Var Lundmark först att bevisa universums expansion? En insändare i Nature 10 oktober 2012 noterade att Knut Lundmark sannolikt var den allra förste att konkret bevisa universums expansion, 1924 – tre år före George Lemaitres beräkningar, fem år innan Edwin Hubble tog åt sig äran.
Genom NASA/IPAC/Extragalactic Database of Galaxy Distances, Pasadena, har Ian Steer kunnat slå fast:
"- – - measurements by a Swedish astronomer, Knut Lundmark, were much more advanced than formerly appreciated. Lundmark was the first person to find observational evidence for expansion, in 1924 – - - Lundmark’s extragalactic distance estimates were far more accurate than Hubble’s, consistent with an expansion rate (Hubble constant) that was within 1% of the best measurements today. "
Skälet till att Lundmarks mätningar inte godkändes rakt över var att hans metod byggde på galaxernas skenbara diametrar "cross-checked with one unproven distance to the Andromeda galaxy, which was derived from a type Ia supernova observed in 1885 and mistaken for a normal nova (W. Huggins and W. F. Denning Nature 32, 465–466; 1885)".
Medan Lundmark var nästan helt rätt på det var Hubbles egen uppskattning av "Hubble-konstanten" 1929 fel uppåt väggarna. Ian Steer sammanfattar: " Lundmark established observational evidence that the Universe is expanding. Lemaître established theoretical evidence. Hubble established observational proof. "
Lundmark uppmätte radialhastigheterna för 44 galaxer gentemot deras förmodade avstånd, han utgick från att M31 (Andromedagalaxen) låg på 200 000 pc och jämförde därefter galaxernas skenbara storlekar och ljusstyrkor med M31. Som den försiktige general han alltid var fann han förhållandet mellan rödförskjutning och avstånd "not a very definite one".
I en annan rapport publicerad 1925, står denna förgripliga och historiska sammanfattning av Lundmark: "A rather definite correlation is shown between apparent dimensions and radial velocity, in the sense that the smaller and presumably more distant spirals have the higher space-velocity."
En israelisk astronom vid namn Giora Shaviv synade hela komplexet för några år sedan och noterade:
"Lundmark gave a table of distances and velocities of spiral nebula. He based his distances on a hypothetical parallax derived from total magnitude and apparent diameter under the assumption that the apparent angular dimensions and the total magnitude of the spiral nebula are only dependent on the distance which means they are standard candles. Lundmark claimed that An inspection of the table (of distances and velocities) will show that a computation of R (the radius of curvature of the universe) from the individual values of V (the velocity) it will give inconsistent values for the radius of curvature. However, no details were given.
► Next, Lundmark calculated that: Plotting the radial velocities against these relative distances, we find that there may be a relation between the two quantities, although not very definite one. If this phenomenon were due to the curvature of space-time, we could derive the mean linear distance or determine the scale of our relative distance. We took Lundmark’s data for the 43 spiral nebulae at face value, ignored the data for the Globular Clusters and assumed the existence of a linear relation, and calculated the Hubble constant to be 71.2 ± 55.6km/sec per M pc, a values extremely close to present day accepted value(!) but with a large uncertainty.
► Lundmark, on the other hand, obtained much larger numbers and consequently argued that the simplified formula is not justified in this case. Lundmark erred by lumping the globular clusters and the spiral nebula though he admitted that this lumping certainly is open to objection.
► Lundmark’s method gave much larger distances for the nebulae and consequently smaller Hubble constant. Evidently, Lundmark had a blind date with destiny and missed it."
En kritisk Allan Sandage ("Lundmark´s shot in the foot"), och en till Lundmark positiv Sidney van der Berg m fl har synat historien tidigare. Lundmark var snubblande nära gåtans lösning, den saken verkar klar.
IAU bestämde sig med överväldigande majoritet 2018 för att Hubble-lagen ska omformuleras till "The Hubble–Lemaître law". Numera bör den kallas "The Lundmark-Lemaître-Hubble law".
