3 ms·

Lorenz (one of the co-authors of this piece) has disproven his previous theory--that the rocks were temporarily embedded in a slab of ice which then floated. [1

by IvyMike 12y ago

Lorenz (one of the co-authors of this piece) has disproven his previous theory--that the rocks were temporarily embedded in a slab of ice which then floated. [1] I mean, I know that's how science is supposed to work, but in these days of politicized everything it's cool to see someone say "new data disproves my previous hypothesis" and continue working to find the real truth. [1] http://www.livescience.com/37492-sailing-stones-death-valley-moving-rocks.html http://www.livescience.com/37492-sailing-stones-death-valley...

lotsofmangos 12y ago
To be fair, people saying "new data disproves my previous hypothesis" is how science does work, day in, day out. If you can find a working experimental scientist who has never done that, then they are either absurdly lucky or a charlatan.
wdr1 12y ago
I like to believe this happens fairly often. It's just in the heavily politicized fields it becomes toxic to say "I was wrong." Another reason I like to keep politics away from science.
pasiaj 12y ago
I thought this did not disprove the previous theory. It just refined it, showing that it can be a 'sheet' of ice instead of a 'slab'. I read about his theory about a year ago, and it described thin sheets of ice then, also.
- pionar 12y ago
  I think the previous theory was that ice formed under the rocks, then the rocks slid on that ice. I heard him on NPR this morning, and he said that the sheets of ice are like tugboats, pushing the rocks instead of carrying them.
- sbhere 12y ago
  It may not have "disproved" it, but he appears to have discarded his original hypothesis. From linked article: > Floating ice may sometimes be ineffective at moving rocks since stones with low profile may be over-ridden by floating ice; rocks at the edges of ice panels may fail to sufficiently engage with floating ice to be moved, and rocks may be too massive for the available force (Fig. 8d). > A surprise is the thinness of ice involved in rock movement. Ice sheets 3–6 mm thick are insufficient to float rocks off the playa surface, as proposed in some models [8], [11], and, in any case, we observed that ice melts first around rocks. However, moving sheets of ice tens of meters in extent but only a few millimeters thick are clearly effective at moving rocks in their path. Forces on stones increase when multiple sheets of ice pile on the upstream side of a rock and increase the effective surface area of the rock exposed to stresses of wind and flowing water (Fig. 8a). Author's 2011 publication (citation #11): > 11. Lorenz RD, Jackson BK, Barnes JW, Spitale J, Keller JM (2011) Ice rafts not sails: Floating the rocks at Racetrack Playa. American Journal of Physics 79: 37–42. doi: 10.1119/1.3490645 Abstract: >> We suggest that the existence of many of the rock-carved trails at Racetrack Playa in Death Valley National Park is predominantly due to the effect of arbitrarily weak winds on rocks that are floated off the soft bed by small rafts of ice, as also occurs in arctic tidal beaches to form boulder barricades. These ice cakes need not have a particularly large surface area if the ice is adequately thick—the ice cakes allow the rocks to move by buoyantly reducing the reaction and friction forces at the bed, not by increasing the wind drag. The parameter space of ice thickness and extent versus rock size for flotation is calculated and found to be reasonable. We demonstrate the effect with a simple experiment. Perhaps if you were reading something 1yr ago, it was in correlation to this new hypothesis, but this 2014 publication sits contrary to the 2011 publication.

by IvyMike 12y ago

lotsofmangos 12y ago

To be fair, people saying "new data disproves my previous hypothesis" is how science does work, day in, day out. If you can find a working experimental scientist who has never done that, then they are either absurdly lucky or a charlatan.

wdr1 12y ago

I like to believe this happens fairly often. It's just in the heavily politicized fields it becomes toxic to say "I was wrong." Another reason I like to keep politics away from science.

pasiaj 12y ago

I thought this did not disprove the previous theory. It just refined it, showing that it can be a 'sheet' of ice instead of a 'slab'. I read about his theory about a year ago, and it described thin sheets of ice then, also.

pionar 12y ago
I think the previous theory was that ice formed under the rocks, then the rocks slid on that ice. I heard him on NPR this morning, and he said that the sheets of ice are like tugboats, pushing the rocks instead of carrying them.
sbhere 12y ago
It may not have "disproved" it, but he appears to have discarded his original hypothesis. From linked article: > Floating ice may sometimes be ineffective at moving rocks since stones with low profile may be over-ridden by floating ice; rocks at the edges of ice panels may fail to sufficiently engage with floating ice to be moved, and rocks may be too massive for the available force (Fig. 8d). > A surprise is the thinness of ice involved in rock movement. Ice sheets 3–6 mm thick are insufficient to float rocks off the playa surface, as proposed in some models [8], [11], and, in any case, we observed that ice melts first around rocks. However, moving sheets of ice tens of meters in extent but only a few millimeters thick are clearly effective at moving rocks in their path. Forces on stones increase when multiple sheets of ice pile on the upstream side of a rock and increase the effective surface area of the rock exposed to stresses of wind and flowing water (Fig. 8a). Author's 2011 publication (citation #11): > 11. Lorenz RD, Jackson BK, Barnes JW, Spitale J, Keller JM (2011) Ice rafts not sails: Floating the rocks at Racetrack Playa. American Journal of Physics 79: 37–42. doi: 10.1119/1.3490645 Abstract: >> We suggest that the existence of many of the rock-carved trails at Racetrack Playa in Death Valley National Park is predominantly due to the effect of arbitrarily weak winds on rocks that are floated off the soft bed by small rafts of ice, as also occurs in arctic tidal beaches to form boulder barricades. These ice cakes need not have a particularly large surface area if the ice is adequately thick—the ice cakes allow the rocks to move by buoyantly reducing the reaction and friction forces at the bed, not by increasing the wind drag. The parameter space of ice thickness and extent versus rock size for flotation is calculated and found to be reasonable. We demonstrate the effect with a simple experiment. Perhaps if you were reading something 1yr ago, it was in correlation to this new hypothesis, but this 2014 publication sits contrary to the 2011 publication.