Search found 154 matches

by taby
Fri Feb 01, 2008 4:22 pm UTC
Forum: Science
Topic: Dark Matter? Or is it time slowing down?
Replies: 8
Views: 1642

Re: Dark Matter? Or is it time slowing down?

Just to be clear... it is dark energy, and not dark matter, that is currently postulated to be behind cosmic repulsion.
by taby
Tue Jan 29, 2008 6:47 pm UTC
Forum: Science
Topic: Artificial gravity through superconductors
Replies: 19
Views: 2369

Re: Artificial gravity through superconductors

Minerva wrote:What on Earth does an electric current have to do with gravity anyway? How do you expect it to create any gravity like force, exactly?


http://en.wikipedia.org/wiki/Reissner-Nordstrom_metric
http://en.wikipedia.org/wiki/Kerr-Newman_black_hole
by taby
Sat Jan 26, 2008 3:23 am UTC
Forum: Science
Topic: Pseudo science, and science funding
Replies: 91
Views: 9060

Re: Pseudo science, and science funding

First, I want to call taby out on his statement that Popper's philosophy of science is close to what science actually is. It isn't, it's not even close. While science does an amount of conjecture and refutation, that is nowhere close to what normal science is. It is beyond being an oversimplificati...
by taby
Sat Jan 26, 2008 3:16 am UTC
Forum: Science
Topic: Artificial gravity through superconductors
Replies: 19
Views: 2369

Re: Artificial gravity through superconductors

What is the most dense configuration of matter short of a neutron star? I know iridium and osmium are trading #1 for most dense element, but is there a more dense configuration of matter that could have a much higher bonding energy between atoms or somesuch that would put it even higher? Packing ne...
by taby
Fri Jan 25, 2008 9:31 pm UTC
Forum: Science
Topic: Lab Life: The Scientist's Coffee Corner
Replies: 67
Views: 7501

Re: Lab Life: The Scientist's Coffee Corner

lesliesage wrote:Do they apply to real angiogenesis, or is it more pure physics or chemistry?


As far as I know, DLA is used mostly to model chemical deposits. This might be interesting: http://www.andylomas.com/aggregationImages.html
by taby
Fri Jan 25, 2008 7:10 pm UTC
Forum: Science
Topic: Artificial gravity through superconductors
Replies: 19
Views: 2369

Re: Artificial gravity through superconductors

Minerva wrote:What on Earth does an electric current have to do with gravity anyway? How do you expect it to create any gravity like force, exactly?


Edit:
http://en.wikipedia.org/wiki/Reissner-Nordstrom_metric
http://en.wikipedia.org/wiki/Kerr-Newman_black_hole
by taby
Fri Jan 25, 2008 5:56 pm UTC
Forum: Science
Topic: Pseudo science, and science funding
Replies: 91
Views: 9060

Re: Pseudo science, and science funding

First, I want to call taby out on his statement that Popper's philosophy of science is close to what science actually is. It isn't, it's not even close. While science does an amount of conjecture and refutation, that is nowhere close to what normal science is. It is beyond being an oversimplificati...
by taby
Fri Jan 25, 2008 4:39 pm UTC
Forum: Science
Topic: Learning General Relativity
Replies: 9
Views: 1686

Re: Learning General Relativity

As mentioned above, differential geometry can be a nightmare to get into, but it is absolutely necessary to get a full grasp of what's happening in GR. I started learning GR using Misner, Thorne, Wheeler's Gravitation book, but it was way too intense. I then got Schutz's A First Course in General Re...
by taby
Sat Jan 19, 2008 11:20 pm UTC
Forum: Computer Science
Topic: I have a question about the future of cryptography.
Replies: 43
Views: 9010

Re: I have a question about the future of cryptography.

That said, I repeat again that for how RSA is used in practice this point is moot. Because the set of equally likely conversations in the key exchange are very large, and the encryption algorithm changes for each conversation. Imagine that I have generated a random string, which when using your pub...
by taby
Fri Jan 18, 2008 9:20 pm UTC
Forum: Computer Science
Topic: I have a question about the future of cryptography.
Replies: 43
Views: 9010

Re: I have a question about the future of cryptography.

With all this said, the overall security is not entirely based on the key length/algorithm alone. Encoding a certain plaintext message with a certain RSA key will always produce the same ciphertext message. That in itself is as insecure as the Caesar Cipher (the kind you used in grade 2 to write not...
by taby
Fri Jan 18, 2008 4:18 pm UTC
Forum: Computer Science
Topic: Neural Networks question
Replies: 2
Views: 2551

Re: Neural Networks question

From what I can guess, you are correct. They seem to be looking for the equation that an input value goes through in the two intermediate layers in order to end up in the single output node?
by taby
Thu Jan 17, 2008 7:14 pm UTC
Forum: Science
Topic: Lab Life: The Scientist's Coffee Corner
Replies: 67
Views: 7501

Re: Lab Life: The Scientist's Coffee Corner

I don't work in a scientific environment (unless one counts computer science as a hard science), but that image you posted is really neat. My question is: Have you done any research into Diffusion Limited Aggregation? Paul Bourke has a neat page on it, showing how they can form a system of arterial ...
by taby
Thu Jan 17, 2008 7:09 pm UTC
Forum: Science
Topic: Parallel Universes
Replies: 35
Views: 6097

Re: Parallel Universes

The book The Fabric of Reality by David Deutsch might be of some interest to those looking into parallel universes. He talks about the inferred existence of "shadow" photons as being a source of disturbance in the quantum double-slit experiment, then goes further by extending that to "...
by taby
Mon Jan 14, 2008 11:00 pm UTC
Forum: Science
Topic: Help me think up crazy hard SF technology ideas
Replies: 74
Views: 6714

Re: Help me think up crazy hard SF technology ideas

Please, don't perpetuate Ray Kurzweil's garbage. He's a modern day Nostradamus, constantly refining and fixing his predictions to fit with new knowledge (the only scientific aspect he possesses) but retaining loads of garbage (like his predictions about what our CPUs and memory will be based upon i...
by taby
Mon Jan 14, 2008 3:41 pm UTC
Forum: Science
Topic: Time to reach the singularity once past the event horizon.
Replies: 2
Views: 1370

Re: Time to reach the singularity once past the event horizon.

According to these notes...

http://www.astro.uu.se/~nisse/courses/k ... es/ln3.pdf

... the proper time to travel from the event horizon to the physical singularity is 2Rs/c (which is equal to 4GM/c3).

You might get a more thorough response on physicsforums.com.
by taby
Sun Jan 13, 2008 4:59 pm UTC
Forum: Coding
Topic: Bool pointer to an array help C++
Replies: 29
Views: 5850

Re: Bool pointer to an array help C++

Thank you all for elaborating. This is very informative. I do like Scott Meyers' work a lot. :) Hangar -- Iterators were designed to replace direct pointer addressing for STL containers. The only time I will ever use pointer addressing is when I have to use an int* into a C function (or whatever typ...
by taby
Sun Jan 13, 2008 4:00 am UTC
Forum: Science
Topic: Help me think up crazy hard SF technology ideas
Replies: 74
Views: 6714

Re: Help me think up crazy hard SF technology ideas

Ok, imagine it's say 10,000 years from now, and humanity is still around. We didn't get knocked into any sort of dark ages where any real scientific knowledge was lost, and we have constantly progressing foreward in technological development, to at least some degree. What kind of stuff might we hav...
by taby
Sun Jan 13, 2008 3:11 am UTC
Forum: Coding
Topic: Bool pointer to an array help C++
Replies: 29
Views: 5850

Re: Bool pointer to an array help C++

vector<bool> is... strange, and has some problems. Can you elaborate? I've used std::vector<bool> many times, without issue (ex: they work like a vector should, from my experience). In fact, my fractal app relies on them for about a dozen different things (http://cpp.criticaldamage.com/index.php/Ju...
by taby
Sat Jan 12, 2008 6:55 pm UTC
Forum: Coding
Topic: Bool pointer to an array help C++
Replies: 29
Views: 5850

Re: Bool pointer to an array help C++

One other way to go is STL, which is an official part of C++ itself, so it should work with any modern compiler automatically. #include <vector> using std::vector; ... vector<bool> lala(8*8); lala[0] = false; The vector automatically frees this memory when it goes out of scope, so no manual calls to...
by taby
Thu Jan 10, 2008 11:29 pm UTC
Forum: Science
Topic: Banana Stacking
Replies: 10
Views: 1898

Re: Banana Stacking

Factors affecting resistance of banana fruit to compression and impact bruising
Nigel H Banks, Marilyn Joseph

Shows how temperature moderates bruising, and other things.
by taby
Thu Jan 10, 2008 4:48 pm UTC
Forum: Science
Topic: Pseudo science, and science funding
Replies: 91
Views: 9060

Re: Pseudo science

No but being unwelcome does not make a theory pseudo scientific. Being proposed by someone outside the field with no recognized credentials does. I can agree with this. This is why I'm becoming more and more hesitant to pass around ideas until they've been given some kind of positive review. Of cou...
by taby
Thu Jan 10, 2008 4:45 pm UTC
Forum: Science
Topic: Pseudo science, and science funding
Replies: 91
Views: 9060

Re: Pseudo science

I was under the impression that Cooperstock's and Tieu's (I have briefly met Tieu) results were quite controversial and produced a non physical result. From what I understand, it was shown that their model was emulating a singular (perfectly flat) disc. http://arxiv.org/abs/astro-ph/0508377 This pa...
by taby
Wed Jan 09, 2008 11:49 pm UTC
Forum: Science
Topic: Pseudo science, and science funding
Replies: 91
Views: 9060

Re: Pseudo science

So, speaking of pseudoscience... I would like to share a small manuscript that I wrote (attached as PDF). I am not a physicist, but a graphics programmer. The manuscript was recently reviewed as being too abrupt, lacking in full explanation, almost terse, but interesting. It is currently under revie...
by taby
Tue Jan 08, 2008 11:05 am UTC
Forum: Science
Topic: Pseudo science, and science funding
Replies: 91
Views: 9060

Re: Pseudo science

In case it comes up, let me emphasize that while I do think that Lisi’s paper has enough interesting about it that it is worth working on the open issues, I also think that the press coverage was premature and told that to the journalists who contacted me. The “Fabulous…” quote by me was taken out ...
by taby
Tue Jan 08, 2008 10:25 am UTC
Forum: Science
Topic: Pseudo science, and science funding
Replies: 91
Views: 9060

Re: Pseudo science

Of course, Lee Smolin gave peer-review a huge kick between the legs when he went to the press about Lisi's work, before it was peer-reviewed. Motl, Hossenfelder, and Distler then showed that even after a brief glimpse that there are major issues (ex: battery slot not included, let alone batteries)....
by taby
Mon Jan 07, 2008 11:30 pm UTC
Forum: Science
Topic: Pseudo science, and science funding
Replies: 91
Views: 9060

Re: Pseudo science

Ohh, no, it's the opposite. [They] think [that] they invented the scientific method. Popper was a philosopher: http://en.wikipedia.org/wiki/Karl_Popper The cute thing to do is call oneself a 'Popperazzi' (hounding those who do not follow the modern scientific method). http://www.thetroublewithphysi...
by taby
Mon Jan 07, 2008 8:54 pm UTC
Forum: Science
Topic: Momentum Under Water
Replies: 2
Views: 988

Re: Momentum Under Water

MarshyMarsh wrote:Can someone please explain to me how to work out the momentum of an object in a viscous liquid (water for example). Thanks for any help.



It may help to view viscosity as merely the diffusion of momentum -- ex: the travelling body's momentum does not get diffused in an inviscid fluid.
by taby
Mon Jan 07, 2008 8:34 pm UTC
Forum: Science
Topic: Pseudo science, and science funding
Replies: 91
Views: 9060

Re: Pseudo science

Ohh, no, it's the opposite. [They] think [that] they invented the scientific method. Popper was a philosopher: http://en.wikipedia.org/wiki/Karl_Popper The cute thing to do is call oneself a 'Popperazzi' (hounding those who do not follow the modern scientific method). http://www.thetroublewithphysi...
by taby
Mon Jan 07, 2008 8:29 pm UTC
Forum: Science
Topic: Pseudo science, and science funding
Replies: 91
Views: 9060

Re: Pseudo science

I am at odds with myself on this one. On page 2 the author states that mass increases with velocity. Relativistic mass is a very old concept, and was abandoned for the most part a long time ago. It is the kinetic energy which increases with velocity. The inertial mass remains the same. For this, I h...
by taby
Fri Nov 02, 2007 5:26 pm UTC
Forum: Science
Topic: Units in the Einstein Field Equations
Replies: 4
Views: 1421

Re: Units in the Einstein Field Equations

Maybe this is a better way to ask...

I've found that the following units apply:
Energy, J = kg*m^2/s^2
Speed of light, c = m/s

So:
Momentum, E/c = kg*m/s
Mass, E/c^2 = kg
E/c^3 = kg*s/m
E/c^4 = kg*s^2/m^2

Spacetime curvature, 8*pi*E / c^4 = SR*kg*s^2/m^2

Are there any major flaws in this logic?
by taby
Fri Nov 02, 2007 3:06 pm UTC
Forum: General
Topic: Who the dickens are you?
Replies: 10922
Views: 2380543

Re: POST HERE FIRST - INTRO THREAD THE THIRD

Hi, my name is Shawn. I am from Regina, Canada. I like cats and relativity and OpenGL.

I started reading XKCD about a year ago I think, and I love it because of the relativity jokes.
by taby
Thu Nov 01, 2007 8:50 pm UTC
Forum: Science
Topic: Units in the Einstein Field Equations
Replies: 4
Views: 1421

Units in the Einstein Field Equations

I've seen the Einstein Field Equations defined as: G_uv = k*T_uv, k = 8*pi / c^4. Of what units are k considered to be? Is it steradians / 4-volume? Of what units would G_00 be? T_00 = E, G_00 = 8*pi*E / c^4. What about G_01, in the case of a photon travelling along the x dimension? T_01 = E / c, G_...

Go to advanced search