# Re: [humanism-174] Space travel according to Victor Stenger

 From: Tim C. Sent on: Friday, April 26, 2013 3:34 PM
Still all very relative.  Given the distance involved, such a slow acceleration and deceleration would very much negate the relativity/time effect.  In order to translate 2400 years into 14 or 28, the speed of light would need to be approached long before this idea posits!

Tim

In a message dated 4/26/2013 3:22:37 P.M. Eastern Daylight Time, [address removed] writes:

Okay.  Cool.  Your ultimate goal here is to stop when you get there, right?  So, you start at a constant acceleration: moving a little faster every second until you're halfway there.  Then you start slowing down for the rest of the trip.  So, it takes the same amount of time to speed up as it does to slow back down.  In this case, seven years speeding up and then another seven slowing down.

On Apr 26,[masked]:41 PM, "sheri presloid" <[address removed]> wrote:
N
ow that is cool, Rick.  I see what you are saying there, but if they are talking about slowing down, how is it that it takes 7 years to get to the half way point, BUT it will still be 7 years to reach the destination if you slowed down at the halfway point?

I hope I worded that right.

Eeeek!  I think I actually understand my own question! ha

On Fri, Apr 26, 2013 at 2:36 PM, Rick wrote:

It's the acceleration.  He's saying that the force of the acceleration would make "down" the direction of the engines as a consequence of the whole equal and opposite reaction business.
You accelerate at 32 feet per second squared (1g) until you hit the halfway point.  Then you have to spend the rest of the trip slowing back down.  So, you turn the ship around and decelerate at 32' per sec sq, and it will continue to feel like 1 gravity.
The only time you're weightless is at the turn around because that's the only point when your velocity is constant.  Easy.

On Apr 26,[masked]:00 PM, "Tim Campbell" <[address removed]> wrote:
In a message dated 4/26/2013 1:27:44 P.M. Eastern Daylight Time, [address removed] writes:
I'll jump on someone's shoulders to see ya Tim! ha

Again, my head is spinning without layman terms, but what does this mean:

Of course, the ship can't continue to accelerate, since it needs to be moving at the same speed as the planet when it arrives. When it reaches the halfway mark at 600 light-years from Earth, the crew turns the ship around so it then decelerates at one g for the remainder of the trip. Those onboard notice no change. They continue to experience the equivalent of gravity on Earth.

I don't get it....

To be honest, I am not certain what he is talking about here either!  "One g" is basically the gravitational force that we feel here on Earth.  We use our "g" as the reference point for gravity anywhere else in the universe! If you weigh 100 pounds on earth, then on a planet with a gravity of 2g you would weigh 200 pounds, and so on.

But g forces have nothing to do with speed or acceleration once you are in space.  Once you have escaped earth's gravitational force, you would be essentially weightless unless your ship did something to give you an artificial gravity.  We see science fiction concepts of space stations being wheels for this reason. It is guessed that the wheel shape would be spun so that the centrifugal force would create a kind of gravity for the inhabitants.

I understand that he is positng a speed high enough to utilize the relativistic effects on time, but in order for a 2400 year trip to take 14 years in astronaut time, the ship must be coming very close to the speed of light.

The orientation of the ship would have nothing to do with the acceleration or deceleration or on-board gravity. however, if the speed is changing, then that change WILL have an effect on the relativistic effect as well.

Until a speed of appr 670 MILLION MILES PER HOUR is technically feasible, any journey to another solar system will involve either multiple generations or some form of suspended animation/hybernation for the crew.

Of course, I will be discussing this in detail in July!

Tim

--
Please Note: If you hit "REPLY", your message will be sent to everyone on this mailing list ([address removed])
This message was sent by Tim Campbell ([address removed]) from The Cleveland Freethinkers.
To learn more about Tim Campbell, visit his/her member profile
Set my mailing list to email me As they are sent | In one daily email | Don't send me mailing list messages

Meetup, POB 4668 #37895 NY NY USA 10163 | [address removed]

--
Please Note: If you hit "REPLY", your message will be sent to everyone on this mailing list ([address removed])
This message was sent by Rick ([address removed]) from The Cleveland Freethinkers.
To learn more about Rick, visit his/her member profile

--
Please Note: If you hit "REPLY", your message will be sent to everyone on this mailing list ([address removed])
This message was sent by sheri presloid ([address removed]) from The Cleveland Freethinkers.
To learn more about sheri presloid, visit his/her member profile
Set my mailing list to email me As they are sent | In one daily email | Don't send me mailing list messages

Meetup, POB 4668 #37895 NY NY USA 10163 | [address removed]

--
Please Note: If you hit "REPLY", your message will be sent to everyone on this mailing list ([address removed])
This message was sent by Rick ([address removed]) from The Cleveland Freethinkers.
To learn more about Rick, visit his/her member profile
Set my mailing list to email me As they are sent | In one daily email | Don't send me mailing list messages

Meetup, POB 4668 #37895 NY NY USA 10163 | [address removed]

### Cleveland, OH

Founded Mar 8, 2007

Help support your Meetup

#### Our Sponsors

• ##### The Freedom From Religion Foundation

FFRF is the largest freethought association in North America!

• ##### The Northeast Ohio Coalition of Reason

The Northeast Ohio Coalition of Reason is a local chapter of UnitedCoR

• ##### Halcyon Lodge

Space for meetings, etc.

• ##### Northern Ohio Freethought Society

Free membership to 1st 20 people who become members of FFRF!

#### People in this Meetup are also in:

• ##### Life Is Short So Let's Have Some Fun Group!

3,903 members

• ##### Cleveland Natural Path is now The Heartfulness Center

394 Meditators

• ##### Cleveland Drumcircle Community

1,421 Hand Drummers

• ##### Center For Inquiry Northeast Ohio

799 humanists

• ##### West Side Markers Figure Drawing Group

918 Figure Drawing Artists

• ##### Everyday Spacer Cleveland

535 Everyday Spacers

## Sign up

Meetup members, Log in

By clicking "Sign up" or "Sign up using Facebook", you confirm that you accept our Terms of Service & Privacy Policy