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location Seattle, WA
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visits member for 2 years, 2 months
seen Dec 24 at 1:15

I participate on this site because I really enjoy physics and because I would like to learn more about what makes an online community work well. Questions often interest me more than answers – although I think the best answers are grounded in observation and experiment. I’m optimistic that there are still many surprising discoveries yet to be made in the physical sciences. I believe physicists should be good citizens. I believe my children will know things about the natural world I can’t even imagine – and will learn them in ways quite different than how I was educated.


Jun
10
comment Can Aluminium be softened
Good catch. The reference figs I linked to are actually shown in F degrees, I wrote C, I corrected the answer. Thanks
Apr
21
comment Effect of CO2 on the environment, besides greenhouse effect and ocean acidification
I think this question needs to be more specific. Are you asking what physical effects (measurable) CO2-concentration has on the atmosphere?
Apr
12
comment If the MH370 black box did sink to 15000 ft, how long would it have taken?
Yes good answer, but what might the bounds be on your solution given the piece containing the box is smaller than the 777 and no larger than the box itself. And how deep is the Indian Ocean?
Apr
5
comment Earth as a conductor and emf produced?
The basic physics and math of magnetotellurics is described here
Apr
5
comment Earth as a conductor and emf produced?
Magnetotellurics is the term used for the geophysical technique used to probe the Earth's electrical properties (crust and mantle.)
Apr
2
comment Could one measure a stick to an arbitrary precision by having its length estimated by enough people?
If the motion of the ship added imprecision to the clocks, it might not matter how many clocks you had, if they were all on the same ship ... they could all become equally impaired
Apr
1
comment Could one measure a stick to an arbitrary precision by having its length estimated by enough people?
What if everyone had a different measuring rule manufactured in the same factory - and made of green wood - which shrank 0.1% over time? The inaccuracies would not average out.
Mar
28
comment Tsunami dampening mechanisms
This recent paper published in Nature: Taming hurricanes with arrays of offshore wind turbines immediately came to mind when I read your question.
Mar
25
comment How do we know that earth is not perfect sphere?
+1 Good point - I have responded to your comment in the answer body
Mar
24
comment Why is the geomagnetic north pole at a different location from the magnetic north pole?
Another way to say this is that the geomagnetic poles are by definition required to be antipodal (it's the best fit to a dipolar field.) The observed magnetic poles are not so required.
Mar
24
comment What is the longitudinal difference between the sub­solar point and the magnetic poles at time $t$ (hours)?
You should be able to obtain the longitude of the solar point at t from that calculator. Check the reference where you obtained that formula to determine the sign convention - otherwise you might try a simple case you know the answer to determine the sign convention. Also be sure to take care with your units.
Mar
17
comment Are leptons, baryons and energy the only products of radioactive decay?
@Brandon Enright - An element is defined by it's atomic number. A nuclear reaction that changes the atomic number transmutes the reactant atoms into atoms of other elements plus (possibly)other products. Anna's answer explains, as I understand it, that at high energy the products would include 'elementary particles' - which is also properly referred to as 'matter'- although at this scale the duality of matter/energy and particles/waves become significant.
Mar
14
comment what determines the wavelength of waves on the open ocean?
What may not scale well is the action of the model boat bobbing in the water.
Mar
14
comment what determines the wavelength of waves on the open ocean?
I believe your graph is showing a single slice of the boundary of a "fully developed sea" which is a theoretical maximum limit of the size of wind waves. Larger actual waves have been observed. Wind fetch and duration are also shown in that table as having comparable effect as wind velocity.
Mar
13
comment If a planet were cut in half but stayed hemispherical, how hot would the ocean on the flat side be?
I think questions about hypothetical game situations probably aren't covered here. The moderators will most likely close this unless you can pose your question for a real physical situation.
Mar
7
comment Meteorite from Mars?
Hard to imagine a process that would lead to such 'noise.' Note that the first four elements are 'noble gasses' - these they do not chemically react with other elements to form compounds that might alter there abundance in the sample. I think @DavePhD is still correct to say (even 15 years later) that meteorite-geochemists think the Mars hypothesis is highly probable.
Mar
7
comment How is this process not quasi-static yet reversible?
I think your question would be much easier to understand if you included a drawing of the system you are describing.
Mar
4
comment Meteorite from Mars?
Good answer, thanks for including those references. I am unable to vote up, but will retry later. Because many of the readers on this forum are not chemists, you might also want to include an explanation that the evidence is a combination of major element, trace element, and isotopic evidence.
Mar
2
comment The physics of sound boards
Yes but a sound board would have multiple harmonics.
Mar
1
comment about vosges landscape and natural water transportation
You basically have the right idea. Horst and graben terrains are caused by parallel faults in the Earth's crust, these are German words and apply to the Rhine valley. Anticline and Synclines refer to folds in the crust. Not familiar with structural geology of the Vosges Mountains, but you might try searching the web for resources on Tectonic Geomorphology.