{"id":464,"date":"2010-09-03T14:26:26","date_gmt":"2010-09-03T18:26:26","guid":{"rendered":"https:\/\/scottaaronson.blog\/?p=464"},"modified":"2010-09-03T14:26:26","modified_gmt":"2010-09-03T18:26:26","slug":"physics-for-doofuses-why-beds-exist","status":"publish","type":"post","link":"https:\/\/scottaaronson.blog\/?p=464","title":{"rendered":"Physics for Doofuses: Why Beds Exist"},"content":{"rendered":"

I promised to blog more about research, and I will.\u00a0 Unfortunately, in the one week between my world tour and the start of the fall semester, I’ve been spending less time on quantum complexity research than on sleeping on a new mattress that I bought.\u00a0 This has provided ample time to ponder the following question, which I’ve decided to add to the Shtetl-Optimized<\/em> Physics for Doofuses series<\/a>:<\/p>\n

Why is a soft bed more comfortable than a hard one?<\/em><\/p>\n

At first glance, this question seems too<\/em> doofusy even for a series such as this, which makes its target audience clear.\u00a0 The trouble is that, while perfectly reasonable-sounding answers immediately suggest themselves, several of those answers can be shown to be wrong.<\/p>\n

Let’s start with the most common answer: a soft bed is more comfortable than a hard bed because it molds to your shape. \u00a0 The inadequacy of this answer can be seen by the following thought experiment: lie on a soft bed, and let it mold to your body.\u00a0 Then imagine that the bed retains exactly the same molded shape, but<\/em> is replaced by ceramic.\u00a0 No longer so comfortable!<\/p>\n

Ah, you reply, but that’s because a ceramic bed doesn’t change <\/em>its shape as you shift positions throughout the night.\u00a0 But this reply is still inadequate—since even if you’re lying as still as possible, it still<\/em> seems clear that a soft bed is more comfortable than a hard one.<\/p>\n

So it seems any answer needs to start from the observation that, even when you’re lying still, you’re not really<\/em> lying still: you’re breathing in and out, there are tiny vibrations, etc.\u00a0 The real point of a soft bed is to create a gentler potential well, which absorbs the shocks that would otherwise be caused by those sorts of small movements.<\/p>\n

(I was tempted to say the point is to damp<\/em> the movements, but that can’t be right: trampolines are designed for minimal damping, yet sleeping on a trampoline could actually be pretty comfortable.\u00a0 So the essential thing a bed needs to do is simply to make way<\/em> in response to small movements and vibrations.\u00a0 How hard the bed tries to spring back to its original shape is a secondary question—the answer to which presumably influences, for example, whether you prefer an innerspring or a memory-foam mattress.)<\/p>\n

So then why aren’t beds even softer than they are?\u00a0 Well, the limit of infinite<\/em> softness would be a bed that immediately collapsed to nothing when you lay on it, dropping you to the floor.\u00a0 But even before that limit, a bed that was too soft would give you too much freedom to shift into awkward positions and thereby cause yourself back problems.\u00a0 This suggests an answer to a question raised by a colleague: is the purpose of a bed to approximate, as well as possible on the earth’s surface, the experience of sleeping in zero gravity?<\/em>\u00a0 Unless I’m mistaken, the answer is no.\u00a0 Sleeping in space would be like sleeping on a bed that was too soft, with the same potential for back problems and so forth.<\/p>\n

Given that lying in bed is normally the least active thing we do, I find it ironic that the only reasons we lie in bed in the first place (as opposed to, say, on steel beams) are dynamical<\/em>: they involve the way the bed responds to continual vibrations and movements.<\/p>\n

I’ll be grateful if knowledgeable physicists, physiologists, or sleepers can correct any errors in the above account.\u00a0 Meantime, the next time your spouse, partner, roommate, parent, etc. accuses you of lounging in bed all afternoon like a comatose dog, you can reply that nothing could be further from the truth: rather, inspired by a post on Shtetl-Optimized<\/em>, you’re struggling to reconcile your modern understanding of the physics and biology of lying in bed with the prescientific, phenomenal experience<\/em> of lying in bed, and thereby make yourself into a more enlightened human being.<\/p>\n


\n<\/p>\n","protected":false},"excerpt":{"rendered":"

I promised to blog more about research, and I will.\u00a0 Unfortunately, in the one week between my world tour and the start of the fall semester, I’ve been spending less time on quantum complexity research than on sleeping on a new mattress that I bought.\u00a0 This has provided ample time to ponder the following question, […]<\/p>\n","protected":false},"author":2,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"advanced_seo_description":"","jetpack_seo_html_title":"","jetpack_seo_noindex":false,"_jetpack_memberships_contains_paid_content":false,"footnotes":"","jetpack_publicize_message":"","jetpack_publicize_feature_enabled":true,"jetpack_social_post_already_shared":false,"jetpack_social_options":{"image_generator_settings":{"template":"highway","default_image_id":0,"font":"","enabled":false},"version":2},"_wpas_customize_per_network":false},"categories":[18,19],"tags":[],"class_list":["post-464","post","type-post","status-publish","format-standard","hentry","category-embarrassing-myself","category-physics-for-doofuses"],"jetpack_publicize_connections":[],"jetpack_featured_media_url":"","jetpack_sharing_enabled":true,"_links":{"self":[{"href":"https:\/\/scottaaronson.blog\/index.php?rest_route=\/wp\/v2\/posts\/464","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/scottaaronson.blog\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/scottaaronson.blog\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/scottaaronson.blog\/index.php?rest_route=\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/scottaaronson.blog\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=464"}],"version-history":[{"count":0,"href":"https:\/\/scottaaronson.blog\/index.php?rest_route=\/wp\/v2\/posts\/464\/revisions"}],"wp:attachment":[{"href":"https:\/\/scottaaronson.blog\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=464"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/scottaaronson.blog\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=464"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/scottaaronson.blog\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=464"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}