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

Entry: If Earth were the size of a pea - A3005984
Author: malmcgo - U888937

Let's try to get to grips with the size of the universe. You know if you stacked a 0.1mm thick sheet of A4 paper for every kilometer between us and the edge of the universe (i.e. the extreme observational limit) your paper column would be 44,500 trillion kilometers high. This quantity equates to 12 hundred paper columns reaching out to Proxima Centauri. The warehouse which supplied the paper would need to cover the entire surface of the earth, wet bits included, have a ceiling 5.6 kilometers high, and have no room left over for a stacker truck. Put another way, you would have to completely blanket the planet with A4 and repeat the exercise 56 million times to have a thin sheet of paper for every kilometer between us and the end of the known universe.
Hmm.... interesting. But what if the universe were shrunk such that Earth became the size of a pea?

Hi Malmcgo!

Thanks for contributing to the Guide. This is good stuff; informative and amusing as well. But it is very abrupt. Could you give us a more gentle introduction, perhaps starting with the traditional "Space is big".

It ends rather abruptly, as well.

Hi there! I see you're new around here -- have you had a chance to take a bit of a look around yet?

I think once you do, you'll see that Peer Review (which is where we are right now) is for entries trying to get into the Edited Guide, and that those entries tend to be quite a bit different than the one you have here.

Not that what you've written isn't interesting to read, and a bit of fun as well -- it's just that Peer Review doesn't seem to be the right place for it.

Here are a few different Edited Guide entries you might take a look at - I tried to pick some ones I thought you might find interesting, or that were a little related to what you wrote about here...

A2591129 - Closest Packings of Bowling Balls and Other Spheres
A578676 - Astronomical Distance Scales
A505630 - Travelling to the Stars
A201790 - Astronomical Units
A1061353 - An Introduction to Metric Spaces
A461972 - Stellar Magnitudes


Mikey

Simulpost!

Interesting way of illustrating the distances . In addition you may like
A2181548 Googol - an Unimaginably Large Number
for a similar thought experiment.

I agree with the points made by Mikey and Gnomon. Are you keen to create an Edited Guide entry? You can get further advice and assistance if you could go via A1355195 Hitchhiking Your Way into the Edited Guide

Pimms

The thought experiment I used to do at work was this (I'm afraid the units will be Canadian):

If the earth were the size of a loonie (that's a coin) then the moon would be a dime three feet down the counter. And the sun would be a ten foot diameter ball in the middle of the first green. (It was a golf course thought experiment.)

I never took it farther than that.

Somehow I think that this entry could actually be made suitable for the guide. I'm not sure exactly how, but I think it could.

Of course, "If Earth were the size of a pea, Jupiter would be the size of an orange" is already a part of a children's book called Planets, by Jennifer Dussling and Denise Ortakales. I'm not shouting plagiarism, however. If you google "If Earth were the size of a pea" without the quotation marks, you'll find that there are more entries than you can shake a stick at with variations on this thought experiment. As I mentioned before, I've used a variation of my own for over ten years.

I think this variation will have to have something very special to set it apart from all the others if it is going to be Edited Guide material.

And it will have to be very different from this one: http://ssastros.org/grape.htm

Well, it's a bit different... But it has potential for the EG. First of all I think that the first-person bits have to vanish. "And it will have to be very different from this one: http://ssastros.org/grape.htm" Well. There *is* actually some similarity. But this Entry is quite different from that one, I think. At least it's not copy-pasted. Plus this Entry has some additional thoughts (like taking 80 billion years to walk across the universe) which I have not found in the one from the link... HELL

As to your first argument, anhaga... IIRC, that this Entry would have to be substantially different from other stuff found in the net... Well. I disagree. Just because there are loads of articles in the net describing the similar thought-experiment, this doesn't mean this one isn't worth inclusion in our guide. I would like to see this in h2g2, because this is a very illustrative experiment. Most Entries, BTW, in the Guide have their counterparts out there in the likes of Wikipedia.

HELL

I mean - of course - they have to be different as not to fall under 'plagiarism'. But the idea, or the topic doesn't have to be unique or absolutely original. (There are loads of Entries about AIDS in the net, but I thought h2g2 also needs one. There are loads of Entries about Trigonometry, but h2g2 deserves its own etc... I like to think about h2g2 being 'as complete as possible')

H

BTW!

As a suggestion, include also the scaling (1:1E9) in the other (i.e. microscopic) direction... If the earth were a (1cm thick) pea, a pea would be the size of an atomic nucleus (10 pm or so - my rough estimate) and a human being would be the size of an organic dye molecule (1.5 nm). The Empire state building would be the size of an endosome (~ 400 nm), and a city would be the size of an blood-cell (10 µm). The state of Texas would be around 1 mm.

HELL

I do think it can be made into EG material.

"Texas would be around 1 mm"

Here's another way to see it.

The earth is for an amoeba more or less what a sphere of 83 light hours would be to us (that's about 10 times the diameter of the solar system, or a little bigger than the solar system plus the Oort cloud - I think). So for an amoeba the earth is already a humongous place.

HELL

I don't think it is good to talk about amoebas because most people have no idea what size they are, never having seen one. I seem to remember that the amoeba is one of the biggest of single-celled creatures and can be as big as 2.5mm across.

OK, Wow, I didn't realize they're *that* big. If that's the case then I must have miscalculated everything by almost two orders of magnitude!!! I would have guessed they're 20-50 µm (2mm is a bit *big*, no?) Use blood cells in the example then (they're the right size, and people know it's tiny)

HELL

Slightly 'off-topic' I'm afraid......Unfortunately, children don't seem to be taught about amoebae any more in school. So, not only are people unaware of their size, they're also unaware of their behaviour, which causes me a problem whemn I'm trying to use them as an analogy for explaining the behaviour of white blood cells, chemotaxis etc etc.

What? They're not taught amoebae! ... I bet it's the government trying to keep us ignorant and docile...

The 'Space Amoeba' formerly known as HELL

Is that a permanent cgange of 'tag'? If people don't know about you, you'll probably be safer?

This is a common phenomenon in my h2g2-life, BIGAL (it happened before). From times to times HELL mutates (into Elvis, Freewheelin' Franklin, the Lobster of Love and now into Space Amoeba). This metamorphosis is usually reversible. In a week HELL'll be back

Yours truly,

The Amoeba from outer Space