# light... is absorbed and reflected ... only the higher energy wavelengths can do this **URL:** \ **Category:** Cecil's Columns/Staff Reports\ **Created:** [September 7, 2017, 3:31am UTC](https://boards.straightdope.com/t/light-is-absorbed-and-reflected-only-the-higher-energy-wavelengths-can-do-this/795707 "2017-09-07T03:31:52Z")\ **Posts on this page:** 5\ **Page:** 1
**Author:** ![Melbourne](https://avatars.discourse-cdn.com/v4/letter/m/b5e925/32.png) [@Melbourne](https://boards.straightdope.com/u/Melbourne)\ **Post date:** [September 7, 2017, 3:31am UTC](https://boards.straightdope.com/t/light-is-absorbed-and-reflected-only-the-higher-energy-wavelengths-can-do-this/795707/1 "2017-09-07T03:31:52Z")
Bzzzzt. Only the shorter wavelengths can … what ? Be reflected? Be absorbed? Be absorbed and reflected and seen? Red blood looks blue when seen through milk. Ok. And what color is the rest of you? Why does it look different when viewed through milk? I don’t doubt the technically accuracy of this answer. But the content is obscure, as though viewed through milk. ---
**Author:** ![watchwolf49](https://avatars.discourse-cdn.com/v4/letter/w/e9c0ed/32.png) [@watchwolf49](https://boards.straightdope.com/u/watchwolf49)\ **Post date:** [September 7, 2017, 6:41am UTC](https://boards.straightdope.com/t/light-is-absorbed-and-reflected-only-the-higher-energy-wavelengths-can-do-this/795707/2 "2017-09-07T06:41:16Z")
I think what **The Master** is saying is that skin is somewhat translucent … light rays penetrate down through the layers of cells a certain distance … blue light is more energetic than red light, so the blue light penetrates deeper into the skin … down at these deeper layers are the blood vessels and only the blue light gets that far, and still be able to reflect back out … all the red light will have been absorbed by then … No, I don’t understand the literary allusion to Fruit Loops either, nor why milk is supposed to turn them different colors … Article in question: [“If blood is red why do your veins look blue?”](http://www.straightdope.com/columns/read/1419/if-blood-is-red-why-do-your-veins-look-blue) ---
**Author:** ![Exapno\_Mapcase](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/exapno_mapcase/32/1051_2.png) [@Exapno\_Mapcase](https://boards.straightdope.com/u/Exapno_Mapcase)\ **Post date:** [September 7, 2017, 6:10pm UTC](https://boards.straightdope.com/t/light-is-absorbed-and-reflected-only-the-higher-energy-wavelengths-can-do-this/795707/3 "2017-09-07T18:10:12Z")
> [@watchwolf49](#): > > I think what **The Master** is saying … Oops. > [@](#): > > **A Staff Report from the Straight Dope Science Advisory Board** > If blood is red why do your veins look blue? > August 12, 1999 > > Dear Straight Dope: > > What color is blood inside the body? If it is red then why do veins look blue? > > — WishNmoon > > **SDStaff Hawk** replies: ---
**Author:** ![minor\_details](https://avatars.discourse-cdn.com/v4/letter/m/74df32/32.png) [@minor\_details](https://boards.straightdope.com/u/minor_details)\ **Post date:** [September 15, 2017, 5:19pm UTC](https://boards.straightdope.com/t/light-is-absorbed-and-reflected-only-the-higher-energy-wavelengths-can-do-this/795707/4 "2017-09-15T17:19:38Z")
> [@watchwolf49](#): > > I think what **The Master** is saying is that skin is somewhat translucent … light rays penetrate down through the layers of cells a certain distance … blue light is more energetic than red light, so the blue light penetrates deeper into the skin … down at these deeper layers are the blood vessels and only the blue light gets that far, and still be able to reflect back out … all the red light will have been absorbed by then … Not quite. The skin absorbs blue and green light much more strongly than red light, so it doesn’t penetrate nearly as deep. The color you see for the veins is due to scattered light, and this scattered light is much more likely to be red than blue (as the blue light is absorbed). As this paper [https://www.spiedigitallibrary.org/journals/Journal-of-Biomedical-Optics/volume-17/issue-9/090901/Optical-properties-of-human-skin/10.1117/1.JBO.17.9.090901.full?SSO=1](https://www.spiedigitallibrary.org/journals/Journal-of-Biomedical-Optics/volume-17/issue-9/090901/Optical-properties-of-human-skin/10.1117/1.JBO.17.9.090901.full?SSO=1) says, “One implication of the wavelength dependence of scatter is that blue and green light that has returned to the surface of the skin will have, on average, travelled less deeply than red light. This is considered the primary reason why blood vessels and pigmented nevi that are situated deeper within the skin are only able to absorb light from the red end of the spectrum and therefore appear bluer than their superficial equivalents” ---
**Author:** ![Irishman](https://avatars.discourse-cdn.com/v4/letter/i/b487fb/32.png) [@Irishman](https://boards.straightdope.com/u/Irishman)\ **Post date:** [September 17, 2017, 6:00pm UTC](https://boards.straightdope.com/t/light-is-absorbed-and-reflected-only-the-higher-energy-wavelengths-can-do-this/795707/5 "2017-09-17T18:00:08Z")
> [@Melbourne](#): > > Bzzzzt. > > Only the shorter wavelengths can … what ? Be reflected? Be absorbed? Be absorbed and reflected and seen? Shorter wavelengths equal higher frequencies and higher energy. UV has shorter wavelengths than blue light, and X-rays even shorter wavelengths. The blues are scattered (i.e. reflected) while the reds are absorbed. > [@](#): > > Red blood looks blue when seen through milk. Ok. And what color is the rest of you? Why does it look different when viewed through milk? The column explains, “milk [has] a similar ratio of fat, proteins, and water in emulsion as skin”. Thus, the optical properties are considered to be similar to skin. It has the same amount of scatter in the same wavelengths. > [@watchwolf49](#): > > No, I don’t understand the literary allusion to Fruit Loops either, nor why milk is supposed to turn them different colors … Fruit Loops?