Ask a physicist anything. (7)

[Chalnoth]

Parhaps i should rephrase myself. Why do strong emotion trigger crying and people to shed tears? the answer of the first question is penalism! Penalism causes people not to shed tears when they are sad. usually!

What is it good for? this is parhaps one of those questions that has alot of answers i guess!

Ah, for that, well, I suspect that there is no real answer. The specific thing that we do to show emotion to others is entirely arbitrary. There is no meaning behind crying besides the meaning we impart on it. So likely it was just some accident of evolutionary history that was later amplified by selection. I'm not sure what that would have been, but the biological world is rife with all sorts of interesting behaviors to communicate all sorts of different things (such as dogs wagging their tail or growling).

 

[Lillen]

an advanced body language...

 

[Chalnoth]

an advanced body language...

Advanced? What do you mean by advanced, specifically?

 

[Lillen]

Something only humans do...

 

[Chalnoth]

Something only humans do...

I'm not sure that's actually true. It's generally not an easy thing to infer what internal emotional state various animals undergo. Other animals do certainly cry, but it's difficult to know why.

But why would that make it advanced in any event?

 

[hisgrace26]

Two main ones are eternal inflation and quantum vacuum fluctuations.

That's good. I'm learning something. Can you give me the quote or paragraph and source where it said that please?

 

[Chalnoth]

That's good. I'm learning something. Can you give me the quote or paragraph and source where it said that please?

Well, if you like, you can start reading up on eternal inflation here:
Inflation (cosmology) - Wikipedia, the free encyclopedia

One of my favorite ideas related to quantum fluctuations can be found here:
[hep-th/0410270] Spontaneous Inflation and the Origin of the Arrow of Time

Note that the ideas are actually extremely similar.

 

[pgp_protector]

Saw this in my Google+ stream, anyone have a translation ?

 

[ChristianT]

I can translate it for you (via Google Translate)

 

[pgp_protector]

I can translate it for you (via Google Translate)

doesn't work to well on images
(or I'm missing a new feature I didn't know about)

 

[ChristianT]

Forests to deserts in just 34 years

The NAsa photo was released this weekend with better resolution of the Earth in history. Compare to one of 1978, it's evident that the planet is deteriorating by leaps and bounds.

That's when you type it in manually!

 

[ChristianT]

Not sure if this is completely scientific or can be explained in such a way,

but

If an object (for humane purposes, say a rock) were to be shot or flung in any particular direction (for this question, let's assume straight up from the ground of earth) faster than it's terminal velocity, what would happen to the object? Would it disintegrate? Would air resistance, mass, or weight slow it down?

 

[Chalnoth]

Forests to deserts in just 34 years

The NAsa photo was released this weekend with better resolution of the Earth in history. Compare to one of 1978, it's evident that the planet is deteriorating by leaps and bounds.

That's when you type it in manually!

Yeah, that's kinda what I guessed.

It's a bit dishonest, because much of the US, particularly the southwest, is undergoing an especially strong drought right now. This drought may be partially attributed to global warming, but only partially. And it is going to get better before long.

 

[Chalnoth]

If an object (for humane purposes, say a rock) were to be shot or flung in any particular direction (for this question, let's assume straight up from the ground of earth) faster than it's terminal velocity, what would happen to the object? Would it disintegrate? Would air resistance, mass, or weight slow it down?

Well, unfortunately that depends upon a lot of things. Certainly being fired that fast from the surface of the Earth would be fast enough to heat up the atmosphere in front of it to the point that it is basically surrounded by a fireball. But then some rather complicated physics comes into effect on what would happen next. Some possibilities:

1. If the object is small, then there's a fair chance it will simply burn up before it is able to exit the atmosphere. Obviously the lower the angle of firing, the more likely this is to happen.
2. If the object is large enough to not burn up, it will certainly be slowed down. If it is slowed down enough to dip below terminal velocity, then it will naturally fall back to the Earth.
3. If it is moving fast enough, and is able to survive the transit through the atmosphere, it will naturally escape the Earth's atmosphere to just keep going.

Unfortunately, which possibility occurs will depend greatly on some calculations that I just don't know how to do offhand, so I couldn't even provide ballpark figures for where various objects would fall in these categories.

 

[hisgrace26]

Well, if you like, you can start reading up on eternal inflation here:
Inflation (cosmology) - Wikipedia, the free encyclopedia

So how does that theory account for space-time region? I might of have missed, but I don't read anything there that explains these new space. It woud help if you can break it down a little by little as simple as you can,. because I'm just a lay man. I want simplicity. Thanks.

 

[Chalnoth]

So how does that theory account for space-time region? I might of have missed, but I don't read anything there that explains these new space. It woud help if you can break it down a little by little as simple as you can,. because I'm just a lay man. I want simplicity. Thanks.

Well, maybe this will help you to visualize it.

In quantum mechanics, the vacuum isn't empty. It's continually sort of bending and flexing and jumping around, rather like the surface of boiling water. Every once in a while, one of these bends or flexes in the vacuum is big enough that it sort of pinches off. If the properties of this new region are just right, it can expand on its own, separate from its parent, producing an entirely new region of space-time.

 

[hisgrace26]

Well, maybe this will help you to visualize it.

In quantum mechanics, the vacuum isn't empty. It's continually sort of bending and flexing and jumping around, rather like the surface of boiling water. Every once in a while, one of these bends or flexes in the vacuum is big enough that it sort of pinches off. If the properties of this new region are just right, it can expand on its own, separate from its parent, producing an entirely new region of space-time.

Right, I see. So my question is: how can it create the new space-time area if there was no space? Wouldn't it required space for it to expand into or not? According to that theory it didn't need wouldn't it? Can you elaborate on this? Thanks.

 

[Chalnoth]

Right, I see. So my question is: how can it create the new space-time area if there was no space? Wouldn't it required space for it to expand into or not? According to that theory it didn't need wouldn't it? Can you elaborate on this? Thanks.

I don't see any reason to believe that there ever wasn't space-time of some sort.

However, that said, quantum mechanics may well be the answer here. Within quantum mechanics, if you have a region of space-time where there is the mere potential for a certain kind of particle to exist (e.g. an electron, or a proton, or whatever), then quantum mechanics guarantees that this kind of particle will be continuously popping in and out of the vacuum. Now, generally these fluctuations disappear almost instantly, but in certain specific situations they can continue indefinitely.

At present, we don't know much about quantum gravity, but if it works in a similar fashion, the mere potential for a space-time region to exist may force space-time regions to be generated in a very similar way. The difference here is that because new space-time regions don't require any energy at all, they can stay around indefinitely, unlike most quantum fluctuations with particles that don't.

 

[hisgrace26]

I don't see any reason to believe that there ever wasn't space-time of some sort.

It creates space as it expand. From what I'm getting it according to that theory.

 

[Tuddrussell]

When the Hulk lifts a heavy object the ground under him usually breaks from the strain.

That's simple and logical, but when Jean Grey lifts a comparable object it's as if all the weight just disappears, she can even lift an object while flying!

Where does that weight go?