16
   

The Fermi Paradox

 
 
Olivier5
 
  2  
Reply Tue 19 Dec, 2017 05:36 am
@Krumple,
https://upload.wikimedia.org/wikipedia/commons/5/58/BertozziExp.svg
Data of the Bertozzi experiment show close agreement with special relativity. Kinetic energy of five electron runs: 0.5, 1, 1.5, 4.5, 15 MeV (or 1, 2, 3, 9, 30 in mc²). Speed: 0.752, 0.828, 0.922, 0.974, 1.0 in c² (or 0.867, 0.910, 0.960, 0.987, 1 in c).

Bertozzi experiment:
an experiment specifically aimed at demonstrating the relativistic effects in a very direct way was conducted by William Bertozzi (1962, 1964).[10][11] He employed the electron accelerator facility at MIT in order to initiate five electron runs, with electrons of kinetic energies between 0.5 and 15 MeV. These electrons were produced by a Van de Graaff generator and traveled a distance of 8.4 m, until they hit an aluminium disc. First, the time of flight of the electrons was measured in all five runs – the velocity data obtained were in close agreement with the relativistic expectation. However, at this stage the kinetic energy was only indirectly determined by the accelerating fields. Therefore, the heat produced by some electrons hitting the aluminium disc was measured by calorimetry in order to directly obtain their kinetic energy - those results agreed with the expected energy within 10% error margin.

https://en.wikipedia.org/wiki/Tests_of_relativistic_energy_and_momentum#Bertozzi_experiment
Brandon9000
 
  -1  
Reply Fri 22 Dec, 2017 04:48 pm
@Olivier5,
Olivier5 wrote:
As you must know, this is correct in Gallilean mechanics but not in Einstein's relativity, which states that it would take infinite energy for any mass to reach C. Assuming an interstellar spaceship could possibly reach 1/2C for a 1/3 of its trip (acceleration time 1/3 of trip length, 1/2C for 1/3, and deceleration for 1/3) , a trip of 10 lightyears would take what, 30 years to complete?

I used only the definition of acceleration. I didn't comment on the degree of difficulty doing it.

For constant acceleration:

a = (v2 - v1)/(t2 - t1)

This is a definition and, therefore, always correct.

The calculation I gave is correct according to the definition of acceleration, other than the fact that you cannot actually reach the speed of light. If you prefer, consider the time I gave to be the time required to reach 99.99% the speed of light if you were able to maintain an acceleration of 9.8 m/s^2, which, of course, would be tantamount to impossible. Indeed, if you were able to maintain this acceleration up to 99.99% of the speed of light and do the same in decelerating, a trip of 10 light years would take about 12 years from the point of view of an Earth bound observer. From the point of view of the travelers, it would take a much shorter amount of time, per the equations for time dilation.
cicerone imposter
 
  1  
Reply Sat 23 Dec, 2017 01:09 pm
@Olivier5,
Doesn't heat and humidity make a difference?
gungasnake
 
  -1  
Reply Sat 23 Dec, 2017 11:52 pm
@oralloy,
The claims I read about Biefeld/Brown propulsion indicate that superluminary speeds should be fairly easy with it. Relativity, of course, is a pile of **** just like evolution; there is no basic law of physics to prevent superluminary speed.
Olivier5
 
  1  
Reply Sun 24 Dec, 2017 03:39 am
@cicerone imposter,
A difference to what?
Olivier5
 
  1  
Reply Sun 24 Dec, 2017 03:38 am
@cicerone imposter,
A difference to what?
0 Replies
 
rosborne979
 
  1  
Reply Sun 24 Dec, 2017 11:18 am
@gungasnake,
It’s times like this that I wish your views held some credibility.
cicerone imposter
 
  1  
Reply Sun 24 Dec, 2017 04:41 pm
@Olivier5,
Kinetic energy. https://www.reference.com/science/temperature-relate-kinetic-energy-c7c65dcf5fe026bbhttps://www.reference.com/science/temperature-relate-kinetic-energy-c7c65dcf5fe026bb
gungasnake
 
  -1  
Reply Mon 25 Dec, 2017 11:02 am
@rosborne979,
One take on what is more or less known:

http://www.bearfabrique.org/Misc/electrogravitics.pdf
0 Replies
 
Olivier5
 
  1  
Reply Mon 25 Dec, 2017 05:54 pm
@cicerone imposter,
These things (accelerating particles) are done in a vacuum. And in a vacuum, there, no water vapor and almost no heat to speak of.
cicerone imposter
 
  1  
Reply Mon 25 Dec, 2017 06:36 pm
@Olivier5,
If they are done in a vacuum, what value does it have?
oralloy
 
  -1  
Reply Mon 25 Dec, 2017 06:44 pm
@cicerone imposter,
cicerone imposter wrote:
If they are done in a vacuum, what value does it have?

Humanity gets to explore and learn about other planets/star systems. And one day in the distant future, hopefully colonize them.
0 Replies
 
oralloy
 
  -1  
Reply Mon 25 Dec, 2017 06:50 pm
@gungasnake,
gungasnake wrote:
The claims I read about Biefeld/Brown propulsion indicate that superluminary speeds should be fairly easy with it. Relativity, of course, is a pile of **** just like evolution; there is no basic law of physics to prevent superluminary speed.

I don't think we're going to be able to exceed the speed of light. No matter what method someone comes up with to get around it, I think the universe is always going to step in and say "nope".

But in a way that's a good thing. The speed of light can prevent a vastly more powerful alien race from coming to wipe us out.
0 Replies
 
Olivier5
 
  1  
Reply Tue 26 Dec, 2017 03:53 am
@cicerone imposter,
The value of fundamental research about how the universe works. Eg here, testing the theory that the speed of light is a sort of limit, a speed impossible to surpass by any object of any dimension.
0 Replies
 
Olivier5
 
  1  
Reply Tue 26 Dec, 2017 04:15 am
@Brandon9000,
What's not correct in your reasoning is thecidea that a constant acceleration can be obtained by a constant propulsion force (engine thrust). That's only true in classic mechanics, but in Relativity, the mass of an object increases as its speed becomes significant relative to the speed of light, ie when the quotient V/C is not negligeable.

If the relativist mass of a spacecraft increases with speed, the engine thrust you need to maintain constant acceleration also increases with speed. And the theory predicts that to reach the speed of light would require an infinite amount of energy, because the object's relativist mass would become infinite, reason for which an object with any mass cannot reach the speed of light.
Brandon9000
 
  -1  
Reply Tue 26 Dec, 2017 04:11 pm
@Olivier5,
Olivier5 wrote:
What's not correct in your reasoning is thecidea that a constant acceleration can be obtained by a constant propulsion force (engine thrust). That's only true in classic mechanics, but in Relativity, the mass of an object increases as its speed becomes significant relative to the speed of light, ie when the quotient V/C is not negligeable.

If the relativist mass of a spacecraft increases with speed, the engine thrust you need to maintain constant acceleration also increases with speed. And the theory predicts that to reach the speed of light would require an infinite amount of energy, because the object's relativist mass would become infinite, reason for which an object with any mass cannot reach the speed of light.

I neither said nor implied that a constant acceleration can be obtained by a constant propulsive force.
Olivier5
 
  1  
Reply Wed 27 Dec, 2017 07:37 am
@Olivier5,
Posters voting down facts... I guess that will make facts go away?
0 Replies
 
Olivier5
 
  2  
Reply Wed 27 Dec, 2017 07:38 am
@Brandon9000,
My bad, you indeed didn't imply that.
0 Replies
 
 

 
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