Ask a physicist anything.

[TerranceL]

It's mathematically heavy, and there's disagreement on just what a 'wavefunction' describes about a particle, but the basic idea is that an unmeasured particle has a wide range of possible states, and these states 'collapse' to just a few states when they are interfered with.

*blinks*

I actually understood that.


Wow.

 

[Doveaman]

I'm enjoying these physics-related threads so...

Ask a physicist anything .

I came across these two articles on another thread which suggests, IMO, that much of what is considered to be “missing mass” isn’t really “missing”, and much of what is considered to be “dark matter” isn’t really “dark”. Do you agree with this suggestion?

Astronomers find that Universe shines twice as bright

Galaxies Demand a Stellar Recount - NASA Jet Propulsion Laboratory

 

[Wiccan_Child]

I came across these two articles on another thread which suggests, IMO, that much of what is considered to be “missing mass” isn’t really “missing”, and much of what is considered to be “dark matter” isn’t really “dark”. Do you agree with this suggestion?

Astronomers find that Universe shines twice as bright

Galaxies Demand a Stellar Recount - NASA Jet Propulsion Laboratory

I've seen those articles before, and its hardly accounts for 'much' of dark matter. You've pushed the amount from 97% of the universe to 96%, if that.

You're grabbing at straws if you think this invalidates dark matter hypotheses. And besides, if you're going to rail against modern techniques (I think it was you who called them 'primitive', though I could be wrong), why not turn around and say that these new findings are also hopelessly wrong? Methinks the anti-dark-matter group are cherry-picking their findings.

 

[Doveaman]

I've seen those articles before, and its hardly accounts for 'much' of dark matter. You've pushed the amount from 97% of the universe to 96%, if that.

Maybe. But, what I find interesting is that you are seeing what cannot be seen and what can be seen you are not seeing. Makes one wonder how mush more you are not seeing that can be seen.

You're grabbing at straws if you think this invalidates dark matter hypotheses.

The was not my intent. See above.

And besides, if you're going to rail against modern techniques (I think it was you who called them 'primitive', though I could be wrong),

You are. Wasn't me. But that's OK.

why not turn around and say that these new findings are also hopelessly wrong? Methinks the anti-dark-matter group are cherry-picking their findings.

Maybe I'm "cherry-picking" my findings because the cherries are made of normal matter that can be found.

 

[Jazmyn]

Does sound travel faster through cold air?

 

[Wiccan_Child]

Does sound travel faster through cold air?

Yes, because the molecules are closer together. The sound is also clearer, because there is less thermal motion to muffle the sound (think of shouting in the wind: all that motion makes it hard to hear).

 

[Wiccan_Child]

Maybe. But, what I find interesting is that you are seeing what cannot be seen

That's the power of good evidence. I believe in atoms and cells and EM waves, though I can't see any of that.

and what can be seen you are not seeing.

Such as?

Maybe I'm "cherry-picking" my findings because the cherries are made of normal matter that can be found.

No, you're cherry-picking in that you have a double-standard when it comes to evaluating evidence and criticising techniques.

 

[TerranceL]

Yes, because the molecules are closer together. The sound is also clearer, because there is less thermal motion to muffle the sound (think of shouting in the wind: all that motion makes it hard to hear).

Is that why theaters are always so cold? Or is that merely for comfort?

 

[Wiccan_Child]

Is that why theaters are always so cold? Or is that merely for comfort?

I've never noticed that, to be honest. Maybe British theatres are heated differently. It could be that yours are made cooler to combat all that body heat, but when there's few people in there, it gets a bit nippy.

But I doubt it's to do with the acoustics. Cold air isn't that much better at transmitting sound.

 

[Jazmyn]

What's the best shape for a large room to be for the best acoustics?

 

[Jazmyn]

And what's the longest word in the english language without any vowels? Mwahahahahah!

 

[Doveaman]

Does anyone else ever wonder if the universe is just a huge brain?

I sometimes wonder if the universe isn’t just one huge brain. I mean, the electric discharges in space are somewhat similar to the electric discharges in the human brain. So maybe the universe is just one huge ever expanding brain.

 

[Wiccan_Child]

What's the best shape for a large room to be for the best acoustics?

And what's the longest word in the english language without any vowels? Mwahahahahah!

I can think of 'spryly', provided a 'vowel' is either a, e, i, o, or u. If you want a word without vowel sounds, then 'church' comes to mind, if have my accent (I come from Somerset, so I have a rather rhotic pronunciation).

Wikipedia informs me that 'myrrh' could be considered as well.

 

[TerranceL]

I've never noticed that, to be honest. Maybe British theatres are heated differently. It could be that yours are made cooler to combat all that body heat, but when there's few people in there, it gets a bit nippy.

But I doubt it's to do with the acoustics. Cold air isn't that much better at transmitting sound.

OK that does make sense... I tend to go to the movies when there is a good chance to be the least amount of people. (I'm not anti-social that just lessens the chance you are going to have people bringing their infants to the theater.) Now that I think about it, when I'm in a theater that's filled it's not nearly as cold as it is when it's just me and the other shutins. Which makes sense.

Ok, thanks!

 

[Michael]

Seven questions that keep physicists up at night - space - 23 October 2009 - New Scientist

There are the 7 questions that supposedly keep you guys/gals up at night. Enjoy.

 

[Jazmyn]

If you made the panama canal really big and deep, would it affect sea currents?

 

[Doveaman]

Seven questions that keep physicists up at night - space - 23 October 2009 - New Scientist

There are the 7 questions that supposedly keep you guys/gals up at night. Enjoy.

4% normal matter, 25% dark matter (based on assumptions), and the rest as dark energy (also based on assumptions) doesn’t say much for the mainstream model of the universe, which they themselves readily admit is far from adequate.

What I find interesting is that they admit there is something theoretically wrong but then try to make being wrong seem like a good thing scientifically.

Katherine Freese’s suggestion that maybe a new theory is needed is not a bad idea IMO.

 

[catzrfluffy]

How is the half-life of an atom determined?

 

[Wiccan_Child]

If you made the panama canal really big and deep, would it affect sea currents?

It's very likely, given how currents flow around the American continent would be completely altered. I daresay the Suez and Panama canals have likely done that already, to an extent.

How is the half-life of an atom determined?

Experimentally. According to my calculations, if you know how much of an atom you have at two different times (N[sub]1[/sub] at time t[sub]1[/sub], and N[sub]2[/sub] at time t[sub]2[/sub]), then the half-life of that atom is given by:

t[sub]1/2[/sub] = -ln(2)(t[sub]1[/sub]-t[sub]2[/sub]) / (ln(N[sub]1[/sub])-ln(N[sub]2[/sub]))

So by measuring these two quantities, you can get the half-life. Even if it's a million years, you can work it out by measuring it at, say, Jan 2008 and Jan 2009.

 

[Wiccan_Child]

Seven questions that keep physicists up at night - space - 23 October 2009 - New Scientist

There are the 7 questions that supposedly keep you guys/gals up at night. Enjoy.

Ah, the hard questions .

4% normal matter, 25% dark matter (based on evidence and observation), and the rest as dark energy (also based on evidence and observation)

Fixed.

doesn’t say much for the mainstream model of the universe, which they themselves readily admit is far from adequate.

Incomplete? Sure. But inadequate? Please.

What I find interesting is that they admit there is something theoretically wrong but then try to make being wrong seem like a good thing scientifically.

Which betrays your utter lack of understanding of how science works.