# What happens if c decreases? **URL:** \ **Category:** Factual Questions\ **Created:** [September 10, 2011, 4:04pm UTC](https://boards.straightdope.com/t/what-happens-if-c-decreases/595832 "2011-09-10T16:04:09Z")\ **Posts on this page:** 4\ **Page:** 2
**Author:** ![Frylock](https://avatars.discourse-cdn.com/v4/letter/f/ce7236/32.png) [@Frylock](https://boards.straightdope.com/u/Frylock)\ **Post date:** [September 12, 2011, 10:37am UTC](https://boards.straightdope.com/t/what-happens-if-c-decreases/595832/21 "2011-09-12T10:37:49Z")
> [@Triskadecamus](#): > > No, it means our system defines c as = 1, and if you change it, the value of 1 is changed. Or c, but you can’t tell the difference. Fair enough==“c=x” for any x, you’re saying, is exactly as meaningful, no more no less, than “1=1.” But 1=1 is a tautology, which, while not meaningless, is uninformative. But c=x (for any x other than c) is informative. It seems like you’re saying “The evening star is the morning star” is exactly as meaningful as “venus is venus”. But of course this would be false. On the other hand, asking “what if the evening star were a different star other than the morning star?” isn’t as straightforward a question as I thought “what if c were to change” would be. ---
**Author:** ![The\_Tao\_s\_Revenge](https://avatars.discourse-cdn.com/v4/letter/t/73ab20/32.png) [@The\_Tao\_s\_Revenge](https://boards.straightdope.com/u/The_Tao_s_Revenge)\ **Post date:** [September 13, 2011, 1:19am UTC](https://boards.straightdope.com/t/what-happens-if-c-decreases/595832/22 "2011-09-13T01:19:48Z")
> [@Frylock](#): > > Fair enough==“c=x” for any x, you’re saying, is exactly as meaningful, no more no less, than “1=1.” > > But 1=1 is a tautology, which, while not meaningless, is uninformative. > > But c=x (for any x other than c) is informative. > > It seems like you’re saying “The evening star is the morning star” is exactly as meaningful as “venus is venus”. But of course this would be false. > > On the other hand, asking “what if the evening star were a different star other than the morning star?” isn’t as straightforward a question as I thought “what if c were to change” would be. Basically if I understand correctly, and my mind has some fresh new knots, they’re saying c is kind of like a ratio of space to time. If c changes then maybe space or time changed, and there’s no way to tell because the rulers and clocks could have changed with it. ---
**Author:** ![Asympotically\_fat](https://avatars.discourse-cdn.com/v4/letter/a/e47c2d/32.png) [@Asympotically\_fat](https://boards.straightdope.com/u/Asympotically_fat)\ **Post date:** [September 13, 2011, 7:45am UTC](https://boards.straightdope.com/t/what-happens-if-c-decreases/595832/23 "2011-09-13T07:45:08Z")
Be aware though that it’s its relationship with other constants that’s important. By my reckoning if you decrease c by swome factor then gravity becomes weaker by a (generally) much larger factor. ---
**Author:** ![Chronos](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/chronos/32/134_2.png) [@Chronos](https://boards.straightdope.com/u/Chronos)\ **Post date:** [September 14, 2011, 2:59am UTC](https://boards.straightdope.com/t/what-happens-if-c-decreases/595832/24 "2011-09-14T02:59:48Z")
> [@](#): > > Be aware though that it’s its relationship with other constants that’s important. By my reckoning if you decrease c by swome factor then gravity becomes weaker by a (generally) much larger factor. That depends on how you’re defining “c decreasing”. Though I can’t offhand think of any dimensionless constants which involve both c and G-- Ratio of the Planck mass to the proton mass, maybe? [Previous page](https://boards.straightdope.com/t/what-happens-if-c-decreases/595832.md?page=1)