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Author Topic:   Time and Beginning to Exist
Son Goku
Inactive Member


Message 158 of 302 (642616)
11-30-2011 8:30 AM
Reply to: Message 148 by kbertsche
11-29-2011 8:55 PM


The universe did not begin to exist 13.7 billion years ago.
So you would actually deny that the universe began to exist about 13.7 billion years ago?!? If you don't like "begin to exist", how would you prefer to describe the finite age of the universe and its origin in a singularity? Any comments from Cavediver or others actually trained in cosmology?
The standard Big Bang model of Cosmology (Lambda-CDM model) combined with experimental data tells us that the universe was very small 13.7 billion years ago, not that it began at that point.
The initial singularity is a mathematical artefact produced when you extrapolate General Relativity beyond the limits of its applicability, it's not the origin of the universe.

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 Message 148 by kbertsche, posted 11-29-2011 8:55 PM kbertsche has seen this message but not replied

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 Message 163 by designtheorist, posted 11-30-2011 10:15 AM Son Goku has replied

  
Son Goku
Inactive Member


(2)
Message 170 of 302 (642643)
11-30-2011 11:33 AM
Reply to: Message 163 by designtheorist
11-30-2011 10:15 AM


Re: Reply to Son Goku
Briefly, it is impossible for an infinitely hot and infinitely dense singularity to remain in that condition for any period of time without immediately expanding rapidly.
Allow me to explain again. The standard Big Bang model does not contain a singularity. The Big Bang model will develop a mathematical artefact, known as a singularity, if you push it beyond its current limits. We know however that the model cannot be pushed back this far, since several approximations it makes are no longer valid.
So the standard Big Bang model only says that 13.7 billion years the universe was microscopically small and it has been expanding since then. It does not discuss the beginning of the universe. For all we know the universe is 100 trillion years old, infinitely old, e.t.c. We don't know. However, we do know that it was microscopically small 13.7 billion years ago (but not an infinitely small singularity) and that the vast majority of its present day features can be explained from this fact.

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 Message 163 by designtheorist, posted 11-30-2011 10:15 AM designtheorist has not replied

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 Message 172 by cavediver, posted 11-30-2011 11:35 AM Son Goku has replied

  
Son Goku
Inactive Member


(1)
Message 174 of 302 (642647)
11-30-2011 11:39 AM
Reply to: Message 172 by cavediver
11-30-2011 11:35 AM


Re: Reply to Son Goku
Woops! Bit of clarification needed there.
I should have said the observable part of the universe (i.e. what we can see today) was microscopically small. The whole universe is a different story, we don't even know how big it is now.

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 Message 172 by cavediver, posted 11-30-2011 11:35 AM cavediver has not replied

  
Son Goku
Inactive Member


(1)
Message 178 of 302 (642653)
11-30-2011 11:55 AM
Reply to: Message 176 by designtheorist
11-30-2011 11:48 AM


Re: Reply to Cavediver
The energy scale at which electromagnetism disappears is known as the electroweak unification scale. Its value is 200 GeV which is about 2,400,000,000,000,000 Kelvin in terms of temperature. (2.4 PetaKelvins)
The early universe's energy reached well beyond this. Light and electromagnetism came into existence about 0.000000000001 seconds after the earliest point described by the Big Bang model.

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 Message 176 by designtheorist, posted 11-30-2011 11:48 AM designtheorist has not replied

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 Message 189 by Son Goku, posted 12-01-2011 9:34 AM Son Goku has not replied

  
Son Goku
Inactive Member


(1)
Message 189 of 302 (642752)
12-01-2011 9:34 AM
Reply to: Message 178 by Son Goku
11-30-2011 11:55 AM


Appearance of Electromagnetism
I've been thinking my previous post was a little vague. One might wonder how exactly electromagnetism can just appear or disappear, since it's an entire force.
In quantum field theory we usually say that particles are small lumps in the fields and in this way the fields come first or are more fundamental than the particles. However there are actually special conditions on when exactly the lumps of a field will correspond to what we perceive as a particle. One of these conditions is that the field should have a value of 0 when the energy is 0. Or to put it another way, if there is no energy the field should be completely still at its lowest value (which is 0) everywhere.
If this doesn't happen, for example if at zero energy the field is still of strength 6 (let's say) at every point, then you can't associate its lumps with particles. The lumps are still there, but they don't manifest as particles.
So in the early universe we had the electroweak field, with its four particles, the three weak isospin bosons and the Hypercharge boson, along with the doublet field, which also has four particles associated with it. Physics at this time would have looked extremely different.
However eventually the doublet field acquired a value everywhere in space, even when it had zero energy. This basically meant that the lumps which used to manifest as particles, no longer appeared as particles. Instead different lumps of the electroweak field and the doublet field manifested as particles. These being the two W bosons, the Z boson (both responsible for radioactive decay), the photon, which is the particle of electromagnetism and light and the Higgs particle, which is the only part of the doublet field possibly still visible*. So these new particles would have come into existence after the doublet field settle into its particular value** everywhere.
*We know the above picture is true, the only doubt is the exact way it works out. I've given the standard picture here, where the doublet field is the one that settled into a particular value. However it's possible it was some other field instead. The reason we need to find the Higgs is to confirm it was the doublet field. If we don't find the Higgs, it means it was another field. However the basic model of some field settling into a value and shifting what field lumps were particles is correct. This is why if the Higgs isn't found it isn't "The End of Physics" as some news articles make out to be the case. It just means it wasn't the simplest guess of a doublet field, but some other field.
**The value is 200 GeV everywhere, or roughly a thousand times less energy than a mosquito spends when it flies for one second.
Edited by Son Goku, : Better Title
Edited by Son Goku, : To stress a point.

This message is a reply to:
 Message 178 by Son Goku, posted 11-30-2011 11:55 AM Son Goku has not replied

Replies to this message:
 Message 191 by Percy, posted 12-01-2011 10:05 AM Son Goku has replied

  
Son Goku
Inactive Member


(1)
Message 192 of 302 (642760)
12-01-2011 10:43 AM
Reply to: Message 191 by Percy
12-01-2011 10:05 AM


Re: Appearance of Electromagnetism
I don't usually try to understand this stuff, but your explanation was so simple and clear I feel like I almost have a chance.
Brilliant!
So the field is a tuple of (strength, energy) at every point in space? If so, what's the strength correspond to?
It's basically how much of the field is present at the point. If you had some measuring device that measured how much field there was, like a Tesla meter for a magnetic field, it's the value that would appear on the meter. An example of such a quantity is voltage for a current, it's the "strength" of the field, but that's not exactly the same thing as the energy, since voltage is measured in volts, but energy in Joules.
And if a "lump" has a non-zero strength but a zero energy, which doesn't manifest as a particle, then what does it manifest as? In other words, if when we observe one of these types of lumps, what is it that we observe?
Basically, we actually can't observe them directly anymore. Think of the electroweak field like an ocean of four different types of liquid:
A,B,C,D.
A,B,C are the weak isospin fields and D the Hypercharge field.
There was also the doublet field, also an ocean of four liquids E,F,G,H.
Originally each of those liquids could come in discrete lumps, that we call particles. Think of particles as small parcels of these liquids (this isn't silly analogy by the way, thats pretty much what particles are.)
However this was only possible when the doublet field had zero strength at zero energy. Once the doublet field was no longer like this, it basically became impossible to parcel the liquids in the way they originally were. So, instead of the possible parcels being:
1. A
2. B
3. C
4. D
5. E
6. F
7. G
8. H
After the doublet field took its value, it would take an infinite amount of energy to make a parcel/particle of just A. So instead the parceling changed to a different system that took a finite amount of energy.
This system was:
1. A + B + E, the W+ boson
2. A + B + F, the W- boson
3. C + D + G, the Z boson
4. C + D, the photon
5. H, the Higgs boson
Which is the way it still is today. This shift in possible packagings is known as Spontaneous Symmetry breaking.
Please let me know if this is in anyway unclear.

This message is a reply to:
 Message 191 by Percy, posted 12-01-2011 10:05 AM Percy has replied

Replies to this message:
 Message 234 by Percy, posted 12-13-2011 7:49 AM Son Goku has replied

  
Son Goku
Inactive Member


(3)
Message 235 of 302 (643940)
12-13-2011 9:40 AM
Reply to: Message 234 by Percy
12-13-2011 7:49 AM


Re: Appearance of Electromagnetism
Don't these oceans occupy the same space?
Yes, they do indeed.
If so, what makes them two different oceans and why aren't they considered one ocean of 8 liquids?
Good point. Something I left out of my previous explanation. Basically the electroweak field is a vector field and the doublet field is a scalar field.
An example of a vector field is the wind velocity on the Earth's surface, which requires an vector at each point to describe the wind speed and direction. Similarly the electroweak field has a magnitude and direction at each point, which in some sense would tell you how much it effects the velocities of fields that interact with it. The doublet field on the other hand is just a number at each point, like temperture on the Earth's surface. From the point of view of the oceans of liquids, this doesn't matter, but it's the basic reason they can't be put together.
What does "After the doublet field took its value" mean,
When the universe cooled enough, the doublet field assumed a certain strength value, even though it had zero energy. It basically got "locked" into a particular value everywhere, similar to how crystals get locked into a particular shape after you cool them from molten crystal. (In fact the same mathematics describes both)
and why would the fact that it has taken its value cause it to require an infinite amount of energy to make a parcel/particle of just one liquid?
Basically when we want to reshape a crystal, we have to melt it and then cool it again to get another shape. Different crystal shapes will then reflect light differently. Similarly different "locked" values of the doublet field will give different packagings of "field liquid", the only way to change this or to return to the original packaging is to reheat the whole universe, since the doublet field is everywhere. Reheating the whole universe would take infinite/effectively infinite energy.
So, before the doublet field took its value, in addition to the single-parcel possibilities, weren't combinations of parcels possible?
In the way I've given it, no.
If not, why not?
The value of the doublet field is one of the physical quantities that effects what packagings are possible or not. Just as the shape of a crystal determines the strength of light and colour spectrum of the light reflected by it.
More directly however for each different combination of colours we can make a "subfield" of those colours, for example I could have a "C + D + G" field, from my previous post. These subfields can only be packaged into particles if they have zero strength at zero energy. The reason being that if a field has some strength at zero energy it has none of the correct properties (doesn't evolve correctly) to make particles.
However since all these fields interact with the doublet field, some of their field strength comes from it. If its value is just right, it will cancel against the other things contributing to the fields strength and the "C + D + G" field will have zero-strength and so it can create particles.
Why do you mention particles at one point, but your list of combinations after the doublet field took its value only includes bosons?
I include only the bosons for simplicity. If I used the fermions, things get a little more complicated. For example the colours mix differently for a left spinning electron and a right spinning electron, which would make the presentation a bit more difficult. However the basic mechanism is the same, I just excluded them for technical complexity and length (there's a lot of fermions).
Does the name "Spontaneous Symmetry Breaking" imply that the doublet field took its value spontaneously?
Actually no. The name is historical in origin. Originally the idea was used for crystals and ferromagnets, which do seem to spontaneously pick a shape or direction at random. Since the mathematics is the same we just use the same name. However the doublet field would have settled into its value. Although I guess when the settling occurs over a fraction of a second you could call it spontaneous.

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 Message 234 by Percy, posted 12-13-2011 7:49 AM Percy has not replied

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 Message 236 by New Cat's Eye, posted 12-13-2011 10:39 AM Son Goku has not replied

  
Son Goku
Inactive Member


Message 280 of 302 (881851)
09-02-2020 8:22 AM


Deep down
It's very hard what to make of these things.
Ultimately one would like to say something like:
Large object -> High level material description -> Chemistry -> Atomic Physics
in some sense.
The problem is ultimately you reach atomic level phenomena and things at that level are only described in terms of their effects on larger things not in terms of what they are in themselves. And thus one's fundamental physical theory requires the "Large Objects" at the start of the chain to even get off the ground. Also the theory has to assume some form of "observer" that "chooses" what phenomena to evoke from the microscopic scale.
This is just one of the many ways in which QM violates reductionism. Technically for example the colours I see aren't supervenient on the electromagnetic spectrum. I don't really think there is a philosophy that captures the current picture of the world from physics except to learn Quantum Theory in detail.

Replies to this message:
 Message 281 by vimesey, posted 09-02-2020 8:46 AM Son Goku has replied

  
Son Goku
Inactive Member


Message 282 of 302 (881853)
09-02-2020 9:00 AM
Reply to: Message 281 by vimesey
09-02-2020 8:46 AM


Re: Deep down
Yeah that's right.
Just with the caveat that it only works with classical relativity, i.e. you don't start talking about quantum matter. But that's a whole other kettle of fish.

This message is a reply to:
 Message 281 by vimesey, posted 09-02-2020 8:46 AM vimesey has replied

Replies to this message:
 Message 283 by vimesey, posted 09-02-2020 9:21 AM Son Goku has replied

  
Son Goku
Inactive Member


Message 284 of 302 (881855)
09-02-2020 9:33 AM
Reply to: Message 283 by vimesey
09-02-2020 9:21 AM


Re: Deep down
The first 50 pages of Ray d'Inverno's "Introducing Einstein's Relativity" are generally considered a nice intro to Special Relativity.

This message is a reply to:
 Message 283 by vimesey, posted 09-02-2020 9:21 AM vimesey has replied

Replies to this message:
 Message 285 by vimesey, posted 09-02-2020 9:42 AM Son Goku has not replied

  
Son Goku
Inactive Member


Message 287 of 302 (881861)
09-02-2020 12:52 PM


She's really good at explaining stuff in quantum theory as well. I'd check out her measurement problem video.

Replies to this message:
 Message 288 by Phat, posted 09-20-2020 9:17 AM Son Goku has replied

  
Son Goku
Inactive Member


(2)
Message 289 of 302 (882389)
09-20-2020 9:46 AM
Reply to: Message 288 by Phat
09-20-2020 9:17 AM


Re: Speculation within the limits of a science mind
Difficult questions! I don't think I'll provide very satisfactory answers. I'll stay with the quantum physics side.
As for the sociological question of whether religion will last. I simply don't know. In response to quantum theory Bohr remained a committed atheist, Heisenberg became more deeply Catholic, Pauli delved into Jungian idealism and metaphysics and Schrodinger started to believe in Vedic philosophical views.
So I don't really know if physics say will definitely lead people away from religious views.
I think it's fairly clear from quantum theory that there's something beyond the scientific/physical, and you'll see this discussed fairly soberly in works by Bernard d'Espagnat or Jeffrey Bub for example. Bub has a nice phrase that quantum theory is clearly "non-representational", i.e. it doesn't discuss what the world is actually like. To paraphrase Bohr it's about what you can "say and do" not about what "is".
However it seems, as pointed out by Oppenheimer a few times, that quantum theory simply tells you what the metaphysics is not with little guidance as to what it is. So hard to know where to go from there. d'Espagnat's books sketch out a few options, but once you accept that you have no solid grasp on metahpysics accepting any of them is just belief as such.
Some say (e.g. Jeffrey Bub) that a far reaching agnosticism is called for. I don't just mean about God vs no God, but about metaphysics in general. Hard to know.

This message is a reply to:
 Message 288 by Phat, posted 09-20-2020 9:17 AM Phat has seen this message but not replied

  
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