Is there a contradiction here.

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Discussion Overview

The discussion revolves around perceived contradictions in cosmological concepts, specifically regarding the age of the universe, proton decay, and the expansion of space. Participants explore theoretical implications of these ideas, including the nature of the observable universe and the behavior of light and matter over cosmic distances.

Discussion Character

  • Debate/contested
  • Conceptual clarification
  • Exploratory

Main Points Raised

  • Some participants suggest that the half-life of protons being greater than the age of the universe raises questions about the implications of proton decay, which is considered speculative and unobserved.
  • There is a discussion about the observable universe's radius and how it relates to the age of the universe, with some arguing that objects at the boundary appear to have traveled faster than light due to the expansion of space.
  • One participant posits that if the universe began as a singularity, then matter at the edge must have expanded faster than light to reach its current distance from the center.
  • Another participant clarifies that while light from distant objects takes time to reach us, the expansion of space allows for distances to increase at rates exceeding the speed of light, in accordance with Hubble's law.
  • There is a contention regarding the concept of a center of expansion, with some emphasizing that there is no central point in the universe from which expansion occurs.
  • Some participants express uncertainty about the implications of spacetime distortion and whether it allows for faster-than-light travel, with differing views on the nature of space expansion.

Areas of Agreement / Disagreement

Participants express multiple competing views regarding the implications of the universe's expansion and the nature of light and matter. The discussion remains unresolved, with no consensus on the interpretations of these cosmological concepts.

Contextual Notes

Participants note that the concepts discussed involve significant uncertainties and depend on interpretations of cosmological models, including the nature of spacetime and the expansion of the universe. The implications of proton decay and the observable universe's characteristics are also highlighted as areas of ongoing debate.

dpa
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list of contradictory situations.
1. Age of universe is determined by rate of proton decays at some place taking into consideration half life of proton.
But since ALL protons were created after big bang, how can protons even decay. Considering the fact that their half life is greater than present life of universe.

2. Everyone knows that radius of universe in terms of speed of light (more than 13billion yrs) meanins that it takes light more than 13 billion years to reach curcumference from centre. is definite larger than age of universe. It implies that objects/stars at boundary traveled faster than light. Is not here too another contradiction.

Any ideas.
 
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1. the half-life of the proton is the amount of time it takes for the number of protons in the Universe to reduce by half. A half-life greater than the best-estimate age of the Universe just means that more than half of the protons the Universe started out with are still around.

Note:
proton decay is highly speculative and has not been observed - therefore has not formed part of our knowledge of the age of the Universe.
See age of universe for three common methods. These are discussed, and the uncertainties of each accounted for in a final estimate.

2. That is the radius of the observable Universe - it is how far we can see from here.
The rest of the statement is not clear -
The age of the universe is about 13.75 billion years, but due to the expansion of space we are observing objects that were originally much closer but are now considerably farther away (as defined in terms of cosmological proper distance, which is equal to the comoving distance at the present time) than a static 13.75 billion light-years distance.[2] The diameter of the observable universe is estimated to be about 28 billion parsecs (93 billion light-years),[3] putting the edge of the observable universe at about 46–47 billion light-years away.[4][5]
... what was your question? What is bigger than who?
 
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sorry for unclear language.
2.
A. Universe started as singularity or near singularity.
B. Matter at the edge of universe traveled from O or approx. O radius to present 46 billion light years radius in 13 billion years.
C. Light takes 46 billion years to cover same distance.
D. Does this mean matter had to travel/expand faster than light to reach to the present horizon of universe from r=0 position.
 
Gotcha - 14bil years ago some light got send towards us from point P, 14bil ly away.
14bil years later, point P is 46bil ly away and we get the light.
this gives an average speed of 46-14/14=2.3c

But this is faster than the speed of light! :)

from wikipedia.
due to Hubble's law regions sufficiently distant from us are expanding away from us much faster than the speed of light (special relativity prevents nearby objects in the same local region from moving faster than the speed of light with respect to each other, but there is no such constraint for distant objects when the space between them is expanding; see uses of the proper distance for a discussion)

There are a few things that can go FTL without violating relativity.
Space-Time is one of them. Well spotted.

Note:
your point B seems to suggest expansion from a center - there is no center to expand from.
 
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As Simon points out, relativity forbids objects locally from moving at > c wrt each other. It does not forbid the expansion of space between distant objects causing them to recede at speeds > c.
 
dpa said:
It implies that objects/stars at boundary traveled faster than light. Is not here too another contradiction.
In addition to the comments above, I would like to point out that in modern cosmology there is no boundary/edge to the universe.
 
@dalespam. sorry for that error

can i deduce then that the spacetime continuum even long after big bang/perhaps even today is/was highly distorted to allow matter to travel faster than light and hence expansion of universe is far complicated than expanding balloon.

Excuse me if i appear idiotic here.
 
Does this mean matter had to travel/expand faster than light

no...space expanded FTL.

...the spacetime continuum even long after big bang/perhaps even today is/was highly distorted to allow matter to travel faster than light,,,,

also no, it's the [new expansion] space between that is causing the apparent speed...

Spacetime in the observable universe is generally pretty flat and uniform...not within solar systems and galaxies and their attendent dark matter and dark energy necessarily, but at intergalactic distances.
 
Here's an online article about Cosmology from Scientific American that is good:

http://space.mit.edu/~kcooksey/teaching/AY5/MisconceptionsabouttheBigBang_ScientificAmerican.pdf
 
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