Search found 2191 matches

by thoughtfully
Thu Feb 16, 2017 2:20 pm UTC
Forum: Science
Topic: Walking on a neutronium Dyson Sphere
Replies: 15
Views: 3070

Re: Walking on a neutronium Dyson Sphere

It doesn't involve a Dyson Sphere, but another SciFi reference is Dragon's Egg by Robert L. Forward, a physicist whose SciFi is fairly hard. Humans orbit a neutron star and send a robot to the surface to interact with a technological civilization there.
by thoughtfully
Thu Feb 16, 2017 3:06 am UTC
Forum: Science
Topic: Coincidence in Tycho's Model of the Solar System
Replies: 6
Views: 1673

Re: Coincidence in Tycho's Model of the Solar System

Tycho's system is actually consistent with observations, IIRC. It is just a matter of where you put the origin. A fully geocentric model gets objective stuff wrong, like the phases of Venus.
by thoughtfully
Tue Jan 03, 2017 1:51 am UTC
Forum: Science
Topic: What to Do With a Nearby Black Hole
Replies: 11
Views: 2533

Re: What to Do With a Nearby Black Hole

Sorry about being late to the thread. You magically solve the instability problem, park it at a safe distance, and turn matter into energy at a rather nice efficiency. I seem to recall that Lunar-massed is a convenient size. Has anyone else dealt with one of these?" Very old thread Yeah, it's a...
by thoughtfully
Mon Dec 05, 2016 1:57 pm UTC
Forum: Science
Topic: Miscellaneous Science Questions
Replies: 2835
Views: 534507

Re: RELATIVITY QUESTIONS! (and other common queries)

The energy of a photon can vary depending on the relative motion of the origin/destination (remember, no observations of light unless you are in its path or on the set of Starr Wars!). This is reflected in the wavelength/frequency, however.
by thoughtfully
Wed Nov 30, 2016 10:09 pm UTC
Forum: Science
Topic: Weakening evidence for dark energy
Replies: 12
Views: 2479

Re: Weakening evidence for dark energy

I'm not sure if another citation is needed, but Sean Carroll at Caltech writes an awesome blog and this is his field (cosmology)
https://www.preposterousuniverse.com/bl ... rk-energy/
by thoughtfully
Wed Nov 30, 2016 12:51 pm UTC
Forum: Science
Topic: Miscellaneous Science Questions
Replies: 2835
Views: 534507

Re: RELATIVITY QUESTIONS! (and other common queries)

Can I derail for a second to ask?: thoughtfully mentioned Feynman's QED - how accessible is the text/what level of knowledge does it assume, and how much ground does it cover? I have a very superficial grasp of QFT which I would like to expand on, is all. It's intended for a general audience. There...
by thoughtfully
Wed Nov 30, 2016 4:20 am UTC
Forum: Science
Topic: Miscellaneous Science Questions
Replies: 2835
Views: 534507

Re: RELATIVITY QUESTIONS! (and other common queries)

It's probably worth pointing out that in quantum field theories, the fields aren't actual physical fields like the electric field or magnetic fields but an underlying abstraction from which observables are derived. The matter particles such as electrons and muons are fields as well as the photons pe...
by thoughtfully
Tue Nov 29, 2016 1:57 pm UTC
Forum: Science
Topic: Miscellaneous Science Questions
Replies: 2835
Views: 534507

Re: RELATIVITY QUESTIONS! (and other common queries)

jewish_scientist wrote:
Xanthir wrote:Light is literally an EM wave.

I thought of EM waves as the sum of many photons, and that light refers to photons and/or EM waves.


Okay, what is the minimum number of photons that makes a wave?
The whole point of early QM and the double-slit experiments is that it's wave-like down to individuals.
by thoughtfully
Mon Nov 28, 2016 2:28 pm UTC
Forum: Science
Topic: Miscellaneous Science Questions
Replies: 2835
Views: 534507

Re: RELATIVITY QUESTIONS! (and other common queries)

This should be a bannable offense.
by thoughtfully
Thu Nov 24, 2016 11:45 pm UTC
Forum: Science
Topic: Is entanglement that surprising?
Replies: 27
Views: 4371

Re: Is entanglement that surprising?

I have a pretty straightforward take on this, and it isn't really too unorthodox. Newtonian Physics is a model, and isn't "real". Intuitions based on reality and evolution (also based, more indirectly, on reality) have no expectations of correspondence. No surprises here.
by thoughtfully
Thu Nov 24, 2016 11:28 pm UTC
Forum: Science
Topic: Classifing Organism by Mechanical Structure
Replies: 18
Views: 2626

Re: Classifing Organism by Mechanical Structure

There is a super book on the mechanics of living things titled Cat's Paws and Catapults . You should find it entertaining and edifying, even if it doesn't help with this question. Fun Fact: some clams have muscles that are relaxed in the shortened state, to expend less energy holding their shells cl...
by thoughtfully
Thu Nov 24, 2016 11:19 pm UTC
Forum: Science
Topic: Miscellaneous Science Questions
Replies: 2835
Views: 534507

Re: RELATIVITY QUESTIONS! (and other common queries)

As usual, QM seems to be crashing the party . But at least it fixes those awful singularities and other problems. EDIT Did Maxwell's Equations come from observations that e.g. light didn't travel instantaneously? Maxwell's Equations are a synthesis of relationships (Gauss, Ampere, and Faraday) that ...
by thoughtfully
Mon Sep 05, 2016 2:51 am UTC
Forum: Science
Topic: In 1Billion Years, Earth will become a second Venus.
Replies: 7
Views: 1645

Re: In 1Billion Years, Earth will become a second Venus.

There's a lot of space between uninhabitable and "burning away all traces". The surface of Earth in a billion years will probably be in a condition that doesn't support life "as we know it", but if anyone bothered to come by and have a look, they would probably find some remnants.
by thoughtfully
Sat Jul 23, 2016 4:02 pm UTC
Forum: Coding
Topic: How do you manage Python dependencies?
Replies: 8
Views: 2930

Re: How do you manage Python dependencies?

BeautifulSoup also overloads a lot of operators for its functionality, which can lead to the usual confusions and difficult-to-maintain code. Kinda nice for quick one-offs or interactive interpreter sessions, but beyond that, I would try to stick to html5lib nowadaze.
by thoughtfully
Sun Jun 12, 2016 4:04 pm UTC
Forum: Science
Topic: Alkaline Food
Replies: 26
Views: 4892

Re: Alkaline Food

To be fair, colas are quite acidic, with both carbonic and phosphoric acids. A quick google put the pH around 2.5.
by thoughtfully
Mon May 02, 2016 3:20 pm UTC
Forum: Coding
Topic: How do I become a hardcore/professional software engineer?
Replies: 6
Views: 5245

Re: How do I become a hardcore/professional software engineer?

This is a useful guide to becoming a programmer, but it sounds like you may have some of that covered. http://www.catb.org/esr/faqs/hacker-howto.html I am also something of a "research programmer". I don't get involved in the research or academics of what I'm coding, but I do most of my co...
by thoughtfully
Tue Apr 19, 2016 5:34 pm UTC
Forum: Science
Topic: square base cups
Replies: 24
Views: 4372

Re: square base cups

Even worse are cans that bulge out! They are cool in their transparency, though. The sloshing liquid was visible. Some sort of stiff plastic with an aluminum top.
by thoughtfully
Sat Apr 02, 2016 7:37 pm UTC
Forum: Science
Topic: Can you (passively) heat an object hotter than your source?
Replies: 98
Views: 17881

Re: Can you (passively) heat an object hotter than your source?

I am pretty sure that Thermodynamics requires a perfect absorber to also be a perfect emitter. This looks like a good link, but Hyperphysics isn't coming up for me right now. Ahh, here's a cached page: http://webcache.googleusercontent.com/search?q=cache:tO7d88MAVX0J:hyperphysics.phy-astr.gsu.edu/hb...
by thoughtfully
Fri Mar 18, 2016 8:00 pm UTC
Forum: Coding
Topic: The "IT DOESN'T WORK!" thread
Replies: 1958
Views: 463805

Re: The "IT DOESN'T WORK!" wool

I'm not a database expert, but the advice I usually see is to not put too much logic into the SQL (unless there's a good reason not to, which usually implies you Know What You're Doing and wouldn't be asking), leave that in your programming language. Just stick to SELECT and UPDATE as far as the SQL...
by thoughtfully
Thu Mar 17, 2016 2:26 am UTC
Forum: Science
Topic: Does potential energy have mass?
Replies: 78
Views: 11698

Re: Does potential energy have mass?

In bulk matter, which is what most folk are familiar with, mass is potential energy. Ninety-six to ninety-seven percent comes from the binding forces inside protons and neutrons. The rest mass of elementary particles comes from interactions with the Higgs field, in straightforward ways with the weak...
by thoughtfully
Sun Mar 13, 2016 3:12 am UTC
Forum: Science
Topic: square base cups
Replies: 24
Views: 4372

Re: square base cups

Obviously, triangles are optimal then.

Step two (?)

Profit!
by thoughtfully
Thu Mar 10, 2016 10:57 am UTC
Forum: General
Topic: It has Endginned. (Mod Madness 2016)
Replies: 220
Views: 55069

Re: It Begends. (Mod Madness 2016)

I just want to know how I get assistance from the moderation staff with taking the week off. Will I still receive my usual compensation?
by thoughtfully
Wed Mar 09, 2016 12:10 pm UTC
Forum: Science
Topic: Refraction of different wavelengths in atmosphere
Replies: 5
Views: 2224

Re: Refraction of different wavelengths in atmosphere

Most of the time the sun is more or less overhead. When it's close to the horizon, you notice the refraction.

But yeah, the ionosphere is going to make this problem about more than just refraction.
by thoughtfully
Sun Mar 06, 2016 2:16 pm UTC
Forum: Coding
Topic: IDEs and the death of the command line interface
Replies: 25
Views: 6894

Re: IDEs and the death of the command line interface

I have migrated from Kate to Geany , give it a try. I have been doing a bit of Java/Scala/Android-related stuff, and it's hard to give up the IDE there, but for anything else, a text editor+REPL+browser (for javascript, web apps, etc) and maybe a terminal tab for mathomatic when I need to do a littl...
by thoughtfully
Sat Feb 27, 2016 11:57 pm UTC
Forum: Science
Topic: Quantum Fluctuations questions
Replies: 21
Views: 4256

Re: Quantum Fluctuations questions

This may be a weird notion but could the virtual particles be (a part of) dark matter? The density is extremely low but space is extremely big. Not Dark Matter, but Dark Energy, yes (could be). The predicted energy density and what's observed is off by some hundred orders of magnitude, however. htt...
by thoughtfully
Fri Feb 26, 2016 9:04 pm UTC
Forum: Science
Topic: Quantum Fluctuations questions
Replies: 21
Views: 4256

Re: Quantum Fluctuations questions

Sean Carroll at Caltech posted recently on his blog on this. http://www.preposterousuniverse.com/blog/2016/01/16/quantum-fluctuations/ 1) Empty is not special. Virtual particles happen everywhere. 2) The basic idea behind fluctuations is the Uncertainty Principle. You can't have a unit of space with...
by thoughtfully
Fri Feb 26, 2016 1:07 am UTC
Forum: Science
Topic: How do nutrients and pharmaceuticals decompose?
Replies: 3
Views: 2150

Re: How do nutrients and pharmaceuticals decompose?

There's also volatile compounds that simply evaporate, say with fresh herbs and the like.
by thoughtfully
Fri Feb 19, 2016 7:37 pm UTC
Forum: Science
Topic: is Chicago ever the "front" of the planet?
Replies: 30
Views: 4801

Re: is Chicago ever the "front" of the planet?

The trouble is, space is big. And mostly space. You can draw a line out from the center of the Earth to the point on its surface that intersects with its orbit on the leading side, but that line will pretty much go on forever without hitting anything, except pretty rarely. It does help that the othe...
by thoughtfully
Fri Feb 19, 2016 4:51 am UTC
Forum: Science
Topic: is Chicago ever the "front" of the planet?
Replies: 30
Views: 4801

Re: is Chicago ever the "front" of the planet?

If you want the cold, hard, data, the US Naval Observatory has a software library for calculating positions of celestial bodies.
http://aa.usno.navy.mil/software/novas/novas_info.php
by thoughtfully
Thu Feb 18, 2016 8:54 pm UTC
Forum: Science
Topic: If spin really did represent particles actual spin...
Replies: 18
Views: 3432

Re: If spin really did represent particles actual spin...

It's really difficult to represent fundamental particles as little spheres with a definite radius. Composite particles like protons and neutrons are a bit easier, but not by much. There just isn't a well defined surface to work with.
by thoughtfully
Tue Feb 16, 2016 9:42 pm UTC
Forum: Science
Topic: LIGO Gravity Waves: Questions and Answers
Replies: 49
Views: 6298

Re: LIGO Gravity Waves: Questions and Answers

Another way to look at this is simply as a consequence of the Big Bang happening everywhere, without a preferred location. You look out into the sky, in any direction, and if there's nothing in the way, you can see all the way to the Big Bang. In EM, there's the hot plasma from in early Universe blo...
by thoughtfully
Mon Feb 15, 2016 11:54 pm UTC
Forum: Science
Topic: LIGO Gravity Waves: Questions and Answers
Replies: 49
Views: 6298

Re: LIGO Gravity Waves: Questions and Answers

It's the same idea as with the microwave background from the surface of last scattering, only 380k years or so earlier.

Incidentally, there's also expected to be a neutrino background signal.
by thoughtfully
Tue Feb 09, 2016 10:42 am UTC
Forum: Science
Topic: Wendelstein 7-X
Replies: 43
Views: 6088

Re: Wendelstein 7-X

Fusion reactors are a bit different because the reactant is physically separated from the reactor. There's not very much heat transfer by conduction, as I understand it. Still, there's quite a lot of neutron flux and thermal radiation getting out.
by thoughtfully
Mon Jan 25, 2016 9:14 pm UTC
Forum: Science
Topic: Landing rockets upright is unnecessary?
Replies: 61
Views: 7943

Re: Landing rockets upright is unnecessary?

I like digging up old threads. I'm sure seven won't mind.
by thoughtfully
Fri Jan 22, 2016 8:44 pm UTC
Forum: Science
Topic: electromagnets motors and resistance question
Replies: 3
Views: 1449

Re: electromagnets motors and resistance question

Sometimes the windings themselves provide a significant resistance. They can be very fine, long wires.
by thoughtfully
Thu Jan 21, 2016 9:06 pm UTC
Forum: Science
Topic: Landing rockets upright is unnecessary?
Replies: 61
Views: 7943

Re: Landing rockets upright is unnecessary?

A possibilities come to mind. To land gently enough to prevent damage, you pretty much have to use thrust. parachute landings are a not-so-gentle affair. If you are going to use thrust, your thrust needs to line up with your center of mass, or you will go tumbling around. Landing horizontally also m...
by thoughtfully
Thu Jan 21, 2016 3:09 am UTC
Forum: Science
Topic: Theory of black hole composition
Replies: 50
Views: 5557

Re: Theory of black hole composition

Do you know of published work by physicists on the idea that inflation always occurs in the neighborhood of the event horizon and prevents any infalling objects from reaching it (or reaching the spot where an event horizon would otherwise form, Not exactly what you're looking for, but I recently po...
by thoughtfully
Tue Jan 12, 2016 3:25 pm UTC
Forum: Science
Topic: The Argument from Contingency
Replies: 42
Views: 3763

Re: The Argument from Contingency

It's also possible that our universe was spawned from a (always existing, hence necessary) Multiverse.

But philosophy and language and ideas are meta-things, so one should take care when applying them too broadly to "reality".
by thoughtfully
Thu Jan 07, 2016 10:49 am UTC
Forum: Science
Topic: What's up with avocados?
Replies: 22
Views: 2978

Re: What's up with avocados?

There is a thread concerning chocolate and raptors lurking around somewhere. The main problem is that the prey has to withstand a much higher concentration of toxin than the predator. Alternatively, they could keep it in a pouch attached to their belt, but clever raptors could discard the pouch befo...
by thoughtfully
Wed Jan 06, 2016 5:06 pm UTC
Forum: Science
Topic: What's up with avocados?
Replies: 22
Views: 2978

Re: What's up with avocados?

According to Wikipedia, there's a theory that the target dispersers were extinct megafauna.

Go to advanced search