Hacker News Reader

Comment by Vysero | Hacker News Reader

The idea that aliens would use these to propel ships is rather ludicrous, and highly unlikely. The nearest galaxy is 25k light years away so even at the maximum speed it would take 25 thousand years to travel here.

That being said, it must be something exceptionally energetic.. wish I could see it.

View on HN

Why do you assume they need to travel between galaxies? They could be going to the next solar system over and we're simply seeing the leakage of their propulsion. Just because the light travels across galaxies doesn't mean it's purpose is to travel across galaxies. Moreover, a species that can unleash this much energy has probably conquered such things as mortality and age related decay.

That's a good point perhaps I jumped to conclusions.

you also assume they're traveling AT or NEAR light speed, they could be traveling many times that OR not traveling via speed at all, but warping space and literally folding it over on itself and going THROUGH space like basically creating a controlled wormhole.

No they couldn't actually. You didn't read the article.. here it is:

https://www.space.com/35996-fast-radio-bursts-powering-alien...

the suggestion is that they would be gathering the waves in a light sails. Also you can't travel faster than light, end of story. Warping space or traveling through "wormholes" is not faster than light travel.

If somebody edit the exact speed of light, he could claim faster than light!

Oh man, I don't want to get into an argument on HN. But you didn't really read the previous comment with a generous eye. The poster never mentioned "faster than light" travel at all. In fact, they specifically called out AT or NEAR light speed, and then gave wormhole travel as an example of "not traveling via speed".

gremlinsinc literally said "they could be traveling many times that" in respect to "AT or NEAR light speed." As in they could be traveling many time faster than light. He didn't use the exact phrase "faster than light" but his meaning is pretty clear.

Transportation technically is faster than the speed of light, because if travelling at the speed of light you get to point B in 5 years, and by using a warp drive/worm hole device you get their in 3 days, you've traveled faster than light, doesn't matter if you cheated using physics, you still got their in a fraction of the time. Sure you're 'speed limit' didn't exceed the speed of light, but the distance/normal travel time DID exceed the speed of light, so it's just semantics.

Mortality is a feature not a bug.

It's a feature for the genes, it's an anti-feature for the individual organisms.

> The nearest galaxy is 25k light years away so even at the maximum speed it would take 25 thousand years to travel here.

Given your arithmetic, I assume by "maximum speed" you mean the speed of light, in which case travel wouldn't take 25k years. It would in fact be instantaneous. At relativistic speeds, distances contract and time dilates.

Now, this is all moot because this:

> The idea that aliens would use these to propel ships is rather ludicrous, and highly unlikely.

... is absolutely correct. No amount of energy will propel a massive object to the speed of light.

edit: I realized I may have misinterpreted. From the perspective of someone watching their own kind travel that expanse, it would indeed appear to the outside observer to take 25k years to travel.

Plus reaching the speed of light requires infinite energy, literally. You have to settle on some small fraction of the speed of light, depending on how much mass and energy you have.

It's pointless to travel at speed of light to get instantaneous travel when you spend half an hour boarding rocket and 2h in traffic from the city to starport.

And you have to stow your laptop for the duration of the instantaneous flight

It's only instantaneous for you. Anyone not on the light speed rocket will be dead by the time you deboard on the other side.

As long as we're being pedantic, the trip is only instantaneous if you're able to instantly accelerate to c. Otherwise, it would take around two years for the occupant (one year to accelerate to c upon departure and another to decelerate on arrival), assuming acceleration at 1G.

Ahem. To add yet more pedantry, one year of acceleration at 1G doesn't get you to c, but only fairly close. (I worked that problem nearly 40 years ago, so my memory of "how close" is a bit obscure.)

Maybe they live one billion years, or 10 million times more than us. These 25,000 years for them would be less than a day for us. Just saying :)

>> The nearest galaxy is 25k light years away so even at the maximum speed it would take 25 thousand years to travel here.

We're talking about aliens, right? Who says they must have human life spans? Perhaps a 25k year trek is a walk in the park for them.

I find this assumption (that life on other planets will have the same duration as life on Earth) very often in discussions of possible discovery of or interaction with alien civilisations. It is a huge assumption, on par with assuming that aliens must have a head, two hands and two feet and communicate by making sounds, like we do.

Accordingly, the fact that we are limited in our ability to travel from star to star because of short duration of our life spans relative to the speed of light, is not to be taken for granted as a universal characteristic of all life in the universe.

I think it's extremely unlikely to be aliens, since each time in the past something like this has come up a non-aliens explanation has been found.

That said, I don't think distances/timescales is a great argument against aliens, since it makes a lot of assumptions. They could use robotic ships, or generation ships (no telling how long their generations might last.) If they're moving at a significant fraction of the speed of light, relativistic effects could be dramatically reducing their perceived mission duration. Maybe the biology of their species is such that cloning or suspended animation is straight forward.

Reply on news.ycombinator.com