Comments on: Stupid Google Tricks

Stupid Google Tricks

DevilsAdvocate — Tue, 30 Nov 2004 19:33:20 -0800

Does relativity have any practical significance? In fact, relativity had to be taken into account by the designers of the Global Positioning System. The GPS satellites are affected both by special relativity (since the satellites are moving, clocks aboard them appear to run slower as seen from the ground), and by general relativity (since the satellites are farther away from the mass of the earth, clocks appear to run faster as seen from the ground). The net effect of both is that clocks aboard GPS satellites would gain 38 microseconds per day relative to the ground, if relativistic effects were not corrected for--a figure which can be confirmed by using Google calculator.

By: DevilsAdvocate

DevilsAdvocate — Tue, 30 Nov 2004 19:33:57 -0800

If you think spelling everything out in that last link was silly, you might prefer this one.

By: vacapinta

vacapinta — Tue, 30 Nov 2004 19:47:24 -0800

Nice! thanks. It's interesting to think that if GPS had arrived before the theory of relativity, we'd be worrying about the really strange time lag demonstrated by satellites. The offhand (and true) explanation that they are traveling through Time at a different rate than we are still sounds like something out of science fiction.

By: odinsdream

odinsdream — Tue, 30 Nov 2004 20:16:10 -0800

I really like that little google trick. I wonder if it has a nesting limitation?

By: homodigitalis

homodigitalis — Tue, 30 Nov 2004 20:46:04 -0800

This can only be a hoax - as everyone know the earth is flat, space and time are absolute - and never relativ - unless you watch soap operas and love creationism.

By: reflection

reflection — Tue, 30 Nov 2004 20:49:44 -0800

RE: Nesting limitation. apparently not. However, as you will find out if you try to double up on that "equation," Google does have a character limit as to what you can send their search engine before they default with a, "Bad Request: Your client has issued a malformed or illegal request."

By: Ayn Marx

Ayn Marx — Tue, 30 Nov 2004 20:53:58 -0800

This can only be a hoax Agreed. Remember: relativity is a *theory.* Like gravity.

By: reflection

reflection — Tue, 30 Nov 2004 20:57:42 -0800

I should add, the next limitation will be their 32 bit processors. As an example, try this link, and take note of the number at the end of the URL. Then try this link. You will notice it peaks at 2,147,483,647. Don't be deceived by that number on the front page (8,058,044,651), or by this search returning 8,000,000,000 results.

By: weapons-grade pandemonium

weapons-grade pandemonium — Tue, 30 Nov 2004 21:10:22 -0800

And were it not for this incredibly sophisticated technology, precision bombing, like we saw in Fallujah, would not be possible. It's saving tens of thousands of innocent lives.

By: weapons-grade pandemonium

weapons-grade pandemonium — Tue, 30 Nov 2004 21:12:33 -0800

Einstein was right--everything is relative.

By: DevilsAdvocate

DevilsAdvocate — Tue, 30 Nov 2004 21:43:21 -0800

Meanwhile, if you were riding aboard a GPS satellite, a clock on the ground would appear to lose 53 microseconds per day. An observer on the ground and an observer on the satellite "agree" that the clock on the ground runs slower due to gravitational time dilation, but the time dilation due to velocity is, for each observer, perceived as making the other clock run slower. The two effects partially cancel for the observer on the ground looking at the satellite (the satellite clock runs faster due to gravity and slower due to velocity), but act with the same sign for the observer on the satellite looking at the ground (the clock on the ground runs slower due to gravity, and slower due to velocity). everything is relative Not quite...the speed of light in a vacuum, among other things, is constant.

By: weapons-grade pandemonium

weapons-grade pandemonium — Tue, 30 Nov 2004 21:51:54 -0800

How about irony?

By: breath

breath — Tue, 30 Nov 2004 22:14:50 -0800

Not quite...the speed of light in a vacuum, among other things, is constant. Maybe not. I believe I read another article about how a new super-accurate clock was accurate enough to witness the slew of the cosmological constants over a period of a few years.

By: jefbla

jefbla — Tue, 30 Nov 2004 22:25:43 -0800

Shit, it's late at night and I'm drunk. But, I appreciate this post. I will check your calculation in the morning. Thank you, this is interesting. Nighty night.

By: jenovus

jenovus — Tue, 30 Nov 2004 22:56:12 -0800

Special relativity by itself is enough to give you the permanent kind of headache. But I love it anyway. C'mere, you big, crazy universe, you! HUGS

By: weapons-grade pandemonium

weapons-grade pandemonium — Tue, 30 Nov 2004 23:19:39 -0800

Nah! Relativity is relatively easy to understand.

By: jenovus

jenovus — Tue, 30 Nov 2004 23:22:12 -0800

Nice. I don't want to use a word too huge, but nice. I am in your debt.

By: No Explanation

No Explanation — Tue, 30 Nov 2004 23:35:50 -0800

MeFi University.

By: fvw

fvw — Wed, 01 Dec 2004 01:10:26 -0800

No tinyurl's please! Google (and MeFi) are likely to be around long after tinyurl is gone, and people reading this in the archive won't be able to get the links. And anyway, you're putting the URLs in HTML links, so nobody's going to be bothered by the links being rather long (but it is nice to be able to mouseover links, even if they don't fit in your status bar in their entirety). DevilsAdvocate's first link and his second. Apart from that, excellent post!

By: fatllama

fatllama — Wed, 01 Dec 2004 01:30:27 -0800

Nice, Devil'sAdvocate. But I think this guy has the right idea.

By: andrew cooke

andrew cooke — Wed, 01 Dec 2004 02:18:31 -0800

Agreed. Remember: relativity is a *theory.* Like gravity. i'd be careful with saying things like that. i guess you're trying to make a comparison with evolution, using the assumption that gravity is obviously correct. in fact, classical gravity was superceded by general relativity, so in this context, you're arguing against yourself. and maybe it's just me, but i'd prefer scientific debates to be won by argument, rather that trite slogans that snigger at the "the other side". isn't the whole point that there is a correct answer, whatever the soundbites are?

By: buddhanarchist

buddhanarchist — Wed, 01 Dec 2004 04:54:31 -0800

the speed of light in a vaccum is constant--- thats why everything is relative.

By: bashos_frog

bashos_frog — Wed, 01 Dec 2004 07:09:49 -0800

...using the assumption that gravity is obviously correct. in fact, classical gravity was superceded by general relativity... The effects of gravity are readily observable, regardless of the current theory to explain their cause. Those arguing against evolution deny not only the cause, but the effects as well. Not to mention, that a theory like intelligent grappling would not gain much traction in a public debate.

By: Capn

Capn — Wed, 01 Dec 2004 08:09:23 -0800

Does relativity have practical significance? Pah! IC designers have to worry about quantum mechanical effects

By: weapons-grade pandemonium

weapons-grade pandemonium — Wed, 01 Dec 2004 10:41:23 -0800

the speed of light in a vaccum is constant ...which means you can't double c in a vacuum.

By: DevilsAdvocate

DevilsAdvocate — Thu, 02 Dec 2004 13:51:48 -0800

fvw: point taken. I didn't want to bog down the thread with this earlier, but now that it's more or less died down, here's all the gory details on the math I used to build up that expression: G = gravitational constant m = mass of earth c = speed of light t = orbital period = 1/2 sidereal day A sidereal day is the time it takes for stars to reappear in the same position as seen from earth, about 4 minutes shorter than a standard (solar) day. r_E = radius of earth The really neat thing about Google calculator is that you don't have to actually look these values up or worry about units; Google takes care of all that. Oh, and this: p is a pi; sorry that it looks a little funky in the default font. r_s = distance of satellite from the center of the earth = [Gmt²/(2p)²]^1/3 v = velocity of satellite = 2pr_s/t = (2pGm/t)^1/3 Convention: Throughout this, I'll define time dilation factors (f) to be the time which appears to elapse on a clock in a different frame from an observer, divided by the time which elapses as measured by a clock with the observer. Thus, f>1 indicates the distant clock appears to run faster than ours, while f<1 indicates that it appears to run slower. Gravitational time dilation: To an observer an infinite distance from a mass, a clock near the mass appears to run slow: f_8->r = 1 - (Gm/c²r) Thus, an observer at an infinite distance from earth sees a clock at the surface of the earth run with f_8->E = 1 - (Gm/c²r_E) While for the same infinite observer, the clock aboard the GPS satellite runs with: f_8->s = 1 - (Gm/c²r_s) To an observer on earth, therefore, the clock aboard the GPS runs faster due to gravitational time dilation with: f_E->s = f_8->s/f_8->E Velocity time dilation There is also a time dilation effect due to the fact that the satellite is moving relative to the earth; this factor is given by: f_v = [1-(v/c)²]^1/2 (This is constant for an observer at the poles; for anyone else, the velocity will vary over the course of a day due to rotation of the earth, but to a first-order approximation the effect of the rotation will cancel out over the course of a day.) The clock aboard the satellite appears to run slower due to velocity time dilation, so this is less than 1. Finishing up The overall factor for how the clock aboard the satellite appears to run from the ground is the product of the gravitational and velocity factors: f = f_vf_E->s The time which appears to elapse on a clock on the satellite for a given time at the surface of the earth is given by T_s = fT_E Set T_E = 1 day, and ever so slightly more than one day elapses on the satellite. Subtract 1 day from T_s to find just how much more.

By: DevilsAdvocate

DevilsAdvocate — Thu, 02 Dec 2004 13:53:35 -0800

Gah, all my π's got changed to p's between the preview and the post. Sorry about that.