explain xkcd - User contributions [en]

1619: Watson Medical Algorithm

2015-12-25T06:08:22Z

188.114.106.101: /* Explanation */ "perform autopsy" is not the only end node, so I deleted the sentence

{{comic
| number = 1619
| date = December 21, 2015
| title = Watson Medical Algorithm
| image = watson_medical_algorithm.png
| titletext = Due to a minor glitch, 'discharge patient' does not cause the algorithm to exit, but instead leads back to 'hunt down and capture patient'.
}}

==Republished comic==

This comic was updated and republished on the 22nd Dec -- [http://www.explainxkcd.com/wiki/images/archive/1/15/20151222113107%21watson_medical_algorithm.png click here to see the original version]

The explanation matched the updated version.

==Explanation==
{{incomplete|much more on the different procedures etc.}}
IBM's {{w|Watson (computer)|Watson}} is a natural language system designed to answer questions posed by humans. Recently, IBM has extended Watson to act as a {{w|clinical decision support system}}, using image analytics to aid physicians in medical decision making. In this comic, Randall shows a {{w|flowchart}} representing a possible algorithm for Watson, including bizarre techniques including surgical alteration of a patient to match a height and weight chart and squeezing the patient to remove yellow fluids. Like [[416: Zealous Autoconfig]], this comic pokes fun at a rigid, poorly-designed setup that ends up potentially doing more harm than good.

Modern medicine involves both standard processes and clinical judgement based around years of advanced training. An algorithm like this would have to be incredibly complicated in order to simulate the clinical judgement of a good doctor.

The algorithm depicted treats a patient as more of a machine or mechanical system than a living being, especially through decisions such as:

*Injecting oxygen into patients with low oxygen saturation, rather than treating the root cause.
*Removing and inspecting a skeleton, then diagnosing the patient's condition with a bone count.
*Dissecting a doctor "for parts" after consulting him or her for advice.
*Removing extra limbs from a patient if the count is 100 or more (This might be a reference to different number systems used in computers, as 100 is read in binary as four.)
*Determining whether the "build environment" of the patient is sane. This is most probably a reference to the configure script used in the {{w|GNU_build_system|GNU build system}}, which emits "checking whether build environment is sane" as one of its status messages.
*Rinsing the whole patient with a saline solution.
*Removing organs from a patient regardless of response to an organ donation request.

Other decisions appear to be entirely unrelated to the conditions upon which they are predicated:

*If the patient doesn't rate their pain on a scale from 0-10, sequence their genome, apply a {{w|tourniquet}}, and perform an {{w|autopsy}}
*If the patient's phone's battery is low, defibrillate until the battery is charged, sync photos, then administer general anesthesia
*If the patient is successfully comforted after an oxygen injection, check their medical history and apply skin grafts
*If green fluid is released from the patient, begin to cauterize
*If the patient has less than 100 limbs, check their Vitamin D level

The title text implies that, if the patient is so lucky to ever reach one of the two places with the option "discharge patient," a minor glitch will cause to program to go back to the ''hunt down and capture patient'' option which thus force the patient and the program to repeat the process again in an infinite cycle, that will only end once the patient give another rating of their pain level than on the 0-10 scale. Then the program will start to sequence their genome then apply a tourniquet and finally perform an autopsy, on what will in the end for certain be a deceased patient, but maybe not when the autopsy began. This will finally cause the patient to leave the cycle as a corpse.

This is one of many comics with [[:Category:Flowcharts|flowcharts]], amongst other a recent comic with that very name: [[1488: Flowcharts]].

This is the second comic in a row about health issues with the last comic being [[1618: Cold Medicine]].

The computer's behavior in this comic can be compared to the healthcare robot named Baymax in the movie {{w|Big Hero 6 (film)}}.

The comic was updated after it was first posted: the decisions for number of limbs were swapped.

==Transcript and Discussion of Medical Appropriateness==
{{incomplete|The transcript exists to make the comic accessible to the blind and people who can't see the comic. This transcript is not faithful to the comic as it contains a lot of text that is not in the comic, and is most certainly not screen reader friendly.}}
{| border=1
| | Step
| | Medically valid?
| | Conditions and following step
|-
| |
Draw Blood
| |
Phlebotomy is a normal early step in the diagnostic process, but not as first and unconditional step
| |
Record patient’s name
|-
| |
Record patient’s name
| |
OK
| |
Measure Patient’s height and Weight
|-
| |
Measure Patient’s height and Weight
| |
OK
| |
Consult Standard height/weight chart
|-
| |
Consult Standard height/weight chart
| |
OK
| |
Surgically adjust patient to match
|-
| |
Surgically adjust patient to match
| |
May be considered ethically dubious unless there are [http://www.gosh.nhs.uk/medical-information/procedures-and-treatments/limb-length-difference-and-limb-lengthening sound medical reasons] for doing so. Could be an allusion to {{w|Procrustes}}.
| |
Is patient coughing up blood?
|-
| width="33%" rowspan=2 |
Is patient coughing up blood?
| width="33%" rowspan=2 |
OK, coughing up blood is generally a sign that there is something wrong. Typical causes are respiratory tract infections (e.g. tuberculosis), lung trauma or pulmonary embolism.
| |
Yes: Gather blood and return it to body
|-
| |
No: Is patient still here?
|-
| width="33%" rowspan=2 |
Is patient still here?
| width="33%" rowspan=2 |
Not usually considered a step, but missing patients are a problem in some fields, psychiatry or intensive care for example.
| |
Yes: Record pulse rate
|-
| |
No: Hunt down and capture patient
|-
| |
Hunt down and capture patient
| |
Valid if patient should not have left the bed/unit, but the wording is possibly dubious.
| |
Is patient still here?
|-
| |
Gather blood and return it to body
| |
Dangerous idea in this case due to likelihood of contamination, although if safely done autotransfusion is an accepted medical technique to ensure a matching blood supply prior to a major operation, or to enhance stamina (blood doping)
| |
Record pulse rate
|-
| |
Record pulse rate
| |
OK, but maybe a little late.
| |
Is patient screaming?
|-
| width="33%" rowspan=2 |
Is patient screaming?
| width="33%" rowspan=2 |
Very important question, indicating patient is conscious, in pain, and aware pain is bad. First attenders can use it in classifying priorities (quiet patients may be more severely injured). Generally useful in assessing nerve damage, pain relief, etc.
| |
Yes: Ignore
|-
| |
No: Check blood O2 saturation
|-
| width="33%" rowspan=2 ` |
Check blood O2 saturation
| width="33%" rowspan=2 |
Only really indicated if the patient is in danger of hypoxia. Generally normal people should have a SpO2 of 98-100%, but in chronic lung disease this can fall as low to 80%, and in premature babies a SpO2 of 90% is usually targeted to avoid problems with retinopathy. If the SpO2 were to fall as low as 50%, the patient would definitely be dead or unconscious.
| |
>50%: Remove and inspect skeleton
|-
| |
<50%: Inject oxygen
|-
| width="33%" rowspan=2 |
Remove and inspect skeleton
| width="33%" rowspan=2 |
Fatal if patient is still alive when beginning. Also not a valid medical procedure in any way as it is impossible to remove most of the long bones of the body without destroying all surrounding tissue.
| |
Too many bones: Is fluid coming out of patient?
|-
| |
Too few bones: Request consult with human doctor
|-
| |
Request consult with human doctor
| |
Medically valid in the context of obtaining an opinion from a doctor in a different speciality who is better suited to treating the patient.
| |
Dissect doctor for parts
|-
| |
Dissect doctor for parts
| | This may be considered ethically dubious. Possible reference to the Doctor Who episode “{{w|The Girl in the Fireplace}}”
| |
Discharge patient
|-
| |
Discharge patient
| |
Acceptable, but patient would generally be dead by then.
| |
END STATE (before you read the title text)
|-
| width="33%" rowspan=2 |
Is fluid coming out of patient
| width="33%" rowspan=2 |
Unintended fluid release is always a problem. How significant a problem depends on where the fluid came from and if it is supposed to be coming from there. Red generally is due to blood, yellow is due to pus/tissue fluid/lymph and green signifies bacterial infection or bile salts (biliverdin). Could also relate to normal fluids being lost (e.g. urine, saliva, sweat)
| |
No: Squeeze patient
|-
| |
Yes: What color?
|-
| |
Squeeze patient
| |
Could be in the medical context is in providing external ventilation (see iron lung) or other means of removing fluid (e.g. squeezing pus from a boil).
| |
Is fluid coming out of patient
|-
| width="33%" rowspan=4 |
What color?
| width="33%" rowspan=4 |
Never underestimate the number of different types of fluid the body can produce.
| |
Yellow: Squeeze Patient
|-
| |
Black: Activate Sprinklers
|-
| |
Red: Ask patient to rate pain level
|-
| |
Green: Cauterize
|-
| |
Activate sprinklers
| |
Not medically valid. Presumably a reference to how much cleaning up will be required by this stage.
| |
Subdue patient
|-
| |
Subdue patient
| |
Potentially very important if patient is behaving dangerously to themselves and others around them (due to mental health issues e.g. psychosis or drugs) and/or is moving too much to be given treatment.
| |
Apply cream
|-
| |
Apply cream
| |
Medically valid as a form of barrier dressing to improve wound healing.
| |
Ask patient to rate pain level
|-
| width="33%" rowspan=4 |
Ask patient to rate pain level
| width="33%" rowspan=4 |
Useful in the sense that it provides the doctor with the means to ensure that the patient is receiving adequate analgesia during conditions of chronic and acute pain.
| |
0-8: Massage scalp
|-
| |
9: Admit for observation
|-
| |
10: Laser eye removal
|-
| |
Other response: Sequence genome
|-
| |
Massage scalp
| |
This would belong more to the domain of palliative care and reflexology rather than being an accepted medical treatment.
| |
Patient is healthy
|-
| |
Patient is healthy
| |
A subjective assessment of the health patient is often helpful in ruling out certain diagnoses. For example, one is less likely to suspect cancer in a fit, healthy 30 year old than a thin, lethargic 50 year old.
| |
Admit for observation
|-
| |
Admit for observation
| |
Useful in the context of 'watchful waiting', in which the doctor may be unsure if the patient actually has a condition that they suspect that the patient has. By keeping the patient on the ward for a few days, the clinician can monitor the progression of symptoms and rapidly initiate adequate treatment if medically warranted.
| |
Ask patient to rate pain level
|-
| |
Laser eye removal
| |
This is not a standard medical procedure. This could be a pun on laser eye surgery where a laser is used to correct visual problems (e.g. short-sightedness), or laser hair and tattoo removal.
| |
Admit for observation
|-
| |
Sequence genome
| |
Useful in the association of extremely rare point mutations with an organic illness. See for instance the Genome 10K Project or the Cancer Genome Atlas. Or in diagnosing extremely rare mutations that are not picked up by most commercial DNA screening tests (e.g. kidney failure due to INF2 mutation).
| |
Apply tourniquet
|-
| |
Apply tourniquet
| |
Useful to stop acute bleeding from an injured extremity, but if it is drawn too tightly it can cause neuromuscular damage.
| |
Perform autopsy
|-
| |
Perform autopsy
| | The patient has died, and Watson is being ordered to determine the cause of death. Note that the only way to reach this state is from "apply tourniquet", implying the cause of death is strangulation via tourniquet.
| | END STATE (taking the title text into account, the only possible one)
|-
| |
Inject oxygen
| |
May be fatal as injecting gases directly to the blood vessels can cause a serious embolism if it blocks blood flow to the brain or coronary arteries. However, if the oxygen is injected slowly into the venous circulation, it may be survivable as the bubbles may simply collect in the lungs where the oxygen is then slowly reabsorbed into the blood.
| |
Comfort patient
|-
| width="33%" rowspan=2 |
Comfort patient
| width="33%" rowspan=2 |
Psychological support to the patient and relatives is often useful after breaking news of a poor prognosis. It may also be useful in subduing the agitated or psychotic patient.
| |
Comforting successful: Review medical history
|-
| |
Comforting unsuccessful: Subdue patient
|-
| |
Review medical history
| |
Important early step, rather too late and conditional.
| |
Skin grafts
|-
| |
Skin grafts
| |
Only indicated if massive areas of the skin are damaged (typically due to burns)
| |
Count number of limbs
|-
| width="33%" rowspan=2 |
Count number of limbs
| width="33%" rowspan=2 |
Not really relevant in medicine, but may be of use to know the reason behind any missing or extra limbs on seeing the patient though a through review of the medical history will render this point moot. Probably a little late to be noticing this now.
| |
Fewer than 100: Measure Vitamin D
|-
| |
100+: Remove extra limbs
|-
| |
Remove extra limbs
| |
Medically indicated in cases of polymelia either due to cosmetic purposes or because the extra limbs pose a direct threat to the health of the baby.
| |
Subdue patient
|-
| width="33%" rowspan=2 |
Measure vitamin D
| width="33%" rowspan=2 |
Valid in diagnosis of bone related issues, for example if multiple or comminuted fractures were being counted as additional limbs/bones.
| |
Good: Check whether build environment is sane
|-
| |
Bad: Blood loss?
|-
| |
Check whether build environment is sane
| |
Could be technical reference to the installation of the algorithm in the robot, or could relate to the sanity of:
*The robot doctor
*The patient undergoing this procedure (before or after reaching this part of the process)
*The person who programmed the robot to perform this flowchart
*The person who allowed this state of affairs to occur (I'm looking at you [[Black Hat]])

This could also be a reference to the title text for [[371: Compiler Complaint]].

NB: Whether the build environment is sane is irrelevant to the flowchart.
| |
Rinse patient with saline solution
|-
| |
Rinse patient with saline solution
| |
Tepid sponging may be indicated if the patient has a high fever. Could also refer to internally rinsing patient with saline solution i.e. providing intravenous sodium chloride to boost circulating volume or to perform peritoneal dialysis.
| |
Is patient phone battery low?
|-
| width="33%" rowspan=2 |
Is patient phone battery low?
| width="33%" rowspan=2 |
Invalid in medical terminology, could be a technological metaphor for the patient's consciousness or stamina. "Your life-force is running out"
| |
Yes: Defibrillate
|-
| |
No: Sync photos from camera
|-
| |
Defibrillate
| |
Indicated in cases where there is ventricular fibrillation, and to a lesser extent in atrial fibrillation (chemical cardioversion with adenosine is usually preferred)
| |
Is patient phone battery low?
|-
| |
Sync photos from camera
| |
Definitely invalid. Could refer to the robot attempting to backup photos from a camera before attempting to repair it/attempting to back-up patient's consciousness.
| |
Administer general anesthesia
|-
| |
Administer general anesthesia
| |
Valid, but not at this stage. Only used when the procedure will invoke unnecessary distress or pain to the patient if they were to be awake beforehand.
| |
Discharge patient
|-
| width="33%" rowspan=2 |
Blood loss?
| width="33%" rowspan=2 |
Useful. Patient may die if this clinical sign is missed.
| |
Minor: Patient address changed?
|-
| |
Substantial: Apply cream
|-
| width="33%" rowspan=2 |
Patient address changed?
| width="33%" rowspan=2 |
Useful to ensure that the organisation has current contact details for the patient in the event that they may need to contact the patient (e.g. to arrange further appointments)
| |
Yes: Request organ donation
|-
| |
No: Patient is healthy
|-
| |
Request organ donation
| |
Generally done prior to registering an individual for a driving licence or to a medical practice, or to the relatives of the deceased if consent had not been acquired beforehand.
|Remove organs
|-
| |
Remove organs
| |
The only organs which can be safely removed from a living person without resulting in serious, chronic medical issues are the kidneys/lungs (only one can be removed), spleen, part of the liver (as long as one lobe is left it can regrow to its original size) and colon (usually consisting of the appendix only). With some serious lifestyle modifications, the pancreas, pituitary gland, frontal lobe of brain, half of the brain, adrenal glands, bladder and most of the gut can be removed. The heart can be removed from the body and replaced with an artificial pump for a few months at the most. However, such organ removals are only indicated if there is a genuine clinical need to do so due to the non-negligible risk of death associated with these operations.
| Discharge patient
|-
| |
Discharge patient
| |
Appropriate, if the patient is no longer suffering from any conditions requiring in-hospital care
| |
END STATE (before you read the title text)
|}

{{comic discussion}}
[[Category:Artificial Intelligence]]
[[Category:Flowcharts]]
[[Category:Computers]]

Talk:1145: Sky Color

2015-08-15T14:51:39Z

188.114.106.101:

I think most explanations of the the mirror issue overlook an even simpler explanation -- Things appear to be flipped such that left and right are reversed. However, that is only because you are used to things, such as people, rotating about a vertical axis, with top and bottom staying in the same position. If a clone of you stood on its head and you faced each other, your right arms would be on the same side (e.g. "closer to the door"). Now, if you look in a mirror, it is the same as seeing the clone flipped top to bottom. [[Special:Contributions/24.41.66.114|24.41.66.114]] 01:06, 6 September 2013 (UTC)

I have read that when you are in front of the mirror, the reason that it seems to reverse the horizontal or x-axis (left-right) view but not the vertical or y-axis view, is that the mirror actually reverses the z-axis front-back. The part nearest to the mirror reverses. Example, if you hold your right gloved hand in front of the mirror with the 5 fingers pointing to the mirror, the image that you see in front of the mirror is not similar to the left-hand glove, but it is the right glove turned inside-out. To test, wear a right latex glove, write something on it, then remove the glove, making the right glove inside out. If you can read what you had just wrote, it had reversed horizontally, but not vertically, assuming same frames of reference.

Of course with '''''vertical''''' mirror vertical axis is selected: perceived switching of left and right (really close with far to mirror surface). When '''standing on''' '''''horizontal''''' mirror we will perceive switching bottom from top. --[[User:JakubNarebski|JakubNarebski]] ([[User talk:JakubNarebski|talk]]) 09:09, 10 December 2012 (UTC)

You're certainly correct, but I think that the original question is not really asking about text (or other things) which are perpendicular to the mirror, but rather text which is parallel to it (and thus the close vs. far doesn't come into it). For example, when reading signs in your rear view mirror or holding a book in front of your chest while looking in a mirror. I've added a little bit to the explanation to attempt to help clarify what's happening in that situation. I'm not sure if it really helps or not. [[User:KeithyIrwin|KeithyIrwin]] ([[User talk:KeithyIrwin|talk]]) 10:00, 10 December 2012 (UTC)

Easier way to describe it: Imagine you hold a piece of glass. Write on the glass and hold it in front of the mirror, so that you can see both the original text and the mirrored text. Both versions of the text will look identical. So the mirror doesn't change anything. [[Special:Contributions/62.220.2.194|62.220.2.194]] 11:10, 10 December 2012 (UTC)

Another way: draw a line between the real object and its reflection. Things are reflected around that line. If that line is going up & down (relative to your eyes), then things are reflected left/right (relative to your eyes). If that line is horizontal (again relative to your eyes), then things are reflected top/bottom. So it's not so much whether the mirror is horizontal or vertical, but rather what direction you are looking into the mirror (although that can be influenced a lot by the mirror's orientation).[[User:CityZen|CityZen]] ([[User talk:CityZen|talk]]) 04:17, 11 December 2012 (UTC)

I always wonder: Since the sky goes from red to blue to red and the optical spectrum goes from red to green to blue. How come the sky is never green?
: Because of human color perception. You only perceive green in polychromatic light when said light is stronger in the middle wavelengths than the low or high wavelengths; in other words, you would need a process in the sky that removed ''both'' the high and low wavelengths from white light. As the sun sets, only the lower wavelengths are removed, so you perceive yellows and reds -- this perception of color is "one-sided", i.e. it is not interfered with by even longer wavelengths. By the way, sometimes you do see green briefly in the sky, it's called a [http://en.wikipedia.org/wiki/Green_flash Green Flash]. --[[User:Prooffreader|Prooffreader]] ([[User talk:Prooffreader|talk]]) 16:41, 10 December 2012 (UTC)
::I used to go outside after a rain storm during the day, and sometimes the sky would seem very green. The effect could last for hours. [[Special:Contributions/76.122.5.96|76.122.5.96]] 12:15, 12 December 2012 (UTC)
: The sky ''is'' green, at times. Growing up in the Upper Midwest (USA), I quickly learned that green sky means it's time to watch out for tornadoes. I don't know the actual connection between the two situations--I would guess from the previous comment that whatever atmospheric conditions create tornado conditions also "edit out" both high and low wavelengths, at least to a degree. [[Special:Contributions/129.176.151.14|129.176.151.14]] 14:44, 12 December 2012 (UTC)

This sentence doesn't make sense: "(from "his" right to left instead of from "his" left to right)" [[User:Trek7553|Trek7553]] ([[User talk:Trek7553|talk]]) 15:15, 10 December 2012 (UTC)

Repeat Character Watch: The girl has appeared previously in [[842: Mark]], [[892: Null Hypothesis]], [[1058: Old-Timers]], and [[1104: Feathers]] (A similar looking character also appears in [[635: Locke and Demosthenes]] but this is actually the character Valentine from the book Ender's Game). The mother is seen in comics [[806: Tech Support]] and [[813: One-Liners]]. [[User:Lcarsos|lcarsos]]_a ([[User talk:Lcarsos|talk]]) 18:12, 10 December 2012 (UTC)

About [http://www.explainxkcd.com/wiki/index.php?title=1145:_Sky_Color&diff=22416&oldid=22414 this edition]: 1/(x^4) does not look like a root to me. IMHO the forth root of x would be more like x^(1/4) but it's not the formula from the comic. (I'm too lazy to try to type lambda). [[User:Lmpk|Lmpk]] ([[User talk:Lmpk|talk]]) 19:00, 10 December 2012 (UTC)

:You are correct. It's been fixed. The editor that made that edit was probably confusing 1/x4 with x1/4, the latter of which would indeed be the fourth root. [[User:Lcarsos|lcarsos]]_a ([[User talk:Lcarsos|talk]]) 19:53, 10 December 2012 (UTC)

[http://math.ucr.edu/home/baez/physics/General/BlueSky/blue_sky.html This page], linked from the explanation says that "the most strongly scattered indigo and violet wavelengths stimulate the red cones slightly as well as the blue, which is why these colours appear blue with an added red tinge." -- this seems rather strange. Assuming the cones are simulated based on frequency/wavelength, ultra-blue colors shouldn't stimulate the red cones because the electromagnetic spectrum is linear, not circular, despite the appearance of similarity between violet and red. Or am I missing something? --[[User:Waldir|Waldir]] ([[User talk:Waldir|talk]]) 16:14, 11 December 2012 (UTC)
: If you look at the response curve (middle of cited page) you'll see that red receptors have two peaks, one in the red wavelengths, and another (very tiny one) in the violet. That's why purple (which is red + blue) looks so similar to violet, and why the "color wheel" works. [[Special:Contributions/207.225.239.130|207.225.239.130]] 21:59, 11 December 2012 (UTC)
:: PS: "first years" is an idiom. Wouldn't that be "first year students" to be proper English? [[Special:Contributions/207.225.239.130|207.225.239.130]] 22:05, 11 December 2012 (UTC)
:::Idioms are "proper English" too. There is no doubt about what is meant here (or at least, I hope there isn't, but perhaps there are regional differences that mean some English speakers don't say "first years" to talk about students in their first year), and the register is not unduly colloquial for this kind of a site. 14:00, 12 December 2012 (UTC)
: The easiest way to explain mirrors is: they don't change left and right, they change forward and backward. What is farther from the mirror appears farther in the mirror. If you look at yourself, your nose and the nose of your reflection are the closest parts of the body together (at least in a bathroom mirror :-)), so *if there were* another person standing where the mirror *simulates* it, that person would wave it's right arm when you wave your left. But in a "absolute reference frame", both image and original wave their arm nearest to the door. Interestingly automobile drivers don't make this error: if you see a car in the rear mirror blinking left you don't assume they want to turn right...

There was a hilarious [http://en.wikipedia.org/wiki/Get_Fuzzy Get Fuzzy] strip where Rob tried to explain why the sky is blue to Satchel, but I can't find it. [http://homepage.smc.edu/morse_peter/phy14/LightOptics/GetFuzzyWhyIsTheSkyBlue.jpg This one?][[Special:Contributions/98.174.41.183|98.174.41.183]] 00:49, 31 December 2012 (UTC) Yes that's the one. --[[User:Smartin|Smartin]] ([[User talk:Smartin|talk]]) 04:23, 1 January 2013 (UTC)

: I would also just like to add that, as I understand it, the Sun puts out a lot more blue light than violet light, so it would make sense for blue to dominate. After green light, where the Sun's output peaks, the intensity of the light starts dropping dramatically. {{unsigned ip|71.104.183.59}}

I don't think that woman is Megan. She looks like a black-haired version of Ponytail. {{unsigned ip|108.162.219.203}}
:Have to agree. Doesn't look like Megan. [[Special:Contributions/108.162.210.177|108.162.210.177]] 23:53, 22 June 2015 (UTC)

The mirror explanation is convoluted. The question tricks you into thinking there's right/left symmetry being mixed up, when the symmetry is actually across the surface of the mirror. That's it. [[Special:Contributions/108.162.215.94|108.162.215.94]] 01:41, 28 September 2014 (UTC)

User talk:JakubNarebski

2015-08-15T14:49:51Z

188.114.106.101: Created page with "I have read that when you are in front of the mirror, the reason that it seems to reverse the horizontal or x-axis (left-right) view but not the vertical or y-axis view, is th..."

I have read that when you are in front of the mirror, the reason that it seems to reverse the horizontal or x-axis (left-right) view but not the vertical or y-axis view, is that the mirror actually reverses the z-axis front-back. The part nearest to the mirror reverses. Example, if you hold your right gloved hand in front of the mirror with the 5 fingers pointing to the mirror, the image that you see in front of the mirror is not similar to the left-hand glove, but it is the right glove turned inside-out. To test, wear a right latex glove, write something on it, then remove the glove, making the right glove inside out. If you can read what you had just wrote, it had reversed horizontally, but not vertically, assuming same frames of reference.