View Full Version : Question: Huge Radio Dish To detect weak broadcasts in milkyway

2018-Nov-28, 08:42 AM

I'm an ordinary person with very limited knowledge about physics, astronomy etc. But i'm always amazed with the science and engineering brought to us by the clever minds. Real game changers of humanity are our engineers and scientists. But without popular support of humanity, they wont get the money to spend on stuff to enlighten us. I believe we have the potential to be space faring civilization since late 1960s. Although exciting events are about to come (like positioning james webb telescope, building reusable rockets etc.), actually there's whole lot of practical (not theoretical) stuff to test in space. For example a huge centrifuge, nuclear propulsion etc. This is my basic thought on where we are on space exploration.

Here's my question:
1. Afaik strength of radio waves decay as the distances increase. Our, for example tv broadcasts in 1960s will reach a star for example 1000 ly away in year 2960 but it will be very weak to detect. If, for example, there's an advanced pre-ftl civilization on a system 1000 ly away that builds a huge radio receiver like 1000 km diameter in space; would they be able to watch 1960s tv broadcasts? If yes,
2. If we build a huge dish antenna on the moon like one in puerto rico, would it be able to detect tv broadcasts of alien civilizations? If yes,
3. If ftl is still not a practical technology for milkyway civilizations, would it be feasible to communicate other civilizations with radio waves? Would there be sublight speed expeditions to other stars in our current tech level? How would it be feasible to trade with civilizations like 100 ly away. Only knowledge sharing? Or if they have abundant amount of gold for example, and we have stuff that they lack of; would it be practical to transport raw materials between different star systems? If they're like 100 ly away, it would take lots of time to request some stuff, delivery time etc.

if someone will be able to find ftl technology in our galaxy other than humanity, would they share their ftl technology to the pre-ftl civilizations through primitive communication technologies, such as radio broadcasting of high tech ftl?

2018-Nov-28, 11:49 AM
1. No, our TV signals are too weak to be coherent. They'd be lost in background noise long before they reached 1000 LY. However, TV broadcasts are not designed to cross interstellar distances. A signal designed to, such as a strongly concentrated high power tightbeam, might reach longer distances intact.

2. See above answer.

3. Interstellar travel is a major effort at any tech level. And no, transport of material goods across such distances is not feasible. It's always going to be far cheaper and easier to mine or manufacture stuff in your own solar system than to haul it to even the nearest stars. Even communication across 100 LY is non-trivial.

As for FTL, as far as we can determine it violates the laws of physics. If it can be done, one signal won't tell us how to do it; it would require an overall advanced society to accomplish.