Register | Sign In


Understanding through Discussion


EvC Forum active members: 57 (9173 total)
2 online now:
Newest Member: Neptune7
Post Volume: Total: 917,585 Year: 4,842/9,624 Month: 190/427 Week: 0/103 Day: 0/8 Hour: 0/0


Thread  Details

Email This Thread
Newer Topic | Older Topic
  
Author Topic:   How is the Universe here?
cavediver
Member (Idle past 3723 days)
Posts: 4129
From: UK
Joined: 06-16-2005


Message 85 of 131 (488263)
11-09-2008 10:19 AM
Reply to: Message 84 by Taz
11-09-2008 9:56 AM


Re: Back again, and let's first dispense with this nonsense...
I don't think the problem is people's outdated knowledge or belief.
In the case of the readers tyying to get their heads around the concept of fields, I would totally agree. What I'm referring to here is the attitude you see in the posts of e.g. john6zx and Buzsaw, and countless other web-based physics-cranks. It is not that they are having trouble with the concepts of fields - their understanding is still 100 years behind the point of even being able to approach fields. And of course, in the post I just made, we haven't even mentioned fields - although classical field theory lies behind the electromagnetism I discussed. As sson as someone starts arguing with - well, can I touch space? Can i touch time? So how can it be physical? - you know you have a struggle. Hence this post above - I'm going right back to basics to destroy this common perception of 'physical'. It's precisely this approach that recently helped Agobot go rather gaga in his nihilism phase And we'll soon get to the point where Holmes was once accusing me of trying to 'fuck with his mind'
I'd be surprised if you haven't pulled out your hair trying to explain something like the universal expansion of the universe to a lay person before.
Oh, only a few billion times In a one-on-one, it is much more simple as you can gauge their ability to understand, and present accordingly. The aim is simply for them to go away knowing more than they started (or at least have fewer misconceptions!) and for them to feel pleasure at having learned something complex about the Universe. It is not important for them to be able to pass an exam on it later. The problem is that this always leads to them passing it on to others, and very quickly the message becomes hopelessly corrupted in the inevitable Chinese Whispers. That is why there are so many horrible misconceptions floating around that actually started with professionals. I guess I should only present this stuff on the condition that the audience promises never to repeat it Anway, presenting at EvC is much more difficult because you have so little feel as to where to pitch the material.

This message is a reply to:
 Message 84 by Taz, posted 11-09-2008 9:56 AM Taz has not replied

Replies to this message:
 Message 87 by Stile, posted 11-10-2008 9:06 AM cavediver has replied
 Message 90 by GDR, posted 11-10-2008 2:00 PM cavediver has not replied
 Message 99 by AZPaul3, posted 11-21-2008 7:27 PM cavediver has not replied
 Message 127 by Lurkey, posted 11-08-2012 7:55 AM cavediver has replied

  
cavediver
Member (Idle past 3723 days)
Posts: 4129
From: UK
Joined: 06-16-2005


(1)
Message 94 of 131 (488505)
11-12-2008 9:04 AM
Reply to: Message 91 by Percy
11-11-2008 9:12 AM


Re: Back again, and let's first dispense with this nonsense...
My understanding of electrostatic forces... ...is that they're transmitted by exchanges of photons. Is that correct?
Yes, this is often how it is expressed, but they're actually virtual photons and also virtual electron/positron pairs as well. It's essentially a big messy interaction of the quantum fields.
If so, what is it about the exchange of photons that creates a force on the electrons
Uh-oh, I hate this question. Photons carry momentum, so you can easily imagine a photon causing a repulsion. Attraction is slightly harder to explain, but essentially, virtual photons can carry -ve momentum, which if you think about a transfer of -ve momentum from one electron to a second positron, actually causes attraction. Ah, but how does the photon know what particle is at the other end? If it's +ve, then it needs to transfer -ve momentum, and if it's -ve, it needs +ve momentum!! The photon carries no charge itself, so there is no way it can tell. Fortunately, it all comes out in the wash (well, the mathematics) but it is rather messy quantum mechanics, that needs a separate thread. The trick is to understand that whenever we say virtual particle (and I rarely do) what we mean is a complex interaction in the quantum fields that can have characteristics not found in those disturbances that give rise to 'real' particles.

This message is a reply to:
 Message 91 by Percy, posted 11-11-2008 9:12 AM Percy has not replied

  
cavediver
Member (Idle past 3723 days)
Posts: 4129
From: UK
Joined: 06-16-2005


Message 95 of 131 (488534)
11-12-2008 3:01 PM
Reply to: Message 87 by Stile
11-10-2008 9:06 AM


Re: No Questions... this time
Is there some actual minute possibiliy of something larger possibly passing through a brick wall?
It's staggeringly unlikely. To tunnel, your wavefunction must have an appreciable value in the region you want to tunnel into. But the wavefunctions of large objects are forced to have extremely small extent because of the practically inifnite interactions with the wavefunctions of the practically infininte number of other particles around us. This is decoherence. The only way to keep a wavefunction extended is to isolate it from interactions. This is possible for electrons, even atoms, and actually even molecules in the right extreme conditions. But at our size, it is simply not possible. This is probably no bad thing as our existence is very classical in nature!
But let's just say we could isolate you sufficiently in a chamber to have an extended wavefunction. You shouldn't feel any different, because you yourself would still be classical, as your own self-interactions are more than sufficient to create the decoherence. So your body and conciousness should be fine. But you can't see anything or experience anything as we have purposely isolated you from all external interactions. To us, you would be like Schrodinger's Cat - unobserved, and in a superposition of states that include you on one side of the chamber and you on the other side of the chamber. So it is possible that we could use this to teleport you through a wall that was also in the chamber. To be impressive, we'd need to make a really big isolation chamber. In which case, it would be the isolation chamber that would be the more impressive achievement
Edited by cavediver, : No reason given.

This message is a reply to:
 Message 87 by Stile, posted 11-10-2008 9:06 AM Stile has seen this message but not replied

Replies to this message:
 Message 96 by onifre, posted 11-12-2008 4:57 PM cavediver has not replied

  
cavediver
Member (Idle past 3723 days)
Posts: 4129
From: UK
Joined: 06-16-2005


Message 104 of 131 (491194)
12-12-2008 12:59 PM
Reply to: Message 103 by Agobot
12-12-2008 12:25 PM


Re: Back again, and let's first dispense with this nonsense...
What does it say?
It says nothing new - only that our calculations are getting better because we have better computers. I have said many times here at EvC that nearly all of the mass of a proton comes from 'binding energy' and not from the rest-mass of the basic quarks themselves. This binding energy arises from complex interactions of the quantum fields. They have managed to calculate these interactions better than before.

This message is a reply to:
 Message 103 by Agobot, posted 12-12-2008 12:25 PM Agobot has not replied

  
cavediver
Member (Idle past 3723 days)
Posts: 4129
From: UK
Joined: 06-16-2005


Message 110 of 131 (491217)
12-12-2008 3:13 PM
Reply to: Message 106 by Agobot
12-12-2008 2:14 PM


Re: Back again, and let's first dispense with this nonsense...
I'll leave it up to cavediver to say if the whole scientific community was aware that 99% of the mass of the nucleus came from virtual particles, or that it was his conviction/conclusion.
The whole scientific community? No. But professional particle and theoretical physicists? Yes, of course, and have done since we first forumulated QCD back in the early 1960s! (not that I was around then)

This message is a reply to:
 Message 106 by Agobot, posted 12-12-2008 2:14 PM Agobot has not replied

  
cavediver
Member (Idle past 3723 days)
Posts: 4129
From: UK
Joined: 06-16-2005


Message 121 of 131 (502640)
03-12-2009 4:00 PM
Reply to: Message 116 by Dr Jack
03-12-2009 10:49 AM


Re: 13.7 billion years ago? By who's reference?
you say time is relative, so there is no universal timeframe.
No, *I* don't say that It may be true in Special Relativity, but not always in General Relativity. The standard cosmological solutions admit a preferred rest-frame: the "comoving" rest-frame. You can say that it is the expansion of the Universe that provides the basis for this rest-frame. We clearly see it in the CMBR, and we have to subtract a doppler component from our observations of the CMBR based on our own peculiar motion wrt this rest-frame. Essentially, the 13.7 Ga age of the Universe is the *maximum* possible age of a test particle emitted at the Big Bang.

This message is a reply to:
 Message 116 by Dr Jack, posted 03-12-2009 10:49 AM Dr Jack has replied

Replies to this message:
 Message 122 by Dr Jack, posted 03-12-2009 4:01 PM cavediver has not replied

  
cavediver
Member (Idle past 3723 days)
Posts: 4129
From: UK
Joined: 06-16-2005


(5)
Message 128 of 131 (678499)
11-08-2012 5:13 PM
Reply to: Message 127 by Lurkey
11-08-2012 7:55 AM


Re: Back again, and let's first dispense with this nonsense...
Oh, I'm here And thanks - that means a great deal to me.
I'm always lurking but I have so little time these days to contribute much. When I joined EvC in 2005, I was working for myself, and a master of my own time. Now I'm a slave to running my company
I guess I should only present this stuff on the condition that the audience promises never to repeat it
Purely personal, but i have to disagree. There is something about this site that works and I reckon the passing on has a lot to do with it.
Yep, you're right. EvC is rather special, and some of the folks here have more than excelled themselves. That's one reason why I don't feel I'm letting the side down too much - for example, Catholic Scientist's cosmology explanations have become first rate.

This message is a reply to:
 Message 127 by Lurkey, posted 11-08-2012 7:55 AM Lurkey has not replied

Replies to this message:
 Message 129 by Stile, posted 11-09-2012 8:28 AM cavediver has not replied

  
Newer Topic | Older Topic
Jump to:


Copyright 2001-2023 by EvC Forum, All Rights Reserved

™ Version 4.2
Innovative software from Qwixotic © 2024