到1917年，斯萊弗量測了25個「螺旋星雲」的徑向速度，發現除了三個星系之外，其它星系都以相當快的速度遠離我們。斯萊弗自己推測，這可能是由於我們自己星系的運動，就像在他的樣本中一樣，那些向我們移動的星系和那些遠離我們的星系大致相反的方向[20]。事後看來，這是第一個支援膨脹宇宙模型的數據。後來，埃德溫·哈伯將斯萊弗和其它徑向速度的光譜測量與哈伯自己對星系距離的測定相結合，導致哈伯發現了星系距離和紅移之間的比例關係（當時是粗略的），今天稱為哈伯-勒梅特定律（以前稱為哈伯定律，國際天文學聯合會2018年10月的決定建議使用這個新名稱[21]），是由哈伯和休馬森於1929年提出，並成為膨脹宇宙（英語：Expansion of the universe）現代模型的基礎。
Nesto (sic) Slipher, 93, Astronomer, Dies, The New York Times (Flagstaff, AZ), November 9, 1969: 47 (November 10, 1969), ISSN 1452424請檢查|issn=值 (幫助)請檢查|publication-date=中的日期值 (幫助); 使用|accessdate=需要含有|url= (幫助)
Way, M.J.; D. Hunter (編). Origins of the Expanding Universe: 1912–1932.. San Francisco: ASP Conference Series 471. Astronomical Society of the Pacific. 2013.
Nussbaumer, Harry. 'Slipher's redshifts as support for de Sitter's model and the discovery of the dynamic universe' In Origins of the Expanding Universe: 1912–1932. Astronomical Society of the Pacific. 2013: 25–38.Physics ArXiv preprint （頁面存檔備份，存於網際網路檔案館）
O'Raifeartaigh, Cormac. The Contribution of V.M. Slipher to the discovery of the expanding universe in 'Origins of the Expanding Universe'. Astronomical Society of the Pacific. 2013: 49–62.Physics ArXiv preprint （頁面存檔備份，存於網際網路檔案館）
Graves Hoyt, William. Crawford Jr., Bryce; McEuen, Caroline K. , 編. Vesto Melvin Slipher. Biographical Memoirs of the National Academy of Sciences of the United States of America (National Academy Press). 1980, 52: 413.
Graves Hoyt, William. Crawford Jr., Bryce; McEuen, Caroline K. , 編. Vesto Melvin Slipher. Biographical Memoirs of the National Academy of Sciences of the United States of America (National Academy Press). 1980, 52: 414.
Graves Hoyt, William. Crawford Jr., Bryce; McEuen, Caroline K. , 編. Vesto Melvin Slipher. Biographical Memoirs of the National Academy of Sciences of the United States of America (National Academy Press). 1980, 52: 415.
Graves Hoyt, William. Crawford Jr., Bryce; McEuen, Carolina K. , 編. Vesto Melvin Slipher. Biographical Memoirs of the National Academy of Sciences of the United States of America (National Academy Press). 1980, 52: 414.
Graves Hoyt, William. Crawford Jr., Bryce; McEuen, Caroline K. , 編. Vesto Melvin Slipher. Biographical Memoirs of the National Academy of Sciences of the United States of America (National Academy Press). 1980, 52: 414–415.
Slipher first reports on the making the first Doppler measurement on September 17, 1912 in The radial velocity of the Andromeda Nebula （頁面存檔備份，存於網際網路檔案館） in the inaugural volume of the Lowell Observatory Bulletin, pp. 2.56–2.57. In his report Slipher writes: "The magnitude of this velocity, which is the greatest hitherto observed, raises the question whether the velocity-like displacement might not be due to some other cause, but I believe we have at present no other interpretation for it." Three years later, Slipher wrote a review in the journal Popular Astronomy, Vol. 23, pp. 21–24 Spectrographic Observations of Nebulae （頁面存檔備份，存於網際網路檔案館）, in which he states, "The early discovery that the great Andromeda spiral had the quite exceptional velocity of -300 km(/s) showed the means then available, capable of investigating not only the spectra of the spirals but their velocities as well." Slipher reported the velocities for 15 spiral nebula spread across the entire celestial sphere, all but three having observable "positive" (that is recessional) velocities.
