Dark matter hits you once a minute
Weakly Interacting Massive Particles (WIMPS) hit you about once a minute, according to a new paper titled Dark Matter collisions with the Human Body. That’s not something to be unduly worried about, as the paper suggests billions of WIMPs pass through our bodies every minute without so much as nudging a particle. That they do so …
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I am not a physicist, but...
I thought the whole point of Dark Matter was that we didn't know what it is?
Thus it should be impossible to say it hits us once a minute? It could hit us N times a minute, and the whole point of it being weakly interacting means it would make bugger-all difference, right?
So how does the number once a minute come up? It sounds suspiciously round to me, why not 3.1415 times a minute?
And surely a better standard could be used, say DM / ZD (Dark Matter particles per Zooey Deschanel - the voulme occupied by her at least)
Re: I am not a physicist, but...
Dark matter is simply something that cannot be trivially observed, as it only interacts via gravity and perhaps the weak force. We can observe its effects, and one day we'll know what it is made of, too (or find some other explanation for its effects). It is not simply defined as 'stuff we don't know about'.
Weak force interactions could potentially be measured, given a suitable tool. The rate of such interactions would be more or less proportional to the cross sectional area of the nuclei in the material the detector was made of and the density of that material; it woudl then be pretty trivial to scale that according to the average density, cross sectional area and composition of a human being to come up with a fairly useless number estimating the number of WIMP interaction in a given period of time.
1 per minute is a little suspiciously round, but seeing as the number is of supreme uselessness there's no need to give any sort of precision.
Re: I am not a physicist, but...
10^5 WIMPs hit a human body over the course of a year.
525960 minutes in a year.
Works out to just over one WIMP hitting you every five minutes.
Looking forward
to the Daily Mail article explaining how this causes/cures various cancers.
Re: Looking forward
Actually it could theoretically cause cancer. If it transfers momentum to a nucleus, that might kick the nucleus and its atom out of whatever molecule it's a part of. Which if it's just the wrong molecule might be enough to trigger cancer.
But it sounds like much less than the background radiation that you get anyway, so unlikely to be much of a problem.
Re: Looking forward
... to the Daily Express blaming this for the death of Diana...
Pretty bizarre
No-one has ever confirmed a single WIMP and the LHC has shown nothing so far.
Better talk about neutrinos.
Human Body Mass
If you eat too many burgers you increase your mass and therefore the chance of a collision.
In effect you become more WIMPEY.
Re: Human Body Mass
Or a Big Matter Accumulating Commentard.
I for one...
Would like to welcome our weakly interacting, overeating overlords..
Re: It's those damn photino birds
Call the xeelee! Oh, wait... better not.
Is it what i think it is?
I'm sure i read somewhere it was that packing material that all those scientific measurement apparatus was packed in?.....could be wrong!
When I was a 'younger' IT bod, WIMPs stood for Windows Icons Mice & Pointers.
Overall, I think I'd rather be hit by the dark matter type.
Mass of everything
So if....
- dark matter is making up 90% of all the known universe, we calculate this because gravitational interactions of the universe show a much more massive universe than we can otherwise explain through observation. So dark matter has mass and interacts with/through gravity. That implies that here on Earth dark matter particles that have mass will interact with Earth's gravitational field and therefore have weight.
- dark matter is distributed around the whole universe, including, right here right now, myself having billions of WIMPS stream through me without touching (so, presumably, huge amounts of WIMPS would be constantly streaming through every earthly object)
...so does it follow that dark matter is contributing to the mass of every object and person etc in the world?
If dark matter is evenly distributed around the universe by volume, we would have already detected it because instead of atomic weights being neat multiples of each other (H, 2H, 3H etc with H being mass of Hydrogen), they would be (X+H, X+2H, X+3H etc with X being dark matter mass). If dark matter is randomly distributed AND has an effect on mass we would never be able to measure a consistent mass. If dark matter is distributed among other particles according to the other particles' masses, we would not have previously detected it as all masses would be scaled up proportionately (XH, X2H, X3H etc). This is also not possible because if that were the case, we would have factored in the dark matter mass in our 'observed mass' calculations, and never noticed there was any dark matter in the first place.
Since none of these possibilities seem remotely likely, the conclusion is that even if I have a million tons of dark matter particles whizzing through me, they have no effect on my mass / weight. But that would mean that dark matter has no detectable gravitic effect here on earth but we can still detect the aggregate dark matter mass through it's effects on gravity.
Whichever way I look at it, my mind is well and truly boggled.
Re: Mass of everything
The clue's in the name. Since WIMPS interact with ordinary matter only weakly you can't weigh them. (They'd pass right through any scale). Indeed so far we can't measure them in any way. Ergo they can't affect any measurements of mass. The only way we know of their existence is through their contribution to gravitational effects at very large scales. As to why their gravitational effect is not apparent at smaller scales - well you have to remember that that matter in the universe is near to non-existent. O.K. maybe not non-existent, but on average the universe approximates a pretty good vacuum. Assuming dark matter is not clumpy like ordinary matter (i.e. that WIMPS don't strongly interact with anything including themselves) space with WIMPS in it is effectively just space but very slightly less tenuous. It's net effect on anything on a human scale is going to be zero.
Of course, anything that anyone says about dark matter is ,of necessity, highly speculative but the basic idea is actually pretty straightforward.
Better WIMPs than MACHOs
MACHOs (MAssive Cold Halo Objects) are another proposed source of dark matter: orphan planets and other regular material that is simply too cold to see easily. Being hit by an orphan planet would be a once in a lifetime experience.
Therefore: as below, so above: Being hit by a macho is worse than being hit by a wimp.
I won't be in to work today
as I've been hit by a shower of WIMPs
I won't be in to work ever
as I've been hit by a shower of MACHOs
Science?
Can this hypothesis be falsified? Or even observed? If not there there is no proof and without proof you don't have science, you have one of those "P" subjects.
maybe all the mass
is outside the bit we can see and is stil laccelerating pulling us along with it until we die a cold sad death..
does shroedingers cat know how big the universe is outside his box? does he care? what is that funny contraption in the cor...
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