Hyperdimensional water

[Dave5N]

Yeah. ~I see.

 

[Chuffy]

Yeah. ~I see.

You're in a feisty mood this evening Dave! Has Nena grown her armpits back or summat?

 

[Dave5N]

Yokel

 

[Chuffy]

Yokel

Look, you're the one with a crush on Arbitrarararary.

 

[Pete]

Heavy water (containing the heavy isotope of hydrogen, deuterium, in place of ordinary hydrogen: it is not 'heavy' in other senses) is significant in the nuclear industry because the deuterium nuclei, whilst having almost the same effectiveness as ordinary protons in their ability to 'moderate' the neutron flux, have far lower absorption cross-section for thermal neutrons. Typically about 0.0005 barns for deuterons, as compared to 0.33 barns for protons. Absorption of thermal neutrons is a significant factor in loss of efficiency in nuclear reactors.

 

[biking_fox]

it is not 'heavy' in other senses

pedantic argument. It is 19g/mol instead of 18g for ordinary water so it is very slightly heavier. (could be 20g/mol if full deuterated?)

I don't know the density of deuterated water but assume it must be very slightly more than ordinary water - after all there is more stuff in the same space??

 

[cisamcgu]

pedantic argument. It is 19g/mol instead of 18g for ordinary water so it is very slightly heavier. (could be 20g/mol if full deuterated?)

I don't know the density of deuterated water but assume it must be very slightly more than ordinary water - after all there is more stuff in the same space??

<even more pedantic> Surely it would therefore be dense water rather than heavy water ?</even more pedantic>

 

[Pete]

pedantic argument. It is 19g/mol instead of 18g for ordinary water so it is very slightly heavier. (could be 20g/mol if full deuterated?)

I don't know the density of deuterated water but assume it must be very slightly more than ordinary water - after all there is more stuff in the same space??

http://en.wikipedia.org/wiki/Heavy_water

OK then. Slightly more dense at 1.1g/ml. Significantly different physical and chemical properties - it appears to be actually poisonous to drink (not something I remember learning in the physics course). Pretty expensive. I've never had a bottle of heavy water in my hands, let alone drunk it - it was all theory stuff for me.

 

[Arch]

I think I remember being taught that as the level of deuterium ('heavy hydrogen') in the atmosphere varies with temperature, the detection of heavy water in ice cores is how temperature records of the past are compiled...

 

[biking_fox]

Arch - yep Not just deuterium but rare isotopes of Oxygen as well. However it all gets very very tricky as the temperature changes in one direction lots of different mechanisms* act, some of which increase the isotope ratio and some of which decrease it. Working out which was the dominent mechanism at the time concerned is not simple - one of the many reasons why we don't have absolute answers as to what the past climate was.

Some examples
*assume it was colder long ago:
Ie more ice - Heavy water freezes slightly more easily than light therefore more heavy water in ice than now. BUT it doesn't evaporate as easily hence more light water in rain (which leads to ice) than now etc etc etc.

 

[Arch]

Arch - yep Not just deuterium but rare isotopes of Oxygen as well. However it all gets very very tricky as the temperature changes in one direction lots of different mechanisms* act, some of which increase the isotope ratio and some of which decrease it. Working out which was the dominent mechanism at the time concerned is not simple - one of the many reasons why we don't have absolute answers as to what the past climate was.

Some examples
*assume it was colder long ago:
Ie more ice - Heavy water freezes slightly more easily than light therefore more heavy water in ice than now. BUT it doesn't evaporate as easily hence more light water in rain (which leads to ice) than now etc etc etc.

Glad I remembered right - not my specialism, but we got a very intersting talk from an expert. I remember him saying that more detailed study now suggests that past flips between ice age and warm could have happened much faster than previously thought. Like, decades.

 

[mr_hippo]

If a very large cube is made up of nine smaller cubes, you end up with 27 dimensions, each of the nine cubes having three dimensions.

No, it will only have three dimensions - length, width and height. You cannot make a cube using nine smaller cubes - the minimum that you need is 27 smaller cubes.
If we count speed/time as a dimension, what are the other 23 dimensions?

 

[Pete]

I seem to remember some beast called a tesseract which was an extension of the cube into four dimensions - four space-like dimensions that is, not our familiar space-time as a 4-dimensional Einsteinian space in which the time-dimension has different properties to the other three...

Basically you start with eight cubes in 3-space and 'fold' them in some incomprehensible way into this fictitious 4-space. Don't ask me how, nor what the end-result 'looks' like! I have seen a model 'projection' of a tesseract into 3-space - basically two cubes slightly displaced with wires joining the vertices.

 

[Graham O]

Just to throw another spanner into this thread, I once ordered some dilute water! Something which always gets a non-chemist puzzled.

 

[Chuffy]

Just to throw another spanner into this thread, I once ordered some dilute water! Something which always gets a non-chemist puzzled.

How about dehydrated water? It would be much lighter to carry. If we can send a man to the moon....etc