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One of the most difficult things to get a handle on, when it comes to astrophysics and particle physics, is just what, exactly, what these large and small scales actually mean. While you ponder this, have a listen to Edgar Meyer, Béla Fleck and Mike Marshall's expansive sound as the string trio takes on Fleck's catchy tune,
You might consider a whale "large" and a mouse "small," and perhaps they are when compared to you, but that's only an incredibly tiny fraction of the scales we're talking about when it comes to the Universe. A little over a year ago, I pointed you over to an interactive application showcasing the scale of the Universe. While it was very entertaining, I was also quick to point out that it was rife with errors, and not to be trusted about some matters. But oh, has there ever been an upgrade, and you do not want to miss this!
As we go to larger scales, you can see there are a great many more objects placed in the application, to help you get a handle of relative scale. Where does our Moon fit in the scheme of the great moons of the Solar System? This scale comparison should help give you a great feel for it.
What about planets and stars? A vast array are not only presented here, you may notice a tremendous feature upgrade: each object is annotated, with a small tidbit of information about each specific object in question! Although some of them are silly, other than a few typos, the information is factually accurate! What's also amazing is the difference between these scales. The Moon may be a million times larger than we are, the star, La Superba, above, may be another factor of a million larger than the Moon!
But if you want to pick up an entire galaxy, you need to go a factor of a billion larger than even those huge, supergiant stars! And finally, to encompass the entire observable Universe, you'd need to zoom out another factor of a million. (Which, remember, because space is three-dimensional, is a difference in volume of 1018, or 1,000,000,000,000,000,000!)
And this takes us to the edge of what we can ever see in the whole Universe! Unlike in the previous edition, they get the scale right in the new version, almost like they had read my criticisms exactly, and incorporated my recommended fixes! But it gets even better, because you can zoom down to tiny scales, too. Going far inside a human, which is meter-scaled, you can go way, way down.
While the width of a strand of human DNA may be around a billion times smaller than a human, if you unravelled it and stretched the amount of DNA in any single cell, you'd find it's about ten feet long, or taller than any human being! (And all of that information is available in the annotation!) But what about when we go to the smallest known particle scales? You actually get the information I wished they had included in the first version!
What do they tell you? Lengths shorter than this are not confirmed 100 attometers 1 x 10-16 m All the objects that are smaller than this are unmeasured. The sizes that they appear are only estimates. Some things, like quantum foam, are just parts of theories. They aren't fact. This is pretty close! For instance, if we go down to their particle, "High-energy neutrino," what are we told, and what's actually down there?
The numbers they're reporting are based on the interaction cross-section of these particles, which is what allows you to calculate the probability that they'll collide with another particle. The cross section, of course, is an area (a length-times-width), so you'll need to take the square root of that to get the approximate size, and that's how they get it! This isn't the same as the actual, physical size, which we don't know how to measure. And that's why a low-energy neutrino -- like the ones left over from the Big Bang -- not only have a much smaller cross-section, they haven't even been detected yet!
And finally, if we go all the way down to the limit of what our best quantum theories can predict, to the Planck Scale, beyond which physics breaks down, this is where the most speculative of our theories live. Is there a quantum foam; are there strings and branes? What is the fundamental nature of spacetime at these scales; is it quantized and discrete or continuous? Is there a fundamental quantum theory of gravity or not? Although we don't know, this is where you'd look to find out, on scales 35 orders of magnitude smaller than we are. And all of it, the whole Universe, spans some 63 orders of magnitude, from the smallest sensical quantum scale to the entire observable Universe (and beyond, for the particularly brave), is available for you to explore -- zooming in-and-out as you please -- in this one remarkable toy! Say goodbye to a huge chunk of your weekend, and know that it will be time well spent!