How Does the Balloon Analogy Explain the Expansion of the Universe?

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Discussion Overview

The discussion revolves around the balloon analogy as a means to explain the expansion of the universe and its relation to the concept of the Big Bang singularity. Participants explore the implications of this analogy in terms of dimensions, forces, and the nature of singularities, touching on theoretical aspects of cosmology and general relativity.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant describes the balloon analogy, explaining how the surface represents spacetime and the dots represent galaxies moving apart due to the expansion of the universe.
  • The same participant proposes a method to calculate the dimensions of the Big Bang singularity using the balloon analogy, introducing various physical parameters and equations related to tensile strength and pressure.
  • Another participant questions the validity of equating the Planck length with the size of the Big Bang singularity, suggesting that the concept does not make sense.
  • A different participant clarifies that a singularity is not a physical entity but a point where mathematical descriptions fail, emphasizing the breakdown of current physics at that point.
  • One participant describes the Big Bang singularity as a moment when all matter and energy were compressed into a point of zero volume, while also noting that during the Planck epoch, the laws of physics do not apply.
  • Another participant argues against calling the Planck size sphere a singularity, stating that it has a finite size, unlike the Big Bang singularity, which is defined as having zero size.

Areas of Agreement / Disagreement

Participants express differing views on the relationship between the Planck size and the Big Bang singularity, with some supporting the analogy and others challenging its validity. The discussion remains unresolved regarding the interpretation of singularities and the applicability of the balloon analogy in this context.

Contextual Notes

Participants highlight limitations in the balloon analogy, particularly its simplification of a three-dimensional universe into a two-dimensional surface and its inability to fully account for the complexities of cosmic expansion and singularities.

jv11
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TL;DR
Using balloon analogy of universe to calculate big bang singularity?
Here is quick explanation :

The Balloon as Space-Time:
The balloon's surface is analogous to a two-dimensional representation of our three-dimensional universe, where space and time are interwoven (spacetime).

Dots as Galaxies:
The dots on the balloon represent galaxies, which are not actually moving across the surface of the balloon, but rather being carried apart by the expansion of the balloon's surface itself.

Expansion of Space:
The inflation of the balloon signifies the expansion of the universe, where the fabric of space itself is stretching and causing galaxies to move away from each other.

No Center of Expansion:
A key point the balloon analogy illustrates is that there is no single "center" from which the universe is expanding. Just as every point on the balloon's surface sees other points moving away, every point in the universe sees all other points receding.

Limitations:
The balloon analogy is a simplification. Our universe is three-dimensional, and the analogy only represents it as a two-dimensional surface. Additionally, the balloon analogy doesn't account for the acceleration of the universe's expansion, which is a more complex aspect of the Big Bang.

I am aircraft maintenance engineer.

I have a question :

Can we try to calculate dimension of big bang singularity by using this balloon analogy?
Balloon (secured to ground) is inflated by pressure Po of air.
The pressure Po is acting on balloon wall and make the radius R bigger.

Any balloon has two radiuses:

1)
Rs-the smallest sphere - radius of balloon where pressure inside is zero
and elastic forces in the ballon wall
are smallest but still curve the ballon wall material in to the sphere.

2)
Rb- the biggest sphere- radius where pressure inside ballon is maximum.
The elastic forces are biggest.
If ballon is inflated beyond Rb radius- the wall of balloon ruptures.
The wall of balloon has a tensile strength(S).
The specifics tensile strength(Ss) is
Ss=S/D- density of balloon wall.
Ss is constant (depends only on temperature).
S=F/A
F- force acting on balloon wall
A- cross section area of material force acting on.(Radius of balloon).
The universe can be seen as a wall of balloon.
Gravity is the force pulling the balloon wall towards the center .
Dark mater and energy are pushing the wall of balloon outwards.
The wall itself is made of electromagnetic fields.The electromagnetic fields are either squished or pulled (they are material the balloon wall is made of).
The null energy condition, a concept in general relativity, places a theoretical limit on the specific strength of any field, including electromagnetic fields. This limit is approximately 9 x 10^13 kNm/kg.
Ss=9x10^10^16Nm/kg
This is Ss- specific tensile strength of
balloon wall.
Radius of balloon wall is size of visible universe:
Rb=4.4x10^26m
Ab=6*10^53
The current density of the universe is close to the06.8% Dar4.3% Da
critical density, which is estimated to be about 9 x 10^-27 kg/m'This density is a combination of ordinary mat-ter, dark matter, and dark energy.
D=9x10^-27kg
From formula
Ss=S/D
Tensile strength of ballon wall is:
S=Ss*D
S=9*10^16*9*10^-27
S=8.1*10^-10Pa
This is the pressure of forces acting on the in and out of balloon wall.
they are in balance .
From formula S=F/A
F=S*A
F=8.1*10^-10*10^53
F‎ = 8.1×10⁴³N
To calculate big bang balloon size or
radius Rs we have to go back to Planck epoch of big bang .
The Planck force Fp=1.21*10^44N is the force acting on the the “inside “Of the balloon.
The force F (of today)is very similar to Fp.
If force F is constant during inflation
From formula
S=F/A
Po=Sb=Planckpressure
Po=Sb=4.6x10^113Pa
From
intensity 1/intensity 2=d2^2/d1^2
We can see that tensile strength S of balloon wall follows the inverse square law with distance .
D=m/Vp
m=MASS OF UNIVERSE
m=10^54
D=10^54/4*10^-105
D=2.5*10^158kg/m3
Specific tensile strength for big bang is
Ssb =Sb/D
Ssb =4.6*10^113/2.5*10^158
Ssb=1.84*10^-45Nm/kg
The temperature during Planck epoch is:
tb=10^32 C
Ss specific tensile strength depends on temperature.
The temperature of universe is
t=-270 C
From :
tb/t=N1 and Ssb/Ss=N2
N1‎ = 10^32/-278‎ = -3.597×10²⁹
N2=9*10^16/1.84x10^-45=4.89*10^61
From N1 and N2 we can see that amount of Ss(specific tensile strength) drops with increase of temperature following inverse square law.


Could it be that Planck length is the size of big bang singularity?

Tx
 
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A singularity is not a physical thing. It's where the mathematics breaks down.
 
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Imagine taking all the matter and energy in the universe and squeezing it into a point of zero volume. That's essentially the idea of the Big Bang singularity. It's the moment when the universe as we know it began, but it's also a place where our current physics can't explain what happened.
This is big bang singularity in time t=0 sec.
In Planck epoch- t=10^-43sec- this is Planck size sphere - the laws of physics do not do not apply.
Could we call this big bang singularity?
The Planck size sphere fits perfect to be smallest size sphere with Rs of universe balloon analogy.
 
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jv11 said:
In Planck epoch- t=10^-43sec- this is Planck size sphere - the laws of physics do not do not apply.
Could we call this big bang singularity?
No, because a "Planck size sphere" by definition has a very small but finite size. The big bang singularity has zero size.
 
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