down in my notes is "more stars in Universe than all the grains of sand on every beach and in every desert in the World (see Genesis 22:17). Thiis is estimated as 70 sextillion (70 thousand million million, or 70 x 10 to power 21)

and to think over 90% of space is dark matter...
http://www.bbc.co.uk/science/space/deepspace/darkmatter/

It's a big sky