Wikipedia:Reference desk/Archives/Science/2016 November 7

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November 7

Are there any dinosaur museums in BC?

I would like to see some dinosaur fossils. Drumheller in Alberta is kinda far. Swancat (talk) 01:55, 7 November 2016 (UTC)

Type into Google "British Columbia dinosaur museum", and a number of links come up. Loraof (talk) 02:37, 7 November 2016 (UTC)

The Royal British Columbia Museum in Victoria, British Columbia, has a collection of paleontology specimens - the listing of dinosaur fossils is pretty short, but bear in mind that those are authentic specimens, not bronze- or plaster- or plastic-resin casts.

If you're looking for big exhibition halls, in the style of the Field Museum's famous T. rex, it looks like you'll have to travel farther afield.

Nimur (talk) 15:46, 7 November 2016 (UTC)

If you're close to the US border (as many in BC are), you might consider the Burke Museum in Seattle: [1]. StuRat (talk) 18:21, 7 November 2016 (UTC)

• Based on this user's self-description, geolocation, and interests, she is almost certainly the universally banned User:Neptunekh and I plan to file a checkuser ASAP. μηδείς (talk) 06:57, 8 November 2016 (UTC)

How accurate is the Einstein’s light clock?

A light clock consists of two mirrors / plates in between which a pulse of light is back and forth. A photon doesn’t have acceleration as it always travels at light speed "c" in vacuum from the moment of its creation but a pulse has to halt before it changes its direction (reflected) or be absorbed and re-emitted back. Thus how does a photon (either in particle or wave form) maintain its speed “c” continuously in the light clock during this transit period and what would be its effect on time dilation?2001:56A:7399:1200:433:A9AD:63FC:B7CB (talk) 20:38, 7 November 2016 (UTC)eek

Here is an explanation of the light clock which brings up some of the more practical aspects of it. Specifically, in this case, this was not ever intended to be a real clock one would build, instead it seems to have been intended as one of Einstein's Gedankenexperiments utilizing an idealized reflective surface rather than any true mirror made of out real material; in physics this is known as the spherical cow approximation, or sometimes a Fermi estimate. In other words, Einstein isn't proposing you build such a clock, merely to consider the implications for the nature of light could you actually build such a clock (which may or may not be actually possible). --Jayron32 20:50, 7 November 2016 (UTC)

Think you will find that his description of a light clock was a simple analogy to make his theorem easier to understand. It was not meant to describe a practical clock. --Aspro (talk) 20:55, 7 November 2016 (UTC)

As an aside. A friend who works at the NPL told me that they now have a 'clock' that is so accurate, that from the time of the big-bang, there would only be one second adrift between the two (which equates to something like 10¹⁸. So asked him which is out by this 'second' since the dawn of creation. The NPL clock or the universe? Took a good minute of a complex explanation before he realized I asked with my tongue in cheek. Yet think about it. Modern atomic clocks are so stable that to take such a clock on vacation it will show a different time. Place one on the International Space Station and the gravitational effect of the earth, moon and sun will effect its time keeping.--Aspro (talk) 21:24, 7 November 2016 (UTC)

Daniel Kleppner wrote an interesting article on this subject called "Time too good to be true". -- BenRG (talk) 19:03, 8 November 2016 (UTC)

Thanks for the replies – simplicity is fine but at least we can avoid broken chain in imagination, which creates discontinuity.

• ...but a pulse has to halt before it changes its direction... - no. Most likely, the reasoning behind this is Newton's second law, which says momentum is differentiable and in particular continuous and subject to the intermediate value theorem. But going from momentum to speed is only true under the assumption that a photon has a mass, which is probably false. Tigraan^{Click here to contact me} 08:48, 8 November 2016 (UTC)

fracking, Project Mohole

If scientists are worried that fracking could cause earthquakes, then could Project Mohole also have caused earthquakes, perhaps more severe or even volcanoes? — Preceding unsigned comment added by 144.35.45.82 (talk) 22:37, 7 November 2016 (UTC)

All Mohole extracted were cores (and chips) of the substrate they were drilling through. Fracking is different. To cause a volcano it would have needed to be perpendicular above a bloom. The Mohole Projects did not drill into this type of geology. There was little point in drilling in places like Yellowstone Park as they would have just hit magma. The project was to explore the transition between the crust and mantle. Err. what the WP article doesn’t mention is that the Soviet Union achieved it. So the article needs updating by several decades to counter Wikipedia:Systemic bias--Aspro (talk) 23:26, 7 November 2016 (UTC)

If you are thinking of the Soviet's Kola Superdeep Borehole, then that didn't reach the mantle either. It was substantially deeper than Mohole, but where it was drilled the crust was thicker so it still remained far from the boundary. As far as I know, no one has yet penetrated the boundary. Dragons flight (talk) 00:13, 8 November 2016 (UTC)

I've never actually been clear on that. Would drilling a small hole into a magma reservoir actually mean a volcano, or just a slow seep? Can a thin tunnel filled with magma melt itself to become wider, or would the cold just freeze the magma before it got far? Wnt (talk) 00:01, 8 November 2016 (UTC)

It is going to depend on the details. A low melting point, high gas content magma trapped beneath a layer of high melting point rock might well be able to push itself out if punctured by a borehole. However, I would guess that the appropriate physical conditions for such an event would be rare. In a more typical case, I would expect the magma to cool and plug the narrow borehole much more rapidly than it can be pushed out. Dragons flight (talk) 00:20, 8 November 2016 (UTC)

Really needs a volcanologist/petrologist to answer this. As I understand it: The overbearing rock (in a geological time frame) is like plasticine. It flexes and bends without cracking so won't let the magma escape until the upward pressure forces the magma through. Hypothetically speaking ( not theoretically speaking, because I don't think a testable theory has yet come about) a borehole may allow magma to enter the over-bearing rock. As magma has loads of H2O, hydrofluoric acid and other things, it would lower the melting point of the rock around the bore hole and thus widening it. Thus inducing a volcano. But it would require the magma to have upwards pressure (positive lithostatic pressure). However, it will not just spurt out of the drilling well head like an oil gusher. This may still take a few thousand years for the magma to break surface. I’m more than hopeful for a Earth Scientist to add to my off- the-top- of-my-head ramblings. It will also depend on the origin. Lava in many Pacific locations is thin and runny whereas the lava from the west coast of the US is thick with a different chemical composition.--Aspro (talk) 00:52, 8 November 2016 (UTC)

Definitely beyond my pay grade! a simple-minded notion of a hole would have it at a bit over atmospheric pressure, i.e. far less than any magma reservoir. But a real well usually (always?) has drilling mud to raise the pressure. But that mud isn't as dense as the rock, is it? So the pressure at depth might be ... less? Of course, mud and magma don't really mix... drilling into 300 C rock is apparently a technical feat only recently attempted according to one of those articles. I suppose though that drilling into magma or into oil have some common features, that a blowout is possible if the pressure isn't handled correctly. Wnt (talk) 02:15, 8 November 2016 (UTC)

Can't answer this by point -by-point yet just add other comments. As you say, drilling at 300 causes problems for the traditional bits, because steel looses it hardness at around these temperatures. So one has to employ tungsten carbide and industrial diamond teeth. Perhaps a bigger factor is, at these temperatures the lubricating grease and seals on the cutting head break down. Newer synthetic greases and seal materials has bumped that up to about 500 degrees now. Still a long way though, from being able to bore into the very hot rock immediately overbearing the magma – which is why I said this was purely hypothetical according to the current state of technology. The drilling mud should perform until it reaches the critical point of water, where regardless of how much pressure it is under, the water will become vapour. Oil based drilling mud is already used and Barium sulfate increases the density (after the Iraq War , barium sulfate was often injected into the ruptured well-heads in the Kuwait oil fields because it was so heavy, it could overcome the hydrodynamic forces of the crude gushing out). That density of mud and the flow rate brings the rock fragments up to the surface. In the future, new synthetic oil substitutes for water may over come this. A very high flow rate of cooled synthetic mud may also be able to cool the surrounding rock. All very easy to say but difficult to achieve in practice – and very expensive. The mud may be less dense than the rock but magma is viscous, so it is very unlikely to spurt out – unless it happens in Hollywood.--Aspro (talk) 14:47, 9 November 2016 (UTC)

Fracking involves injecting large quantities of water-based fluids under the Earth. Under the right conditions, those fluids can lubricate existing faults and transfer pressure in ways that allows earthquakes to occur. Deep exploratory drilling like Project Mohole doesn't involve the injection of pressurized fluids the way that fracking does, and so would be unlikely to trigger any faults in the area. Dragons flight (talk) 00:24, 8 November 2016 (UTC)

Here's an interesting article on what's been going on in Oklahoma recently.[2] ←Baseball Bugs ^{What's up, Doc?} carrots→ 03:42, 8 November 2016 (UTC)

The actual fracking appears to have at most a minor effect. However, fracking uses a great deal of water, which becomes nasty polluted water that must be disposed of. the industry disposes of it by re-injecting it into the ground, and these re-injection well are highly correlated with subsequent earthquakes. All of this happens in sedimentary rock, generally nowhere near any magma. -Arch dude (talk) 02:08, 9 November 2016 (UTC)