 | | | 
19.10.2007, 09:56
|  | Forum Veteran | | Join Date: Jan 2007 Location: somewhere, USA
Posts: 1,347
Groaned at 41 Times in 37 Posts
Thanked 950 Times in 459 Posts
| | Ask a Scientist
Okay, I'm gonna try this out. Any burning science questions that people would like answered, hopefully me and the other scientists on the forum can answer.
But remember, I'm a chemist, I'm not omniscient. I'll do my best. | 
19.10.2007, 09:58
| Junior Member | | Join Date: Sep 2007 Location: Lausanne
Posts: 50
Groaned at 0 Times in 0 Posts
Thanked 0 Times in 0 Posts
| | Re: Ask a Scientist
Hi-
I can help in the field of molecular biology
| 
19.10.2007, 10:03
| Forum Legend | | Join Date: Dec 2006 Location: Zurich
Posts: 4,967
Groaned at 186 Times in 121 Posts
Thanked 8,679 Times in 2,902 Posts
| | Re: Ask a Scientist
Great idea for a thread!
Since Psychology gets classed as a science - ask away!
But I have one for Chemgoddess:
When you mix Maizena with a certain quantity of water, it has this weird quality of feeling hard and liquid at the same time (try it, you'll be playing for hours, great for kids). Now I'm not sure how to Google this so my question is - how does that work?
| 
19.10.2007, 10:17
|  | Forum Veteran | | Join Date: Jul 2007 Location: Lörrach/DE
Posts: 644
Groaned at 6 Times in 6 Posts
Thanked 568 Times in 294 Posts
| | Re: Ask a Scientist
This one is a job for the chemical engineer... sorry chemgodess, you can have the next one
A cornstarch solution is a type of non-Newtonian fluid, a fluid whose viscosity changes with shear.
In the case of a mixture of cornstarch and water, the viscosity increases with the shear rate - so it gets harder the more you stir. This is known as a dilatant material.
The opposite (viscosity decreases with shear) is a pseudoplastic material. A common example of this is tomato sauce - we all know how hard is getting that stuff out of a bottle, but once it starts moving, you can't stop it.
| 
19.10.2007, 10:28
|  | Forum Legend | | Join Date: Jun 2006 Location: Züri
Posts: 7,553
Groaned at 164 Times in 105 Posts
Thanked 8,424 Times in 3,486 Posts
| | Re: Ask a Scientist
If the Universe is expanding, where or what is it expanding into?
I've seen an episode of Heroes and want to develop my ESP. Any tips?
One more: why doesn't the Earth's gravitational force provide / allow a constant law regarding hydrodynamics?  It's complicated and I need an idiots guide. Thanks for any feedback.
| 
19.10.2007, 10:33
|  | Forum Veteran | | Join Date: May 2007 Location: Liechtenstein
Posts: 703
Groaned at 2 Times in 2 Posts
Thanked 503 Times in 274 Posts
| | Re: Ask a Scientist | Quote: | |  | | | This one is a job for the chemical engineer... sorry chemgodess, you can have the next one
A cornstarch solution is a type of non-Newtonian fluid, a fluid whose viscosity changes with shear.
In the case of a mixture of cornstarch and water, the viscosity increases with the shear rate - so it gets harder the more you stir. This is known as a dilatant material.
The opposite (viscosity decreases with shear) is a pseudoplastic material. A common example of this is tomato sauce - we all know how hard is getting that stuff out of a bottle, but once it starts moving, you can't stop it. | | | | | The word which describes these processes is nice. Try to fit it into daily conversation: thixotropy or thixotropic
| 
19.10.2007, 10:33
|  | Forum Veteran | | Join Date: Feb 2007 Location: back in Zurich (but pining for Brussels periodically)
Posts: 894
Groaned at 5 Times in 5 Posts
Thanked 622 Times in 320 Posts
| | Re: Ask a Scientist
I have one: You're boiling water to cook pasta. When the water gets hot enough to add oil and salt, why does the water start boiling like crazy right when you add the salt?
(someone said there are no dumb questions)
| 
19.10.2007, 10:34
| Forum Legend | | Join Date: Dec 2006 Location: Zurich
Posts: 4,967
Groaned at 186 Times in 121 Posts
Thanked 8,679 Times in 2,902 Posts
| | Re: Ask a Scientist | Quote: | |  | | | This one is a job for the chemical engineer... sorry chemgodess, you can have the next one
A cornstarch solution is a type of non-Newtonian fluid, a fluid whose viscosity changes with shear.
In the case of a mixture of cornstarch and water, the viscosity increases with the shear rate - so it gets harder the more you stir. This is known as a dilatant material.
The opposite (viscosity decreases with shear) is a pseudoplastic material. A common example of this is tomato sauce - we all know how hard is getting that stuff out of a bottle, but once it starts moving, you can't stop it. | | | | | Woooow *think wow like those little green alien toys did in Toy Story II*, I feel like my IQ has just gone up five points.
As for the universe, that's a tough one, as there is actually nothing outside of the universe. I find this totally unfathomable and explain this shortcoming with the fact, that my brain has boundaries given by the skull it lives in.
But if you want a really good explanation for that, I recommend Bill Bryson's Short History of Nearly Everything, also available as an audiobook and a brilliant read for people who like simple explanations for complex things.
| 
19.10.2007, 10:34
|  | Member | | Join Date: Jun 2007 Location: Australia
Posts: 135
Groaned at 0 Times in 0 Posts
Thanked 14 Times in 11 Posts
| | Re: Ask a Scientist
Brilliant idea for a thread. Will have to ask some of my nuclear physics friends if they have any decent questions to ask!! | 
19.10.2007, 10:38
| Forum Legend | | Join Date: Dec 2006 Location: Zurich
Posts: 4,967
Groaned at 186 Times in 121 Posts
Thanked 8,679 Times in 2,902 Posts
| | Re: Ask a Scientist
Apparently, for physicists, physics is the only science, everything else is just stamp collecting. | 
19.10.2007, 10:44
|  | Forum Legend | | Join Date: Jun 2006 Location: Züri
Posts: 7,553
Groaned at 164 Times in 105 Posts
Thanked 8,424 Times in 3,486 Posts
| | Re: Ask a Scientist
Thanks Kittster. I understood there's no evidence suggesting there's anything beyond the Universe, but you seem to have insider knowledge
And before the Physicists get all heady, remember Philosophy is the Mother of all Science
Who am I?
Why am I here?
What's it all about..?
Last edited by Uncle Max; 19.10.2007 at 10:51.
Reason: Philosophers aren't expected to spell...
| 
19.10.2007, 10:54
|  | Forum Legend | | Join Date: Jun 2006 Location: Züri
Posts: 7,553
Groaned at 164 Times in 105 Posts
Thanked 8,424 Times in 3,486 Posts
| | Re: Ask a Scientist | Quote: | |  | | | I have one: You're boiling water to cook pasta. When the water gets hot enough to add oil and salt, why does the water start boiling like crazy right when you add the salt?
(someone said there are no dumb questions) | | | | | Salt causes the water to boil quicker, that's why. Add it before it boils, and save a few Rappen / Cents from your electricity bill. Remember to stir, though, as salt also corrodes.
Don't bother adding oil, it's useless. Use more water instead - hence deep pasta pans | 
19.10.2007, 10:59
|  | Forum Veteran | | Join Date: Jan 2007 Location: somewhere, USA
Posts: 1,347
Groaned at 41 Times in 37 Posts
Thanked 950 Times in 459 Posts
| | Re: Ask a Scientist
That's not a dumb question at all, actually a quite interesting one and not trivial at all.
So when we think about what happens when water boils. You have liquid water getting heated up enough that it has enough energy to go from the liquid to the gas phase, a phase transition. Nucleation is the term for a phase transition that occurs in small region. The spots on your pot where see the tiny bubbles at the bottom of soon to be boiling water, could be considered nucleation sites, you have some water molecules trying to go from liquid to gas. Nucleation is a pretty difficult, not fully understood concept but it tends to happen on surfaces. Generally your pot is pretty smooth so there aren't a bunch of nucleation sites but eventually your liquid to gas bubbles grow bigger, and your gaseous water gets enough energy to break free.
But as I said previously nucleation sites occurs on surfaces, when you add salt you add a whole bunch of little tiny places where your water can undergo it's phase transition and hence it all starts going to the gas phase, i.e., boiling all at once.
It's kinda the same phenomena as the mento's/diet coke explosion. When you put in the rough surfaced mento, all the CO2 dissolved in the soda has a ton of new nucleation sites and hence can fly outta the bottle, i.e., outgas.
Hope that makes sense. | Quote: | |  | | | I have one: You're boiling water to cook pasta. When the water gets hot enough to add oil and salt, why does the water start boiling like crazy right when you add the salt?
(someone said there are no dumb questions) | | | | |
__________________ Everyone needs to believe in something, I believe I'll have another drink.
Last edited by chemgoddess; 19.10.2007 at 11:15.
Reason: typo
| 
19.10.2007, 11:00
|  | Forum Veteran | | Join Date: Jan 2007 Location: somewhere, USA
Posts: 1,347
Groaned at 41 Times in 37 Posts
Thanked 950 Times in 459 Posts
| | Re: Ask a Scientist
Actually, if you add the salt before, it raises the boiling point of water, so it would take longer to boil. Please see above post for explaination. | Quote: | |  | | | Salt causes the water to boil quicker, that's why. Add it before it boils, and save a few Rappen / Cents from your electricity bill. Remember to stir, though, as salt also corrodes.
Don't bother adding oil, it's useless. Use more water instead - hence deep pasta pans  | | | | | | 
19.10.2007, 11:08
|  | Senior Member | | Join Date: Apr 2007 Location: Arni, AG
Posts: 325
Groaned at 0 Times in 0 Posts
Thanked 178 Times in 83 Posts
| | Re: Ask a Scientist | Quote: | |  | | | Actually, if you add the salt before, it raises the boiling point of water, so it would take longer to boil. Please see above post for explaination. | | | | | That's true, but from what I understand in order for salt to affect the boiling point of water in a pot in any noticeable way, one would have to add so much salt to the water that it would make anything boiled in it unpalatable.
Of course, I'm no chemist.
| 
19.10.2007, 11:10
|  | Forum Veteran | | Join Date: Jan 2007 Location: somewhere, USA
Posts: 1,347
Groaned at 41 Times in 37 Posts
Thanked 950 Times in 459 Posts
| | Re: Ask a Scientist
Yes, in a noticable way. But that still doesn't detract from the fact that salt raises the boiling point of water as a rule. And of course you'd have to consider how much and what type of trace minerals are in your water, etc. etc. | Quote: | |  | | | That's true, but from what I understand in order for salt to affect the boiling point of water in a pot in any noticeable way, one would have to add so much salt to the water that it would make anything boiled in it unpalatable.
Of course, I'm no chemist. | | | | | | 
19.10.2007, 11:17
|  | Forum Veteran | | Join Date: Feb 2007 Location: back in Zurich (but pining for Brussels periodically)
Posts: 894
Groaned at 5 Times in 5 Posts
Thanked 622 Times in 320 Posts
| | Re: Ask a Scientist
I love this thread - great idea of the scientists' part!
Does anybody watch Die Sending mit der Maus on German TV Sundays? They do cool explanations for things too, although there's no particular focus on science there.
| 
19.10.2007, 11:19
|  | Senior Member | | Join Date: Apr 2007 Location: Arni, AG
Posts: 325
Groaned at 0 Times in 0 Posts
Thanked 178 Times in 83 Posts
| | Re: Ask a Scientist | Quote: | |  | | | If the Universe is expanding, where or what is it expanding into? | | | | | Technically, the answer is "nothing". I guess it depends on which theory du jour you subscribe. Hyperspace theory claims that the instant before the big bang, a 10-dimension space decayed into 2 "pieces", of which:
1) one piece expanded into an infinite 4-dimension macro space in which our universe is expanding
2) the other piece contracted/collapsed into an infinitesimal 6-dimension space about the size of the Planck length.
Last edited by bozothedeathmachine; 19.10.2007 at 11:21.
Reason: Spelling
| 
19.10.2007, 11:35
|  | Forum Veteran | | Join Date: Jul 2007 Location: Lörrach/DE
Posts: 644
Groaned at 6 Times in 6 Posts
Thanked 568 Times in 294 Posts
| | Re: Ask a Scientist | Quote: | |  | | | I love this thread - great idea of the scientists' part!
Does anybody watch Die Sending mit der Maus on German TV Sundays? They do cool explanations for things too, although there's no particular focus on science there. | | | | | That is a fantastic show (from your avatars, you are clearly also a fan). No matter how old you are, there is something to learn here. The way that they are able to explain complicated things in a way that even pre-schoolers can understand it is commendable. Reminds me of the good ol' Curiosity Show we had in Australia when I was little.
| 
19.10.2007, 11:49
|  | Forum Veteran | | Join Date: Jan 2007 Location: Zurich
Posts: 572
Groaned at 0 Times in 0 Posts
Thanked 174 Times in 108 Posts
| | Re: Ask a Scientist
Here's a social psychology question: how do people instinctively know when they are being looked at? Or is it a myth?
|
Currently Active Users Viewing This Thread: 1 (0 members and 1 guests) | | Thread Tools | | Display Modes | Linear Mode |
Posting Rules
| You may not post new threads You may not post replies You may not post attachments You may not edit your posts HTML code is Off | | | All times are GMT +2. The time now is 22:39. | |