[fargolime]

I've seen many people say that, but none who proved it scientifically. After all, it simply uses generally accepted equations to make its point. As the author suggests, I've plugged the equations into Excel to get the same charts.

My favorite part is this:

- The Relativistic Rocket site reports that a rocket accelerating / decelerating at 1 Earth gravity can travel from Earth to the Andromeda galaxy, 2 million light years away and arriving at low speed, in 28 years on the crew’s clock. Then the rocket’s crew would observe a beacon floating at the midpoint between the galaxies recede 1 million light years in the 14 years after they pass it.

That's an unassailable conclusion, and it follows that the beacon would accelerate away from the crew as they observe, since the beacon moved away from them at an average rate greater than that the rate at which they passed it. That's the explanation for dark energy in a nutshell.

[mikeash]

Since 1 million light years in 14 years is way faster than the speed of light, and relativity doesn't allow you to exceed the speed of light by acceleration, clearly this is something other than regular old F=ma "acceleration".

Additionally, the fact that we don't see things 14 light years away accelerating to a million light years away very quickly, despite being under a constant 1 gee acceleration, would seem to indicate that this is not what actually happens.

Putting numbers into equations and getting other numbers out doesn't mean anything by itself. I can use the standard d = 1/2at^2 equation to "demonstrate" that combining one apple and three tangerines produces 4.5 dandelions, and you would get the same result putting those numbers into the equation, but it doesn't mean the exercise makes any sense.

I will be honest: I don't understand enough about physics to point out exactly what is wrong with the proposed theory. But I understand enough to realize that it is very wrong, and point out some obvious flaws.

Finally, since the equations are well understood, if this really does explain "dark energy" then it should be possible to put in real-world numbers for things like the gravitational field of the Earth and get numbers out for the accelerating expansion of the universe which match real-world observations? Has the author actually done this and compared the results with observations? I can see no indication of this, even though it should be an easy exercise. This is another major indication that this is all nonsense, if it is in fact the case that this analysis has not been done.

[fargolime]

> Since 1 million light years in 14 years is way faster than the speed of light, and relativity doesn't allow you to exceed the speed of light by acceleration, clearly this is something other than regular old F=ma "acceleration".

As the blog notes, the speed of light limit in relativity theory applies only to observers in free fall or observers measuring things passing right by them. The rocket's crew isn't in free fall and the thing they're measuring is distant.

> Additionally, the fact that we don't see things 14 light years away accelerating to a million light years away very quickly, despite being under a constant 1 gee acceleration, would seem to indicate that this is not what actually happens.

That's because our 1g field drops off quickly with distance. The rocket's crew has a uniform 1g field all the way to the beacon.

> I can use the standard d = 1/2at^2 equation to "demonstrate" that combining one apple and three tangerines produces 4.5 dandelions, and you would get the same result putting those numbers into the equation, but it doesn't mean the exercise makes any sense.

That's because you're using the equation illogically, by mixing labels. The blog uses the equations properly.

> But I understand enough to realize that it is very wrong, and point out some obvious flaws.

OK, I've been a student of the blog for years and can likely always show the flaw in your arguments.

> I can see no indication of this, even though it should be an easy exercise.

It wouldn't be easy. As the blog notes, it's not just the Earth's gravitational field, it's also the Milky Way's and more. When observing supernovae in distant galaxies we're talking about a much larger g-field than the Earth's.

> This is another major indication that this is all nonsense, if it is in fact the case that this analysis has not been done.

That's unscientific as hell, like saying Newton's Principia is crap because he didn't include a calculation that used his equations to weigh the Earth (which Cavendish "easily" did much later).

[mikeash]

"It wouldn't be easy."

Nonsense. The mass of galaxies is reasonably well known. Put the numbers in and see how well they match reality. The numbers are uncertain? Then put on appropriate error bars and see if reality falls within them.

[fargolime]

We know the mass of each of millions of galaxies? I doubt the galaxies involved have even been counted. But never mind, because ideas aren't proven invalid when they aren't applied in some way you desired.

[mikeash]

No, but when a quantitative theory isn't compared with reality then there is absolutely no reason to pay attention to it until it is.

[fargolime]

Special relativity should've been tossed in the bin, then.