Shouldn't we have heard alien radio signals by now? Why not?

Ryan_m_b

Absence of evidence is not evidence of absence. You are making a fallacious statement when you claim that we are first.

Orion1

Most humans underestimate the vastness of space-time.

Watch this video and pay close attention to time index 2:35 to 2:49, the extent of humanity's first radio signals to scale with the Milky Way galaxy. This should provide some indication as to just how difficult it is to detect an artificial transmission, even within our own galaxy, let alone any artificial transmission from another galaxy.

Reference:
The Known Universe by the American Museum of Natural History - YouTube

Ryan_m_b

Very cool! Can anybody tell me the reason as to why the areas of the universe we have mapped extend from Earth in a sort of double fan shape rather than a sphere?

Orion1

Watch the TED lecture by astrophysicist George Smoot. The short answer is that this is the limit of the present galaxy sky survey data which must be mapped and cataloged.

Reference:
George Smoot: The design of the Universe

Ryan_m_b

Very interesting. Thanks

Drakkith

That was awesome!

Flustered

Do all intelligent civilizations evolve like we do? Do they all go through the same technology advances we do? What if another life form, had technology in totally different ways than humans, but they were still type 0 or 1 civilizations like us? Is it possible for life forms on the other side of the universe to have different elements and particles from us? Could their periodical table have more elements?

Flustered

Also could someone elaborate on the this question.
I once heard that not every galaxy can even harbor life, my teacher told me that only spiral galaxies can have life. Other galaxies cannot have life because they are not spinning there for new stars are not being born, or something to that extent.

DaveC426913

We don't know.

Probably there are some considerable differences, but we kind of assume a certain amount of convergent evolution in both biology and technology. (Not the kind that leads to bipedal axial symmetry, but the kind that leads to physical multi-cellular bodies with sensors, organs and brains, as well as a desire to observe the "thousand point of light" in the night sky.)
They might be made of different elements than us, though those elements will still be from our periodic table

No.

meh.

There are arguments that they may harbor less life than life as we know it, but it's pretty speculative.

Ryan_m_b

Evolutionary processes are the same whether or not it is life in the Earth's oceans or dots on a simulator but that doesn't mean they have to be anything like us physically or socially (beyond the need to be able to reproduce with variation to evolve and have the faculties to innovate and build/use tools).

There's little reason to believe that they will have the same technology though they may develop similar solutions to similar problems. It all depends on what natural and social problems they attempt to overcome, what resources they have to do it and what their psychology and culture permit.

This is speculation (albeit logical) and doesn't really mean much until we have more than one tool-using species that we would judge equivalently intelligent to compare ourselves with.

Flustered

Is it a given that a type 1 civilization can only get there if math is involved, math is a big part of physics and what not. Is it possible for a civilization to get farther than us without math? Also would they have the same concepts as us? Would they need to use negative numbers like we do? Could they advance farther without language?

Michio Kaku was saying that star wars would be a type 3 civilization, is it even possible for all those different life forms to be living in the same galaxy at the same time and fighting one another. I know it is SCI FY but what are the chances? Also Kaku was talking about civilizations taking all of their power from the stars, how would a civilization begin to take solar power from all the visible stars and use it?

Ryan_m_b

The kardashev scale isn't a scientific proposition, it's an idea that doesn't entirely make much sense. The idea being that type 2s have the capability to build dyson spheres and a type 3 simply does this to all stars in the galaxy, but there is no reason to think that there is an absolute path that a tool-using, sentient race would follow this scale. Regarding mathematics it would be pretty important, you can't produce any good science, economics or even politics without it and it would most likely be similar.

Flustered

Off topic//

Our all galaxies the same age? And has any galaxies that we know of, started to "die" or are "dead".

Flustered

Problems with this video, how can we map 360 degrees the CMB, but not 360 degrees of all the galaxies in the universe?

He also didn't explain what in our galaxy is blocking us from mapping the voids, nor did he explain why telescopes can't do it either.

He also said our galaxy is on the "boonies" not at the CENTER of the universe, he was implying that there is a center of the universe, he said it as clear as day.

In another thread, everyone is saying there is no center, but he said different.

Flustered

Is there a connection between the formation of galaxy superclusters, and the human brain cells. They look a lot alike.

DaveC426913

All galaxies are not the same age, no. But galaxies won't really die. Galaxies are just collections of stars. I suppose in principle a galaxy could be composed of nothing but dead stars...

No. Not in any but the most basic ways in mechanics of shapes. (A bubble and a star are both spherical but only because they are both comprised of competing symmetrical inward and outward forces).

Drakkith

The CMB is a much longer wavelength than visible and infrared light and is able to penetrate through large sections of our galaxy to be seen, whereas most of the visible light is blocked by dust. It is also very very smooth and is fairly easy to capture a large portion of the sky. In contrast, the vast majority of galaxies require a very high magnification and multiple hours of exposure time to see properly. This puts constraints on how much we can map with the few telescopes we have that can even see them. As an example, consider the Hubble Deep Field and Hubble Ultra Deep Field images. They requires DAYS of exposure time just to capture a very very small area of the sky.

If you go to the video again, you can see that he said we were not at the center of our Solar System, Galaxy, and Cluster, not universe.