Page 265 - AllbertEstens

CAC MANG SPIN

Ly thuyet cua chung toi con noi gi ve khong-thdi gian? De

bat dau, ta hay xem xem cac trang thai liidng tit cua dien tich

va the tich nhin nhii the nao? Lieu khong gian co dtfdc tao bcfi

rat nhi£u nhiing khol lap phUdng hay nhiing khoi cau nho? Cau

tra ldi la: Khong — thUc te khong ddn gian nhu vay. Tuy nhien,

chung ta co the ve cac gian do bieu dien cac trang thai ltfdng tut

cua the tich va dien tich. Doi vdi nhiing ngUdi lam viec trong

linh vUc nay nhu chung toi thi nhiing gian do nay la rat dep vi

no co moi quan he v6i mot nganh rat tao nha cua toan hoc.

De th^fy nhiing gian do nay “van hanh” nhu th£ nao, ta

hay tUdng tUdng co mot khol khong gian co hinh dang tUa nhu

mot khoi lap phtfdng, nhu dUdc minh hoa cl Hinh 2. Trong cac

gian do, chung ta ve khoi l^p phUdng nay nhii mot cham (bieu

diln the tich) vdi sau dvidng chia ra (bieu dien 6 mat cua khol

lap phUdng). Chung ta cung can phai viet mot con so" canh dau

cham de chi ro the tich va canh moi dUcfng ghi mot con so" de chi

dien tich cua mat ma diidng do bieu diln.

Tiep theo, gia sit rang chung ta dat mot hinh chop len

tren khol lap phUdng. Hai khoi da dien co mot mat chung nay

dUdc ve nhu hai cham (hai the tich) nol vdi nhau bang mot

dUdng (bieu diin mot mat chung). Khol lap phiidng con co 5 mat

khac (dUdc bieu dien bang 5 dUdng chia ra) va khol chop co 4

(ling vdi 4 dUdng chia ra). Tii day de dang ve diidc gian do (gom

cac dau cham va cac dUdng) ijtng vdi nhiing s^p xep phiic tap

hdn cua tat ca cac khol da dien khac. Cu the la moi da dien the

tich trd thanh mot cham (hay con goi la nut) va moi mot mat

phing cua da dien trd thanh mot dUdng, con diidng nol hai nut

utng vdi mat chung cua hai da dien. Cac nha toan hoc goi gian

do cac dUdng nay la do thi.

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