APOD: The Scale of the Universe Interactive (2012 Mar 12)

[Tszabeau]

Five bucks says the Estimated Size of the Unknown Universe is low.

[spatrick]

Why is the Top Quark (172,000 MeV) "smaller" than an Up Quark (2.4 MeV)? Is there any such thing as 'density' at these scales?

Yeah, I'm a bit confused by what the authors' intention might be there, as well. In fact, I'm suspicious of everything below the scale 10^-16m, where they say "Lengths shorter that this this are not confirmed". Unless my quick math is wrong, that's only about 12 GeV, and we've been making precision measurements well past that for decades. They describe the Weak interaction as "unmeasurable" and give its length scale as something close to the Higgs's Compton wavelength. (Incidentally, that's the real current limit on measured scales.) Again, the Weak length scale has been measured for decades, and its scale (the W/Z Compton wavelength) is about 10 times larger than what's given. And, what are they trying to express by giving a "size" to the quarks and neutrinos? In the models describing these objects that are best tested by experiment, quarks and neutrinos interact as structureless point (sizeless) objects. The neutrinos are described as being "larger" at high energy than on average, which makes me think maybe they are taking the square root of the total scattering cross section as somehow being the size of the object. Those numbers actually work out roughly correctly to what the authors have given. But the quark sizes? They seem to scale inversely as the quark mass, again suggesting a Compton wavelength. But, if so, then the quarks are being shown as 10^4 or 10^5 "smaller" than they ought to be. Quark total cross sections are a little tricky to pin down, but trying to interpret the lengths here as square roots of cross sections doesn't get anywhere near the right order of magnitude. Maybe they are observational upper bounds on quark sizes? Nope, that's back at the "limit of measured scales". So... the subnuclear world in this presentation seems like a bit of a mess. Well, the Planck length stuff is OK.

Except for that, this is *amazing*. Redoing an updated "Powers of 10" as an interactive Flash is a real stroke of genius. Well done!

[neufer]

Why is the Top Quark (172,000 MeV) "smaller" than an Up Quark (2.4 MeV)? Is there any such thing as 'density' at these scales?

Yeah, I'm a bit confused by what the authors' intention might be there, as well. In fact, I'm suspicious of everything below the scale 10^-16m, where they say "Lengths shorter that this this are not confirmed". Unless my quick math is wrong, that's only about 12 GeV, and we've been making precision measurements well past that for decades. They describe the Weak interaction as "unmeasurable" and give its length scale as something close to the Higgs's Compton wavelength. (Incidentally, that's the real current limit on measured scales.) Again, the Weak length scale has been measured for decades, and its scale (the W/Z Compton wavelength) is about 10 times larger than what's given. And, what are they trying to express by giving a "size" to the quarks and neutrinos? In the models describing these objects that are best tested by experiment, quarks and neutrinos interact as structureless point (sizeless) objects. The neutrinos are described as being "larger" at high energy than on average, which makes me think maybe they are taking the square root of the total scattering cross section as somehow being the size of the object. Those numbers actually work out roughly correctly to what the authors have given. But the quark sizes? They seem to scale inversely as the quark mass, again suggesting a Compton wavelength. But, if so, then the quarks are being shown as 10^4 or 10^5 "smaller" than they ought to be. Quark total cross sections are a little tricky to pin down, but trying to interpret the lengths here as square roots of cross sections doesn't get anywhere near the right order of magnitude. Maybe they are observational upper bounds on quark sizes? Nope, that's back at the "limit of measured scales". So... the subnuclear world in this presentation seems like a bit of a mess. Well, the Planck length stuff is OK.

The electron is represented not by it's Compton "quantum" wavelength:

but rather by it's (~3 orders of magnitude smaller) Classical "electromagnetic" radius:

=

thereby making a "point sized" electron about 4 times the size of a proton or neutron.

I suspect that they have made all the other "point sized" particles
in a relative Classical scale size to this Classical electron.

[mcook]

I really love this presentation of scale. I ran across it for the first time several weeks ago but am glad to see it on APOD.

One element of this presentation puzzles me. At the one nanometer scale, a single hydrogen atom is shown side-by-side with a water molecule, but the hydrogen atoms in the molecule are clearly smaller than the isolated atom. Is this a design oversight in the presentation, or is there some physical phenomenon of which I'm not aware that causes the electron shells in the hydrogen atom to compress when they're shared with the adjacent oxygen atom? (I'm not a physicist and my only formal exposure to the science is three terms of pre-engineering physics in college.)

Anyone? Anyone? Bueller? Anyone?

[deathfleer]

we are perceiving the existence with light waves and some other instruments of perceptions. there may exist something that are not detectable and leave no trace at all on anything.

[monopertuz@yahoo.com]

By all means this APOD is a winner. I've seen other scale type presentation but this one in particular is unique in the interactive capabilities and "down to earth" language used in the explanations and/or descriptions. Adding a touch of humor in some of the descriptions does indeed add to it's readability and enjoyment.

Going through the entire presentation will invariably take a long time. However, it seems that in my quick review I managed to find one item that struck the wrong chord. I honestly believe that the touch of humor may be welcome, but there is however a limit as to what is considered funny and how it is used.

I would like to call your attention to the description of the Large Hadron Collider indicating that 'it smashes protons into each other' and then goes on to say "That's really mean, like bullies at school that smash little children together"

Such a comment is way out of line, sickening and has no place in a presentation of this type.

Hopefully, I will not encounter any other remarks like this when I browse it further.

Fernando Pertuz

[teinoaole]

the entire universe is one great metaphor

[Grammie]

It sounds as if it were fascinating--but I couldn't access(I think that's the word I want) it --being a grandmotherly person with a grandmother computer on dial-up.

[geckzilla]

Aw, Grammie. I'd fix your computer if I were there.

[neufer]

One element of this presentation puzzles me. At the one nanometer scale, a single hydrogen atom is shown side-by-side with a water molecule, but the hydrogen atoms in the molecule are clearly smaller than the isolated atom. Is this a design oversight in the presentation, or is there some physical phenomenon of which I'm not aware that causes the electron shells in the hydrogen atom to compress when they're shared with the adjacent oxygen atom?

Not compressed really. However, the hydrogen electron shells are no doubt shifted laterally in the direction of the oxygen nucleus such as to make it appear that they are compressed in the direction away from the oxygen nucleus.

[Amazin]

There is a proposal that remote galaxy clusters - retreating in their space at many times faster than the speed of light - can be detected by searching for their greatly blue-shifted light, as "the amplitude is not degraded", a scientist explained.

[DavidLeodis]

As there did not seem to be any personal information on Cary and Micheal Huang found directly through the APOD I've done a search and in some information that I found it states "It turns out that "Scale of the Universe 2" was created by Cary Huang, a 14-year-old ninth grader from Moraga, Calif., with technical help from his twin brother Michael". It is an excellent work by them.

[Chris Peterson]

There is a proposal that remote galaxy clusters - retreating in their space at many times faster than the speed of light - can be detected by searching for their greatly blue-shifted light, as "the amplitude is not degraded", a scientist explained.

That makes no sense to me... do you have some reference?

We cannot detect anything which is receding at greater than c. We can- and do- detect distant objects which are currently receding at greater than c, but were not when the photons we now detect were emitted. But those photons are red-shifted, not blue.

[Right, but -]

- space extends with distance, but there is no clean break anywhere in it. It simply extends, so the light is conveyed smoothly from one extending phase of distance to the next, which duly conducts it 'at the speed of light'. For the receiving observer said light is progressively 'red-shifted'. But go far enough, and the red-shift will become null and then reverse to become progressively more and more blue-shifted. Well, that was how a scientst explained it to me, and that 'the signal's amplitude is not degraded'.

[Chris Peterson]

- space extends with distance, but there is no clean break anywhere in it. It simply extends, so the light is conveyed smoothly from one extending phase of distance to the next, which duly conducts it 'at the speed of light'. For the receiving observer said light is progressively 'red-shifted'. But go far enough, and the red-shift will become null and then reverse to become progressively more and more blue-shifted. Well, that was how a scientst explained it to me...

The person who explained this to you was either wrong, or you misunderstood him. The idea has no basis in either theory or observation.

... and that 'the signal's amplitude is not degraded'.

That is an unclear statement. What is meant by "amplitude", "signal", and "degraded" in this context? Amplitude normally means intensity, which is the photon flux. This does decrease with distance, according to the inverse square law. If it is taken as the energy of individual photons, this also decreases with distance, as redshifted photons have lower energy than they would if not shifted.

[Mike Tilley]

At 10^10.1 what is the strangely named "Total Human Height" marker supposed to represent? It's about the same size as the star Pollux.

[bystander]

At 10^10.1 what is the strangely named "Total Human Height" marker supposed to represent? It's about the same size as the star Pollux.

I can only guess that it is the sum total of the height of all humans inhabiting Planet Earth.

[BMAONE23]

At 10^10.1 what is the strangely named "Total Human Height" marker supposed to represent? It's about the same size as the star Pollux.

It represents what would be the total distance if you took every human alive (approximate average height times number of living humans) and layed them, end to end, in a single straight line.
This sounds like a lot of people but you could take all the people currently alive and stand them on the big island of Hawaii with room to spare

[geckzilla]

. . . you could take all the people currently alive and stand them on the big island of Hawaii with room to spare

Using what measurements?

[bystander]

you could take all the people currently alive and stand them on the big island of Hawaii with room to spare

I think I'll plan to be somewhere else that day. There's not that many people I want to be that close to.

[BMAONE23]

. . . you could take all the people currently alive and stand them on the big island of Hawaii with room to spare

Using what measurements?

Figuring that 1sq mi = 27,878,400 sq ft or 3,097,600 sq yds
The big island contains 4028 sq mi.
which equals 112,294,195,200 sq ft
with an approx populace of 7b people
this leaves 16 sq ft per person 4' x 4' square
Cramped to be sure but you could move about and flex your muscles

[geckzilla]

I'd just volunteer for one of the 4 foot squares above the caldera on that day...

[BMAONE23]

It might look a little like this

http://www.progressiveart.com/pitre_over_population.shtml
I have this one at home

Cartainly wouldn't be the Ideal Vacation Spot if the entire world showed up

[neufer]

Volcano Nebula

.

I'd just volunteer for one of the 4 foot squares above the caldera on that day...

Virgo?

<<[Volcano Nebula] galactic dust cloud over the Milk Way Galaxy; seen because of the star shine of most red and blue stars giving it color. Taken with Epsilon 160 F/3.3 astrograph using the SBIG STL-6303 XE CCD Camera; 6-hour exposure; taken in the dark skies over New Mexico. (Image published in Astronomy Magazine, September 2007 Issue.)>>

[Guest]

Wow...totally disappointing you need Flash to watch this.