Menu
News
All News
Dungeons & Dragons
Level Up: Advanced 5th Edition
Pathfinder
Starfinder
Warhammer
2d20 System
Year Zero Engine
Industry News
Reviews
Dragon Reflections
Columns
Weekly Digests
Weekly News Digest
Freebies, Sales & Bundles
RPG Print News
RPG Crowdfunding News
Game Content
ENterplanetary DimENsions
Mythological Figures
Opinion
Worlds of Design
Peregrine's Next
RPG Evolution
Other Columns
From the Freelancing Frontline
Monster ENcyclopedia
WotC/TSR Alumni Look Back
4 Hours w/RSD (Ryan Dancey)
The Road to 3E (Jonathan Tweet)
Greenwood's Realms (Ed Greenwood)
Drawmij's TSR (Jim Ward)
Community
Forums & Topics
Forum List
Latest Posts
Forum list
*Dungeons & Dragons
Level Up: Advanced 5th Edition
D&D Older Editions
*TTRPGs General
*Pathfinder & Starfinder
EN Publishing
*Geek Talk & Media
Search forums
Chat/Discord
Resources
Wiki
Pages
Latest activity
Media
New media
New comments
Search media
Downloads
Latest reviews
Search resources
EN Publishing
Store
EN5ider
Adventures in ZEITGEIST
Awfully Cheerful Engine
What's OLD is NEW
Judge Dredd & The Worlds Of 2000AD
War of the Burning Sky
Level Up: Advanced 5E
Events & Releases
Upcoming Events
Private Events
Featured Events
Socials!
Twitch
YouTube
Facebook (EN Publishing)
Facebook (EN World)
Twitter
Instagram
TikTok
Podcast
Features
Top 5 RPGs Compiled Charts 2004-Present
Adventure Game Industry Market Research Summary (RPGs) V1.0
Ryan Dancey: Acquiring TSR
Q&A With Gary Gygax
D&D Rules FAQs
TSR, WotC, & Paizo: A Comparative History
D&D Pronunciation Guide
Million Dollar TTRPG Kickstarters
Tabletop RPG Podcast Hall of Fame
Eric Noah's Unofficial D&D 3rd Edition News
D&D in the Mainstream
D&D & RPG History
About Morrus
Log in
Register
What's new
Search
Search
Search titles only
By:
Forums & Topics
Forum List
Latest Posts
Forum list
*Dungeons & Dragons
Level Up: Advanced 5th Edition
D&D Older Editions
*TTRPGs General
*Pathfinder & Starfinder
EN Publishing
*Geek Talk & Media
Search forums
Chat/Discord
Menu
Log in
Register
Install the app
Install
The
VOIDRUNNER'S CODEX
is coming! Explore new worlds, fight oppressive empires, fend off fearsome aliens, and wield deadly psionics with this comprehensive boxed set expansion for 5E and A5E!
Community
General Tabletop Discussion
*Geek Talk & Media
"Speed of Light"
JavaScript is disabled. For a better experience, please enable JavaScript in your browser before proceeding.
You are using an out of date browser. It may not display this or other websites correctly.
You should upgrade or use an
alternative browser
.
Reply to thread
Message
<blockquote data-quote="tomBitonti" data-source="post: 6279354" data-attributes="member: 13107"><p>The rate of expansion (often, the <em>Hubble Parameter</em>) is only recently known to any decent accuracy. (To about 2% is what I'm seeing, say, around 71-73. Previously, values between 50-80 seemed usual.)</p><p></p><p>This seems to make the basic case for acceleration:</p><p></p><p><a href="http://www.ncbi.nlm.nih.gov/pmc/articles/PMC314128/figure/fig6/" target="_blank">http://www.ncbi.nlm.nih.gov/pmc/articles/PMC314128/figure/fig6/</a></p><p></p><p>That seems to show acceleration starting some time in the past, and increasing since then.</p><p></p><p>Given the uncertainties in the measurements, telling the rate of acceleration seems unlikely.</p><p></p><p>The basic implication is that a computation of the age of the universe cannot rely on a constant Hubble parameter values.</p><p></p><p>One measure of the age of the universe is telling the amount the background radiation is red-shifted: That shift basically integrates the effect of expansion over time. Then, knowing the rate of expansion, and inverting the integration, the age can be obtained.</p><p></p><p>An increasing Hubble parameter will make for the same shift over a smaller amount of time. Not sure quantitatively how much that would be, but I'm guessing on the order of 10%, or a small multiple thereof, for the measured acceleration, and not of the order of 100% or more. But, I could be very off on that estimate, and the estimate is very probably thrown off anyways by the basic uncertainty of the current parameter value.</p><p></p><p>Just to say, I find just a bit disturbing the image of an increasingly sparse universe, with its parts flying apart close to the speed of light, as an end-state of the universe. Hopping 100 trillion years forward would leave you in a very empty universe.</p><p></p><p>---</p><p></p><p>So many interesting links found while looking up various questions in this space:</p><p></p><p><a href="http://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=2&ved=0CDQQFjAB&url=http%3A%2F%2Fwww.astro.caltech.edu%2F~george%2Fay127%2Freadings%2FFreedmanMadore2010.pdf&ei=IEQrU666G-PD0QGQmoHIDA&usg=AFQjCNFVrdFROuRMqdy03RWYtg0GHSq8Zw&bvm=bv.62922401,d.dmQ&cad=rja" target="_blank">http://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=2&ved=0CDQQFjAB&url=http://www.astro.caltech.edu/~george/ay127/readings/FreedmanMadore2010.pdf&ei=IEQrU666G-PD0QGQmoHIDA&usg=AFQjCNFVrdFROuRMqdy03RWYtg0GHSq8Zw&bvm=bv.62922401,d.dmQ&cad=rja</a></p><p></p><p>This one is amusing:</p><p></p><p><a href="http://www.answersingenesis.org/articles/tj/v9/n1/hubble" target="_blank">http://www.answersingenesis.org/articles/tj/v9/n1/hubble</a></p><p></p><p>Thx!</p><p></p><p>TomB</p></blockquote><p></p>
[QUOTE="tomBitonti, post: 6279354, member: 13107"] The rate of expansion (often, the [i]Hubble Parameter[/i]) is only recently known to any decent accuracy. (To about 2% is what I'm seeing, say, around 71-73. Previously, values between 50-80 seemed usual.) This seems to make the basic case for acceleration: [url]http://www.ncbi.nlm.nih.gov/pmc/articles/PMC314128/figure/fig6/[/url] That seems to show acceleration starting some time in the past, and increasing since then. Given the uncertainties in the measurements, telling the rate of acceleration seems unlikely. The basic implication is that a computation of the age of the universe cannot rely on a constant Hubble parameter values. One measure of the age of the universe is telling the amount the background radiation is red-shifted: That shift basically integrates the effect of expansion over time. Then, knowing the rate of expansion, and inverting the integration, the age can be obtained. An increasing Hubble parameter will make for the same shift over a smaller amount of time. Not sure quantitatively how much that would be, but I'm guessing on the order of 10%, or a small multiple thereof, for the measured acceleration, and not of the order of 100% or more. But, I could be very off on that estimate, and the estimate is very probably thrown off anyways by the basic uncertainty of the current parameter value. Just to say, I find just a bit disturbing the image of an increasingly sparse universe, with its parts flying apart close to the speed of light, as an end-state of the universe. Hopping 100 trillion years forward would leave you in a very empty universe. --- So many interesting links found while looking up various questions in this space: [url]http://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=2&ved=0CDQQFjAB&url=http%3A%2F%2Fwww.astro.caltech.edu%2F~george%2Fay127%2Freadings%2FFreedmanMadore2010.pdf&ei=IEQrU666G-PD0QGQmoHIDA&usg=AFQjCNFVrdFROuRMqdy03RWYtg0GHSq8Zw&bvm=bv.62922401,d.dmQ&cad=rja[/url] This one is amusing: [url]http://www.answersingenesis.org/articles/tj/v9/n1/hubble[/url] Thx! TomB [/QUOTE]
Insert quotes…
Verification
Post reply
Community
General Tabletop Discussion
*Geek Talk & Media
"Speed of Light"
Top