Naked Science Forum
Non Life Sciences => Physics, Astronomy & Cosmology => Topic started by: Cyran on 29/01/2015 02:22:18
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Hi
Let me start of by saying that I have next to no knowledge in the field of physics which you will probably notice by my questions. Please dont flame me as a troll :)
1. Most of us think the sun is yellow/orange but if we where in a spaceship close to it we would just see that it was white so what would the rest of universe objects look like? Nebulas, galaxies, quasars etc would they too have different colors then what we are used to seeing from pictures and telescopes?
2. Is there a possiblity that our distance measurments of stars and galaxies are totally wrong? You can never be as sure of those calculations as the fact that 1+1 = 2. To me distance of stars and galaxies is far from fact and shouldnt be stated as such. What if the methods of calculating them is wrong or lacking in some way? The numbers could be way of or they could be close but not close enough to be stated as fact in textbooks.
This site is clamining that astronomers are way of in their calculations. Way to complicated for me though so I hope someone can take a look at it.
http://www.deceptiveuniverse.com/Distance-to-the-stars.htm
3. If you started a 50 light-year journey at the age of 20, traveling at 99.9% of the speed of light, would you look like 70+ years old when you arrived at the destiantion? How much would you have aged? And how would you experience the time on the spaceship? Would it feel like 50 slow years passing on earth or would it feel like just a day or two has passed?
Thanks for reading and I hope your answers will make me wiser :)
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Let me start of by saying that I have next to no knowledge in the field of physics which you will probably notice by my questions. Please dont flame me as a troll :)
Welcome to the forum!
1. Most of us think the sun is yellow/orange but if we where in a spaceship close to it we would just see that it was white...
That's not true. Where did you get that idea from?
2. Is there a possiblity that our distance measurments of stars and galaxies are totally wrong?
There's always a chance that a mistake has been made somewhere along the way. The question becomes how likely is it and its very unlikely.
3. If you started a 50 light-year journey at the age of 20, traveling at 99.9% of the speed of light, would you look like 70+ years old when you arrived at the destiantion?
The time dilation factor is 1/sqrt(1 - .9992) = 22.4. On a round trip it spending no time there it will take 100 years Earth time. However spaceship time will be 100 years/22.4 = 4.5 years. So you'd be 24.5 years old when you got home. It would feel like 4.5 years have passed for people on the spaceship.
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Welcome to the forum!
Thank you! :)
That's not true. Where did you get that idea from?
http://solar-center.stanford.edu/SID/activities/GreenSun.html
http://www.universetoday.com/18689/color-of-the-sun/
http://www.todayifoundout.com/index.php/2010/03/the-sun-is-white-not-yellow/
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Bonus Facts:
Light travels from the Sun to the Earth in about 8 minutes and 19 seconds.
While it only takes 8 minutes and 19 seconds for the light from the surface of the sun to reach us, it actually takes about 10,000-170,000 years for a photon to travel from the core of the sun to the surface.
A photon travel from the core to the surface? Actually? How do they sure?
They are no better than...
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While it only takes 8 minutes and 19 seconds for the light from the surface of the sun to reach us, it actually takes about 10,000-170,000 years for a photon to travel from the core of the sun to the surface.
That's because the photons don't move in a straight line. And to be precise, the photons that leave the core of the sun can't be said to be the "same" photons that reach the surface.
A photon travel from the core to the surface? Actually? How do they sure?
Nothing is 100% sure in any branch of science. Haven't you learned that by now? The book I gave you to read makes this clear. The book is Concepts of Modern Physics: The Haifa Lectures by Mendel Sachs. You can download it at:
http://bookzz.org/book/695697/7e974a
See also:
http://home.comcast.net/~peter.m.brown/ref/philosophy_physics.pdf
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A photon, if there is real thing called photon, will be absorbed instantly meets matter. Show me a photon passing a stone.
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A photon, if there is real thing called photon, will be absorbed instantly meets matter. Show me a photon passing a stone.
Buy me a diamond... big one preferably.
And I'll show you photons that pass through stone.
If you want to try granite...
Just let me choose the frequency.
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Light is em wave, em force pausing/vibrating in em field/space.
Electrons hit by the light/ force, jump out position, much like sound wave knock out dust on a speaker.
Is sound wave particle? Can we call it soundton?
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1. Most of us think the sun is yellow/orange but if we where in a spaceship close to it we would just see that it was white so what would the rest of universe objects look like? Nebulas, galaxies, quasars etc would they too have different colors then what we are used to seeing from pictures and telescopes?
White is perceived as all colors. So it would be best to say that our sun puts out all colors, red, green, violet, blue, UV, IR, and even X-Rays & Radio waves.
I'm not sure why the sun is often depicted as yellow, perhaps because it is a light color that isn't white. However, if one draws a curve of the spectral output of the sun, it peaks at about 5780 K, or about 501nm or 599 THz which puts it in the blue/green spectrum. However, depending on the time of day, it may change appearance, so at sunset, it may appear much redder.
Some stars spectrum peaks at a higher frequency, hotter temperature, shorter wavelength, and are classified as "blue", while others are cooler, and peak with lower frequency, longer wavelength which are classified as red.
Keep in mind, the surface of the sun is not uniform, and when plotted, say as intensity at various fixed frequencies, it has a very stormy look.
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Is sound wave particle? Can we call it soundton?
Within a solid, the minimum compression wave is called a phonon.
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Is sound wave particle? Can we call it soundton?
Within a solid, the minimum compression wave is called a phonon.
I have read that before, it involves heat transfer. We can also call it quannon, but do you think it is a particle?
Atoms vibrate to transfer heat, it is the force field of the charges vibrating, produce em wave. There is no photon particle produced.
Just my view.
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What is a photon if not an em wave? A phonon is not an em wave but a compression wave.
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very interesting site, but I see no reference to standard candles?
That's another way to define a distance. http://universe-review.ca/R02-07-candle.htm
For the naked eye I would expect the universe to be lighted by 'white' suns, if you're looking directly at them in space, preferably without a space suit. Different atmospheres will change the spectrum though, as will your definition of what color you see. Japanese often depict the sun as 'red' in their older works for example and that I guess is a result of their upbringing, westerners define it as yellowish I think.
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1. The color is in the eye of beholder. We see a mixture of full spectrum.
2. It is pretty possible lot science is not correct.
3. 1% light speed is dreaming, 99.9% is beyond crazy.
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1. Most of us think the sun is yellow/orange but if we where in a spaceship close to it we would just see that it was white
Your digital camera and your eyes have a function called "automatic white balance". As long as the light source has a reasonably broad spectrum, after a few seconds you will see it as "white", and be able to tell what colour various objects are under this light. (This ability does not work for narrow-band light sources like the orange sodium vapour lamps.)
Old film cameras had different kinds of film for "outdoors/sunlight", "incandescent light" and "fluorescent light". If you used the wrong kind of film (eg by walking indoors and taking a photo with your "outdoor" film), some of the colours could be badly distorted.
what would the rest of universe objects look like?
Professional astronomical telescopes only have black and white pixels, as this gives the highest resolution images with minimum "artifacts".
The astronomer rotates various filters in front of the sensor to pick up different colours (the same could be done with spectral splitters and 3 sensors).
These 3 images are then combined in software (adding colour to each black and white image) to produce the familiar colour JPEG image you see on the internet. These filters may not have exactly the same spectral response as the human eye, and so there is often a bit of interpretation or artistic license which goes on to produce a pleasing image.
Nebulas, galaxies, quasars etc would they too have different colors then what we are used to seeing from pictures and telescopes?
The human eye needs quite bright light to activate the cone cells which are sensitive to colour. So it is only planets like Mars or very bright stars like Betelgeuse and Sirius which have an obvious colour to the naked eye. Most other objects are only bright enough to activate the more sensitive rod cells (http://en.wikipedia.org/wiki/Rod_cell), which can only see black and white. If you could get close to some of these nebulae, I am sure it would look quite spectacular (until your eyes adapted).
If you take a long-exposure "star trail" image, you can see significant differences between the colour of different stars.
A large backyard telescope collects more light than your eye, and has more magnification which allows you to see some slight colour in Nebulae (assuming the city lights don't drown it out). But the most dramatic images are taken with a large telescope and an electronic sensor, using the triple exposure method described above.