How is it possible to determine when “now” is? From what I understand time is like a river and once you walk into it you cannot walk into the same river again. It seems as though as soon as you are consciously aware of a “now” it becomes then.Any help out there would be appreciated.
This is just a WAG …
"This time, called the Planck time (Gh/c5)1/2, equals approximately 10^-43 second …
Real spacetime, in accordance with this picture, has 26 or 10 spacetime dimensions, but all of these dimensions except the usual four are somehow compacted or curled up to a size comparable to the Planck scale. Thus has the existence of these other dimensions escaped detection."
Which seems to imply that “now” is about up to 10^-43 second after you have thought it.
You’re asking a physics/philosophical question that - believe me - has no easy answer. Speaking for myself, I find time is better spent thinking about tangible things (such as beer brewing techniques) than pondering such mind-blowing concepts as time.
By the time you know that it is “now”, it is “then”.
Was that clear?
Maybe to you, but even the OP seems to have recognized that “now” would be such a time as the river was unaffected, e.g. still the same. Also, how long after you recognize the “now” is the “then”, or are you saying they happen simultaneouly in you mind?
Wasn’t it Steven Hawking who said that the only difference between the past and the future is which one we remember?
Strolling away, whistling
It seems to me that there may or may not be a real “now”; if there is, it seems to me to be imperceptible by the human brain. But there’s definitely an apparent, or metaphorical, “now” that is a sort of social construct. Since it’s not real, it doesn’t have to be precisely perceived or defined, it seems to me. We just have to know what we’re talking about – to define the degree of precision for the “now” I happen to be referring to in any particular conversation.
But everything you observe is some event that happened in the past. Now is what you are now observing, not what is now taking place because it is impossible to observe that.
(Watching “Spaceballs: The Movie”. They reach “now” in the movie.)
Dark Helmet: What the hell am I looking at? When does this happen in the movie?
Colonel Sandurz: You’re looking at now, sir. Everything that happens now is happening now.
Dark Helmet: What hapened to then?
Colonel Sandurz: We passed then.
Dark Helmet: When?
Colonel Sandurz: Just now. We’re at now now.
Dark Helmet: Go back to then.
Colonel Sandurz: When?
Dark Helmet: Now!
Colonel Sandurz: Now?
Dark Helmet: Now!
Colonel Sandurz: I can’t.
Dark Helmet: Why?
Colonel Sandurz: We missed it.
Dark Helmet: When?
Colonel Sandurz: Just now.
Dark Helmet: When will then be now?
Colonel Sandurz: Soon.
Where were you before you walked into it? Near as I can figure, we’re all born on a boat that’s going downstream.
If you’ve figured out a way to stand outside of space-time, you probably don’t need to be concerned with mere mortal matters like what to call “now” or what a bunch of shmoes on the Internet think about it.