phai rat hay khong?
The la Galilei can cu theo tinh ding thoi cua con lie lap ban ve, thiet ke ra dong ho qua lie, va viet mpt ban thuyet minh chi tiet. Ve sau, mpt nguoi Ha Lan dua theo ban thiet ke va ban thuyet minh d6 da che thanh cong
m o t chiec dong ho hoan chinh. Do la chiec dong ho qua
Idc dau tien cua the gioi, dugc goi la "dong ho Galilei".
T u t h i nghiem k i e m tra chiec vuong m i e n cua Archimedes, Galilei lai n g h i toi viec u n g d u n g ket qua t h i n g h i e m do trong nghien c u u t i n h chat lire hoc va vat ly cua hop k i m . Khong lau sau, Galilei thong qua xac d i n h
trong lucmg cua vat the a trong nuac, phat hien thay
trong l u g n g giam nhe k h i cho vat the vao bang trong l u o n g nuoc m a no choan ch6, ong phat m i n h ra loai can
ty trong, c6 the dg dang biet duoc ty trong cua cac loai
hop k i m . Ong da viet m o t l u a n van gioi thieu nguyen ly, p h u o n g phap s i i d u n g loai can do. Rat n h i e u nha toan hoc da ca ngoi l u a n vSn do cua Galilei. Nha toan hpc Ricci dem ban l u a n vSn do chuyen t o i dai cong tuoc cai q u a n vung Pisa, va n h a n luc ong ta to ra rat hai long da nhac t o i d o i song kho khSn cua Galilei. N h o the Galilei
duQC c u giir chiic giao su toan hoc truong Dai hoc Pisa.
N a m 1589, t r u o n g D a i hoc Pisa trao t h u phong Galilei - sinh vien chua he tot nghiep cua t r u o n g nay, chuc v u glao su. N a m do, Galilei m o i 25 tudi.
Vao n a m t h i i hai, sau k h i t r o lai t r u o n g Dai hoc Pisa,
Galilei phat bieu m p t l u a n van rat c6 sue nang: "Ban ve
trong luc", Ian dau tien n e u ra d i n h luat r o i t u do cua vat
the: "Vat the, bdtke to, nhd, nhe, nang the ndo, trong qua
trinh roi tu do, neu khong ke toi dnh huang sdn sinh do tra luc cua khong khi, thi toe do roi cua chung hoan toan
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nhu nhau". D i e u nay p h u d i n h nguyen ly cua Aristotle la: "Vat the cdng nang thi rod cdng nhanh". H a n h dong d a m
tuyen chien voi " t h a n h n h a n " nay gay xon xao Ion trong ca truong Dai hoc Pisa, b i b g n t i n do cua Aristotle x i i m vao cong kich:
- H o a n toan la lao leu!
- Aristotle l a m sao sai duoc? L a m sao c6 the n h u the! De hoan toan danh guc q u a n d i e m sai l a m cua Aristotle, tra dua phai p h a n d d i m i n h , Galilei quyet d i n h l a m m o t t h i nghiem de c h u n g m i n h quan d i e m cua m i n h . Ong chon dia d i e m t h i n g h i e m la thap nghieng Pisa n o i tieng.
Do la m o t ngay dep troi cua n a m 1590. M o i hoc gia, sinh vien, dan chung t h a n h Pisa l u l u o t t o i gan thap Pisa,
xem Galilei bieu dikn t h i nghiem. Bon t i n do cua Aristotle
ho t u o n g len: "Hpc thuyet cua Aristotle tien b o i tuyet d o i khong sai!"; "Ten tieu tot t h d i tha nhat d i n h la ke dien!"...
Vao khoang trua h o m do, Galilei d i vao cua thap, roi leo len cau thang xoan 6c, len toi d i n h thap cao 54 met.
M o i nguoi 6 chan thap cang mat ra m a n h i n len d i n h thap. Chi thay Galilei 6 tren d i n h thap, hai tay cam hai qua cau sat. Ong het to de m o i nguoi duoi chan nghe thay:
- Qua cau nay nang 10 kg, qua cau kia nang 1 kg. Bay gid toi Cling tha xuong hai qua cau t h i chung r o i dong thoi m o t luc xuong dat. M o i nguoi hay chii y n h i n that can than m a xem!
Noi xong, hai qua cau da roi khoi tay Galilei. "Ung!" Moi nguoi deu nhin thay ca hai qua cau dong thai roi xuong mat dat.
' - Galilei thing r6i! - Moi nguoi reo vang len nhu sam.
Chi CO bon phan doi Galilei thi ha mom ra, tiu nghiu,
khong dam ban tan ho he gi nua.
Thanh cong cua buoi thuc nghiem da danh do ket luan cua Aristotle ma may ngan nSm qua khong ai dam hoai nghi, chi luon mieng noi la "chan ly"(!)
Nhung thanh cong do lai dan den tai hoa cho Galilei! Nhung giao su Dai hoc Pisa vdn khong chiu tin a mdt ho, cang khong tin la Aristotle sai lam, noi bay la Galilei yem
ma thuat vao trong qua cau sit... Ho tim moi each cong
kich, tay chay Galilei. NSm 1892, Galilei tuc gian tir bo chuc vu giao su, Ian thu hai roi khoi truang Dai hpc Pisa.
Nam thang kho quen
Mat noi day hoc, Galilei tay tr^ng tra ve gia dinh. Nguoi cha dau 6m da lau ngay, nhin dua con ch4ng tim ra loi nao de sinh ke, rat lo iSng cho tuong lai ciia Galilei. May ngay sau, ong 6m nSng, qua doi.
Me mat som, ca gia dinh van trong a thu nhap cua
cha de s6ng qua ngay. Con nay thi Galilei 28 tuoi dua lu em trai, em gai lam vao canh s6ng ban han, dang thuong biet bao. Mot thoi gian dai, Galilei phai nhan lam cac cong viec lat vat de c6 tien nuoi cac em. Khong lau sau, nho mot nguoi ban giup do, Galilei lai dugc bo
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nhiem chuc giao su truong Dai hoc Padua, day toan va thien van hpc.
Truang Dai hoc Padua nam a nuoc Cong hoa Venice. Venice cung nhu Florence, deu la mot nuoc thanh vien ciia Italia. Net khac la Venice la mot thanh pho rat vui ve,
CO vu moi nguoi tu do kham pha, thu vien a day phong
phu sach bao han moi noi 6 chau Au, truang Dai hoc Padua thoat khoi su kiem toa cua toa thanh La Ma, ma rong cua don nhan nhung tu tuong, tin nguong khac nhau. Galilei a do khong con bi bai xich do da tim ra nhung sai lam cua Aristotle. Co the c6 nguoi khong dong tinh voi hoc thuyet cua ong, nhung khong c6 nguoi lam nhuc ong.
Hit tho khong khi tu do cua Venice va Padua, Galilei tua nhu bien thanh mot con nguoi moi, song giua ban be nhiet tinh mong ong "an cu lac nghiep" 6 truang dai hoc do.
That ly thu la gia day hinh hoc dau tien cua Galilei a Padua da c6 sue hap d&n sinh vien manh den the! Ho im lang lang nghe, va roi v6 tay hoan nghenh khi Galilei giang bai xong. Sau do, nha truang phai chon cac giang duong Ian nhat trong truang de Galilei giang toan hoc, moi dap ung yeu cau cua sinh vien toi nghe giang.
Trong may nam dau a Padua, Galilei vua giang day, vxra don sue vao nghien cuu lire hoc. Ong phat hien hien tuong rat quan trong trong vat ly: Quan tinh cua vat th^ 111
khi chuyen dong. Ong da tien hanh a do thi nghiem chuyen dong cua vat tren mat phing nghieng, rat noi tieng; tong ket ra mdi quan he so luong giua cu ly va thoi gian khi vat the roi tu do; con nghien cuu van dong cua
dan phao... Khai niem ve "gia toe" cung la do Galilei dua
ra Ian dau tien, rat chinh xac. Vao nSm 1593, ong phat minh chiec nhiet ke khong khi dau tien de do than nhiet cho nguoi benh khi hi phat sot...
Vao nam 1600, Galilei dang lam cong viec giang day dai hoc thi xay ra viec nha triet hoc noi tieng Italia la Bruno, do tuyen truyen thuyet cua Copernicus, sau 10 nSm hi day doa trong song sat, ngay 17 thang 2, da bi Giao hoang xii tu tren gian thieu, 6 quang truong La Ma. Galilei biet dugc tin tham khoc do, long dau nhu cat, bi thuong khon cung. Galilei tuy cung la mon do cua Copernicus nhimg khi do chua dam cong khai bien ho cho Bruno. Nhung sir kien do da lam cai bien phuong huong nghien cuu cua Galilei. Ong chuyen tir doi tuong nghien cuu la lire hoc va vat ly hoc sang nhung van de cua linh virc vu tru hoc. Ong da tien hanh rieng cac loai thi nghiem khoa hoc, nham c6 gang phat trien hon mot buoc nua hoc thuyet cua Copernicus.
Mua dong nam 1604, c6 mot ngoi sao moi sang la thuong xuat hien tren bau trol. Vi khach khong mdi ma den do da hap dan sir chii y cua nhieu nguol. Vi khach ay toi miia xuan nam sau lai mat di mot each than bi. Moi nguoi tranh luan soi noi, neu bao cau hoi: "Do la ngoi sao
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nao? No tu dau toi, va lai di dau? Nhiing ngoi sao diem day tren man dem xet cho ciing thi van dong theo quy luat the nao?". Nhung chang c6 ai giai dap duoc ro rang nhting cau hoi do.
Galilei dem dem luu y quan sat ngoi sao la ay. Gang ngay ong cang nhan ra loai nguoi con biet it qua ve nhung hi mat cua vu tru.
Nhung chi dua vao mat nguoi binh thuong de quan sat thi cung chi quan sat duoc 6 muc do ban che ma thoi,
luc do lai chua c6 kinh vikn vong. Galilei nghi hoai toi
viec lieu c6 the c6 each nao lam cho thi luc ciia con nguoi cang tinh, nhay, cang mo rong hon, gidng nhu con mat thien ly trong truyen than thoai c6 the nhin thay nhung vi sao 6 t h i m xa... hay khong?
Ong het tram tu suy nghl lai tinh tinh, toan toan, tim toi ve van de do. Galilei tCmg noi vol ban be: