Understanding General Relativity: Gravity Warping Space-Time

[Bobbyam]

Hi, I was an armchair student of physics some time ago, so I appreciate your patience with me. I was on a tour of the lost Atlantic Avenue tunnel in Brooklyn and I'm hoping someone can give me more insight, perhaps an analogy, to help me imagine this better. If I understood him right, this was mind blowing to me because for the first time I could glimpse actually understanding something of general relativity. The tour guide said that the heavier a locomotive is, the less energy is required to maintain its speed. This is because gravity is warping space time, like a bowling ball in a mattress, and the heavier locomotive, having more mass and more gravity, is actually "falling" through a space-time hole. Is this right? Can anyone add to it? Thank you.

 

[zhermes]

None of that is true, or even vaguely accurate. Sorry.

Most blatantly, the overall premise doesn't make any sense: the more massive a locomotive is, the more energy is required to keep it going---even neglecting high order effects (i.e. the details of the wheels, engine, air-resistance, wheel-track interface, etc).

For instance: how much energy does it take to keep a model train going? Is that more or less than a full size locomotive?

Now, as far as the general relativity: any GR effects for a locomotive staying on the surface of Earth would be extremely negligible. Like, extremely, extremely. Even more importantly, if---for some reason---GR effects were important, they would still make it harder to maintain a given speed for a larger mass.

 

[Bobbyam]

Thank you!

 

[Passionflower]

Hi, I was an armchair student of physics some time ago, so I appreciate your patience with me. I was on a tour of the lost Atlantic Avenue tunnel in Brooklyn and I'm hoping someone can give me more insight, perhaps an analogy, to help me imagine this better. If I understood him right, this was mind blowing to me because for the first time I could glimpse actually understanding something of general relativity. The tour guide said that the heavier a locomotive is, the less energy is required to maintain its speed. This is because gravity is warping space time, like a bowling ball in a mattress, and the heavier locomotive, having more mass and more gravity, is actually "falling" through a space-time hole. Is this right? Can anyone add to it? Thank you.

So, not knowing the situation, is this locomotive going down in a tunnel or traveling flat in a tunnel?

 

[Bobbyam]

It's supposedly on a perfectly flat grade.

 

[Passionflower]

It's supposedly on a perfectly flat grade.

In that case I fully agree with zhermes