1125: "Objects In Mirror"

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orthogon
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Re: 1125: "Objects In Mirror"

Postby orthogon » Thu Oct 25, 2012 12:33 pm UTC

So if you approached a red traffic light fast enough, it would appear green. This is a glaring error in the design of traffic lights and should be rectified at once with a new system of colours.
xtifr wrote:... and orthogon merely sounds undecided.

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Re: 1125: "Objects In Mirror"

Postby BrianB » Thu Oct 25, 2012 12:47 pm UTC

speising wrote:i have trouble believing that russians would post an english joke in their vehicle.


I really don't think you were supposed to believe it. Funny and believable are two different sets (though they sometimes overlap).

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Re: 1125: "Objects In Mirror"

Postby AvatarIII » Thu Oct 25, 2012 2:09 pm UTC

orthogon wrote:So if you approached a red traffic light fast enough, it would appear green. This is a glaring error in the design of traffic lights and should be rectified at once with a new system of colours.


was that a reference to "What If? #14 Short Answer Section"?

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Re: 1125: "Objects In Mirror"

Postby jpers36 » Thu Oct 25, 2012 2:27 pm UTC

Pfhorrest wrote:This comic reminds me of a shot I've always found funny in Jurrasic Park, where the T-rex, whose gaping maw is visible in the passenger-side mirror, is apparently closer than it appears, according to said mirror.

If it were also bluer than it appeared, that would bring all new meaning to Malcolm's urging that they "must go faster. must. go. faster!"


Or ...

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Re: 1125: "Objects In Mirror"

Postby Someguy945 » Thu Oct 25, 2012 3:59 pm UTC

Though I doubt Randall's interested in my opinion, this comic would be better with no caption. Randall, please don't get "Close To Home" syndrome!

(Close To Home = wannabe Far Side that usually has an unnecessary caption repeating the same joke that was in the comic)

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Re: 1125: "Objects In Mirror"

Postby mfb » Thu Oct 25, 2012 4:19 pm UTC

Mirrors in object are closer than they appear.

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Re: 1125: "Objects In Mirror"

Postby bmonk » Thu Oct 25, 2012 8:12 pm UTC

speising wrote:i have trouble believing that russians would post an english joke in their vehicle.

Maybe it was posted by the Americans onboard?
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Re: 1125: "Objects In Mirror"

Postby dudiobugtron » Fri Oct 26, 2012 12:29 am UTC

AvatarIII wrote:a thought: if the stationary object is violet, surely it would be red-shifted TOWARDS blueness, and would actually appear bluer than it really is.

This astute observation definitely deserves some lauding. Consider it lauded.
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Re: 1125: "Objects In Mirror"

Postby orthogon » Fri Oct 26, 2012 7:57 am UTC

AvatarIII wrote:
orthogon wrote:So if you approached a red traffic light fast enough, it would appear green. This is a glaring error in the design of traffic lights and should be rectified at once with a new system of colours.


was that a reference to "What If? #14 Short Answer Section"?


D'oh. No, it wasn't - I fondly imagined I was being original. I was never very fastidious about literature searches...
xtifr wrote:... and orthogon merely sounds undecided.

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Re: 1125: "Objects In Mirror"

Postby AvatarIII » Fri Oct 26, 2012 8:04 am UTC

dudiobugtron wrote:
AvatarIII wrote:a thought: if the stationary object is violet, surely it would be red-shifted TOWARDS blueness, and would actually appear bluer than it really is.

This astute observation definitely deserves some lauding. Consider it lauded.


8-)

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Re: 1125: "Objects In Mirror"

Postby Rotherian » Fri Oct 26, 2012 1:39 pm UTC

speising wrote:i have trouble believing that russians would post an english joke in their vehicle.


Because, of course, there are no multilingual Russians. :roll:
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Re: 1125: "Objects In Mirror"

Postby Fire Brns » Fri Oct 26, 2012 3:37 pm UTC

ijuin wrote:There was an incident where a Soyuz capsule collided with the Russian space station at low relative speed while attempting to dock. After that, they posted a notice in the cockpits reminding the pilots that "Objects in Mir are closer than they appear." :D

I immediately thought of Soyuz 25.
From Wiki: "The failure led to a new rule whereby every crew had to have at least one person aboard who had previously flown in space"
You mean you were shooting people into space without experienced personnel!?
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Re: 1125: "Objects In Mirror"

Postby Moose Anus » Fri Oct 26, 2012 5:31 pm UTC

Rotherian wrote:
speising wrote:i have trouble believing that russians would post an english joke in their vehicle.


Because, of course, there are no multilingual Russians. :roll:
Of course there are. But there are no multilingual space Russians.
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Re: 1125: "Objects In Mirror"

Postby speising » Fri Oct 26, 2012 7:36 pm UTC

Moose Anus wrote:
Rotherian wrote:
speising wrote:i have trouble believing that russians would post an english joke in their vehicle.


Because, of course, there are no multilingual Russians. :roll:
Of course there are. But there are no multilingual space Russians.


that may be. there may also exist american astronauts who speak russian. but you would think it highly unlikely that they'd post russian puns in a space shuttle (when they still flew), wouldn't you?

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Re: 1125: "Objects In Mirror"

Postby steve waterman » Fri Oct 26, 2012 7:51 pm UTC

This is just the wiki internet article, and as such, may not be 100 percent reliable as a source.

Hubble constant

The law is often expressed by the equation v = H0D, with H0 the constant of proportionality (the Hubble constant) between the "proper distance" D to a galaxy (which can change over time, unlike the comoving distance) and its velocity v (i.e. the derivative of proper distance with respect to cosmological time coordinate; see Uses of the proper distance for some discussion of the subtleties of this definition of 'velocity'). The SI unit of H0 is s−1 but it is most frequently quoted in (km/s)/Mpc, thus giving the speed in km/s of a galaxy 1 megaparsec (3.09×1019 km) away. The reciprocal of H0 is the Hubble time.

As of 3rd Oct 2012 the Hubble constant, as measured by NASA's Spitzer Telescope and reported in Science Daily, is 74.3 ± 2.1 (km/s)/Mpc



Conceptually speaking, I am quite curious about this Hubble constant.

I must obviously be missing some key points here.

Can someone please help to explain why the Hubble constant is not a type of human/earth-centric logic?


thus giving the speed in km/s of a galaxy 1 megaparsec (3.09×1019 km) away as 74.3 ± 2.1 (km/s)/Mpc

So, galaxies at distance x from earth are quantized with the same rate of expansion as each other?

So, that would make the Earth the mathematical CENTER for all these calculations, and not the site of the "big bang"?

As a thought experiment, what if we draw a line from the site of the "big bang" to a signal receiver along the same line to the Earth and a receiver beyond Earth.

Locations along that line would all maintain their separation distances from one another in an expanding universe over time.

Any signal receiver pointed towards the direction of the "big bang" site must record light as red-shifted
since the signal receiver is moving away from the stationary point of a light signal transmitted at rate c.

In an expanding universe ANY receiver pointed outwardly ...so, getting a transmission from past the earth along that line
must record blue-shifted light, due to the Earth moving towards the stationary point of the light signal transmitted at rate c.
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Re: 1125: "Objects In Mirror"

Postby speising » Fri Oct 26, 2012 8:00 pm UTC

steve, c is not a rate, but that's beside the point.

imagine our universe as the surface of a balloon. if that balloon gets blown up, evry point on the surface receedes from every other point. in this 2D universe, there is no center.
similarily, the earth is not the center of our real universe, butr everything receedes from it.
the big bang did not occur at any specific point in our universe. or rather, ir occurred everywhere.

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Re: 1125: "Objects In Mirror"

Postby Rotherian » Fri Oct 26, 2012 8:03 pm UTC

speising wrote:
Moose Anus wrote:
Rotherian wrote:
speising wrote:i have trouble believing that russians would post an english joke in their vehicle.


Because, of course, there are no multilingual Russians. :roll:
Of course there are. But there are no multilingual space Russians.


that may be. there may also exist american astronauts who speak russian. but you would think it highly unlikely that they'd post russian puns in a space shuttle (when they still flew), wouldn't you?


It might be unlikely, but some multilingual people actually like making jokes based on things from other cultures.
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Re: 1125: "Objects In Mirror"

Postby mathmannix » Fri Oct 26, 2012 9:08 pm UTC

Guys, please don't turn this into another "Pressures" thread...
I hear velociraptor tastes like chicken.

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Re: 1125: "Objects In Mirror"

Postby bmonk » Fri Oct 26, 2012 9:22 pm UTC

speising wrote:steve, c is not a rate, but that's beside the point.

imagine our universe as the surface of a balloon. if that balloon gets blown up, every point on the surface recedes from every other point. in this 2D universe, there is no center.
similarly, the earth is not the center of our real universe, but everything recedes from it.
the big bang did not occur at any specific point in our universe. or rather, it occurred everywhere.


Yes. In a way, every point appears to be the center--because at the moment the bang occurred, every point WAS at the center.
Having become a Wizard on n.p. 2183, the Yellow Piggy retroactively appointed his honorable self a Temporal Wizardly Piggy on n.p.1488, not to be effective until n.p. 2183, thereby avoiding a partial temporal paradox. Since he couldn't afford two philosophical PhDs to rule on the title.

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Re: 1125: "Objects In Mirror"

Postby jjcote » Fri Oct 26, 2012 10:53 pm UTC

If you put the car in reverse, does the message on the mirror change?

(As others have noted about the Big Bang, objects are not moving through space. Everything is actually stationary, it's just that the space between things is getting bigger, so they're getting further apart, and that make it look like everything is moving.)

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Re: 1125: "Objects In Mirror"

Postby ijuin » Sun Oct 28, 2012 6:56 am UTC

Fire Brns wrote:
ijuin wrote:There was an incident where a Soyuz capsule collided with the Russian space station at low relative speed while attempting to dock. After that, they posted a notice in the cockpits reminding the pilots that "Objects in Mir are closer than they appear." :D

I immediately thought of Soyuz 25.
From Wiki: "The failure led to a new rule whereby every crew had to have at least one person aboard who had previously flown in space"
You mean you were shooting people into space without experienced personnel!?

Well, if you go back to before Soyuz started, there WERE no experienced personnel unless you wanted to fly the same six Vostok pilots over and over. By Soyuz 25 though, there were at least three dozen people who had flown. The big issue here is that at that time, the Soyuz model in use was only rated to carry two people (After the crew of Soyuz 11 died, it was mandatory for all crew to wear their suits during launch, docking, and reentry, but the only way that three people could fit into the capsule was WITHOUT the suits, so the crew was reduced to two. The Soyuz-T model, introduced in 1980, had a larger cabin that could again accommodate three suited crew). Since there were only two crew aboard each Soyuz, the requirement to have one veteran on each mission meant that only one rookie could fly on each mission.

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Re: 1125: "Objects In Mirror"

Postby webgiant » Sun Oct 28, 2012 10:22 pm UTC

AvatarIII wrote:Hubble was American, so cars would be overtaking on the other side anyway.

If Hubble was American, then cars would be overtaking on BOTH sides. Even when the road only has your lane and the opposite lane, because there's usually a wide shoulder. Americans are crazy drivers. I speak from personal experience, and being an American.

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Re: 1125: "Objects In Mirror"

Postby orthogon » Mon Oct 29, 2012 2:26 pm UTC

orthogon wrote:
AvatarIII wrote:
orthogon wrote:So if you approached a red traffic light fast enough, it would appear green. This is a glaring error in the design of traffic lights and should be rectified at once with a new system of colours.


was that a reference to "What If? #14 Short Answer Section"?


D'oh. No, it wasn't - I fondly imagined I was being original. I was never very fastidious about literature searches...


In an attempt to redeem myself, I have taken the liberty of calculating the stopping distance. According to Amanda1801's formula, the total stopping distance in feet (including thinking time) is v(v/20+1) where v is the speed in mph. Hence at a speed of c/6=112x10^6mph, the stopping distance is 6.26x10^14ft = 1.9x10^14m. (Actually the car only travels a negligible 34,000km, barely one lap of the Earth, during the thinking time).
xtifr wrote:... and orthogon merely sounds undecided.

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Re: 1125: "Objects In Mirror"

Postby GingerKarma » Tue Oct 30, 2012 11:15 am UTC

If you move toward something, regardless of its motion, it's redshifted.
If you move away from something, regardless of its motion, it's blueshifted.
You're moving away from the objects in your rear-view mirror, therefore they're blueshifted.
If the object is blueshifted, it appears bluer than it is.
If an object appears bluer than it is, it's redder than it appears.
Objects in the rear-view mirror are redder than they appear.

He got it backwards. The guy's allowed to make a mistake.

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Re: 1125: "Objects In Mirror"

Postby phlip » Tue Oct 30, 2012 12:51 pm UTC

GingerKarma wrote:If you move toward something, regardless of its motion, it's redshifted.
If you move away from something, regardless of its motion, it's blueshifted.

(a) That's the wrong way around - things you're moving towards are blueshifted.
(b) It's not "regardless of its motion"... movement is relative, after all. You moving at a certain speed towards a stationary object is the same as that object moving at that speed towards you. Essentially, things are blueshifted if the distance between you and it is decreasing, and redshifted if the distance between you and it is increasing.

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enum ಠ_ಠ {°□°╰=1, °Д°╰, ಠ益ಠ╰};
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Re: 1125: "Objects In Mirror"

Postby GingerKarma » Tue Oct 30, 2012 10:49 pm UTC

phlip wrote:
GingerKarma wrote:If you move toward something, regardless of its motion, it's redshifted.
If you move away from something, regardless of its motion, it's blueshifted.

(a) That's the wrong way around - things you're moving towards are blueshifted.
(b) It's not "regardless of its motion"... movement is relative, after all. You moving at a certain speed towards a stationary object is the same as that object moving at that speed towards you. Essentially, things are blueshifted if the distance between you and it is decreasing, and redshifted if the distance between you and it is increasing.


Aaaand... you're absolutely right. Mea culpa and thanks for the correction. I guess I'm the one who got it backwards.

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Re: 1125: "Objects In Mirror"

Postby AlexanderRM » Wed Oct 31, 2012 11:07 pm UTC

AvatarIII wrote:
dangerfan wrote:
AvatarIII wrote:Hubble was American, so cars would be overtaking on the other side anyway.


Not if you live in Massachusetts...


Is that a fact or a joke?


It's a joke. Drivers in Massachusetts are famous for all driving in the left lane (which is supposed to be the passing lane but people often think of as the "fast lane") which results in people passing each other in the right lane. Also things like speeding up to pass another car because they activated their turn signal (this is one I have personally encountered at one point), and just in general driving pretty fast.

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Re: 1125: "Objects In Mirror"

Postby Pfhorrest » Thu Nov 01, 2012 12:12 am UTC

AlexanderRM wrote:Drivers in Massachusetts are famous for all driving in the left lane (which is supposed to be the passing lane but people often think of as the "fast lane")

This actually varies by state. In California, it's perfectly legal to cruise along in the leftmost lane, and often times it's virtually impossible to go even the speed limit without staying there. It's still suggested that slow traffic keep right, but you're not going to get a ticket for cruising in the "passing lane".

On an odd tangent, I once took a cross-country road trip, and on those long stretches of I70 that run through the west, the majority of the sparse traffic you'll see say fuck all speed limits -- to the point that I saw an oversized-load truck carrying a giant windmill blade itself the size of an ordinary semi, and its envoy of numerous F150s or the like, fly past me (into the opposite lane even, oversized load and all) at at least 90mph, in the rain no less. Anyway, in the middle of Utah I'm flying down a long straight stretch of road at about that speed myself, and merge left to overtake an ordinary semi doing only 80ish in this 55mph zone, when I spot waaaaay off in the distance a glint of light off a car parked sideways on the median, which I (correctly) figured to be a cop. So I coasted back down to the speed limit by the time we got to him, making my overtake of the semi a long drawn-out process and causing the semi to decide to overtake me in turn, and as we pass the cop, me going the speed limit and the truck going about 15mph over, the cop pulls out... and pulls me over.

I'm thinking he must have somehow already clocked me from way off in the distance, but nope. He wanted to let me know that here in Utah the left lane is for passing only, and if I'm going to overtake another vehicle I should commit and accelerate and get quickly back in the right lane. That's right: passing at 70-80mph in a 55mph zone wasn't fast enough, I should have sped up and gotten back out of the passing lane faster.
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Re: 1125: "Objects In Mirror"

Postby jgoemat » Thu Nov 01, 2012 2:58 am UTC

If a semi had a mirror stuck to its grill and was travelling at the same speed you were, but in the opposite direction, would that correct the red shift?

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Re: 1125: "Objects In Mirror"

Postby ijuin » Thu Nov 01, 2012 6:30 am UTC

jgoemat wrote:If a semi had a mirror stuck to its grill and was travelling at the same speed you were, but in the opposite direction, would that correct the red shift?

Is it approaching or receding from you as time progresses?

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Re: 1125: "Objects In Mirror"

Postby garrettgu10 » Wed Aug 05, 2015 1:59 am UTC

Wait. Mirrors actually have a slight tortoise tint to them, which is easily seen by facing two mirrors at each other. That tint would potentially overshadow any slight immeasurable color shift due to the waves being stretched out from the car moving. Therefore, the color shift mentioned in the comic is trivial compared to the green-shift caused by the mirror. :idea:


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