The forum discussion centers on the discrepancy in the Hubble parameter values derived from different sources, specifically the Planck satellite data, which reports a value of 67.91 ± 0.89 kilometers per second per megaparsec, and supernova data, which suggests a value of 70.58 ± 0.83. This discrepancy raises questions about the implications for the age of the universe, commonly cited as 13.8 billion years. The discussion highlights the importance of understanding the energy content distribution of the universe and how it affects age calculations, emphasizing that the apparent tension between these measurements is not uncommon in cosmology.
PREREQUISITESAstronomers, cosmologists, and physics students interested in the latest discussions surrounding cosmic expansion and the implications of varying Hubble parameter measurements.
This is, at best, misleading. In a flat universe containing only a cosmological constant the Hubble constant is just that, a constant. In our actual universe, the Hubble rate is actually decreasing. As has already been stated in this thread, to find the age of the universe you need to solve the Friedmann equations backwards for the actual composition of the Universe.alantheastronomer said:If we use the present day value of the Hubble constant to calculate the age of the universe - the accelerated value - then we'll underestimate the age of the universe because the universe was expanding slower earlier on.
Again, as has already been stated, that the values are closer does not mean that the discrepancy is worse. You have to look at the error bars relative to the discrepancy.alantheastronomer said:The values you mention, 68 and 71, while not in agreement are much better than the way it used to be. Before, the discrepancy used to be between 50 and 100!
The Andromeda galaxy is within our local cluster, which is a gravitationally bound structure. It is not affected by the expansion.alantheastronomer said:the distance to our nearest neighbor - the Andromeda galaxy
I will buy that you did not explicitly say that Andromeda is affected by expansion, although it may be read that way. However, I can see no other interpretation of this:alantheastronomer said:I never said that the discrepancy was worse the closer the values were.
than you claiming that the discrepancy used to be worse because the values are further apart. There is absolutely no reference to error bars.alantheastronomer said:The values you mention, 68 and 71, while not in agreement are much better than the way it used to be. Before, the discrepancy used to be between 50 and 100!
On the 2 sources you named with their uncertainties, my answer is that one or both stated their uncertainties too small.windy miller said:You are ri
You are right I initially posted the wrong values I have now corrected this. But I don't see what the relevance is to the question. the question was do the different value of the Hubble parameter mean we should have two values for the time since the big bang? We've had more than a dozen posts in this thread now and no one has actually given a clear answer answer to the question in hand. Perhaps then you can see why someone gets frustrated by side shows like these. And i agree physics forums is excellent. But that doesn't mean there aren't cases of unnecessarily distracting the conversation or that things can't be improved. You didn't provide a reference that physics forums was 18 years old. since the numbers you initially stated were wrong! the forum was founded in 2001. here's a reference for you :
https://www.physicsforums.com/help/aboutu
Now the reference i have only gives us the year of founding: 2001 . it might have been dec 31 2001 for all i know in which case it is more like 16.2 years old. Which is further out on a percentage basis that I was on my values for the Hubble. Perhaps you can see how this sort of pedantry can get frustrating and waste people times?
Dont get me wrong I am all in favour of providing references. But there are cases when these are required and cases when they are not. to ask for the reference and pick apart your mistake about the age of physics forums is pedantry and I am doing it as a satirical way of making a point. . the truth in the point you make isn independent of wether the forums 18 years old, or whatever. So to focus on it is just silly. Same with my questions. To focus on the values of Hubble or even the sigma is to miss the point of the question. . of course we should correct false information but to do so without answering the questions in hand is just annoying. I think if someone asks a simple question on a forum about something that has been widely reported and not disputed then it would be simpler and easier to just answer the question. something I'm still waiting for.