How long does it take radio or TV waves to travel across our galaxy?
1. far? I don't understand the question 2. radio travels at the speed of light. if its true that the milky way's disk is 100,000 light years and we're 25,000 light years from the center then it would take about 75,000 light years to reach the other side of the milky way. 3. the andromeda galaxy shouldn't receive our signals because of attenuation at inverse square. I think the closest star to us (4.22 light years away) would receive 25% of the original signal sent on a normal towers wattage and frequency. 4. I don't know. 5. they are too far away we might be looking in the wrong place, they might not exist, they might be dead, they might know how to use radio yet, they might not even use radio, we might have over looked their signals "encryption" or pattern. we might have missed their signal by thousands of years we haven't spent enough time looking. (we've only done this for about 40 years) there might be too much cosmic interference there might be too much man made interference they are not directly broadcasting toward us.
Explain why radio waves can travel through space but sound waves cannot.?
Sound is caused by pressure waves in air (or something else, sound can go through water, for example). If there is no material (called a vacuum), there is no way for sound to travel, so you can't talk. Inside a space capsule or space station there is air, so the astronauts can talk there. All electro-magnetic radiation (which includes radio waves, microwaves, visible light, ultra-violet, x-rays, and gamma rays) will spread out with distance and will, at some point, become too dim to be observable. You can prove the radio wave part of it in your car. The reason why you can't hear San Francisco radio stations in New York City is because the signal gets weaker with distance. Radio waves are electromagnetic waves with a longer wavelength than visible light, but all electromagnetic waves travel at the speed of light in a vacuum (in matter they travel somewhat slower). Part 2 of your question... Satellites transmit radio waves from a sender to a receiver and because it takes time for the waves to travel, there is always some delay
2 physics questions: Wave Speed?
Ultra Violet is above 300THz. Tetra Hz. All radio waves travel at the speed of light. The wavelength of any radio wave is: Wavelength (λ) = Speed of light (v) divided by Frequency ( MHz). λ is the Greek letter lamda.
What kind of a wave can travel through empty space?
Electromagnetic, eg, light
How far do radio signals travel into space before they degrade to a degree beyond being possible to be detected?
That depends on how strong the signal was when it left Earth. As others pointed out, it just keeps getting fainter, until your receiver can’t distinguish it from the background noise. But let’s do a numerical example of something like a large broadcast station, radiating a megawatt.What’s the signal strength? Typically you’ll work in terms of a Watts/square meter/Hz of bandwidth - Let’s assume that the station has 10 kHz bandwidth - so it’s radiating 100 Watts/Hz. That spreads as a sphere with surface are 4*pi*r^2.So, at 1 million km (not too far away), the sphere is about 12.6E18 square meters - the spectral flux density is then 100/12.6E18 W/Hz/m^2 -> 7.95E-18. (-171 dBW/Hz/m^2)Now, let’s ask “what’s the smallest signal we can detect against the noise?” In general, you’re going to be working against the cosmic background radiation, which varies with frequency - but a good approximation is to assume it is at 3 degrees Kelvin and uniform in all directions: Boltzmans constant is 1.38E-23, so multiplying that out we get about 4E-23 W/Hz/m^2 or -224 dBW/Hz/m^2.So, at a million km, the radio station is 53 dB stronger than the background noise.So let’s move farther away - it goes as inverse square, so if we move out by a factor of 1000, to a billion (1E9) km from earth, the radio station is now at -231 dBW/Hz/m^2, which is below our noise by about 7 dB. This would make it very difficult to detect.Now, if you wanted to make a signal that can be detected easily, you’d make a very narrow band transmission - Above, I assumed the radio station was essentially random noise with 10kHz BW. If we transmit just a narrow carrier (<1 Hz wide), then we pick up another 40 dB. So at a billion km, we’re now at -191 dBW/m^2, compared with -224 dBW/m^2. If we go out to the Kuiper belt, where things like Pluto are, that’s at 6E9 km, and our signal is another 15 dB weaker (-206 dBW), but still detectable. Out at 200 AU (3E10 km), we’re starting to get close - the signal is -220 dBW, and the noise is -224.But, if you go out to Proxima Centauri, 4.4 light years, or 4.16E13 km (that’s about 41,600 billion km), the signal has faded to way below the noise floor.
Why does light (electromagnetic wave) traveling through space become weaker by distance?
The energy is not being lost. It is being spread out. Just like noise sounds quieter when you're farther away because the sound spreads out, when you're farther from a light it will seem dimmer because it's going out every direction.