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# Questions tagged [speed]

Questions regarding an object's movement, or its distance traveled relative to the time taken.

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0 answers
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### A spaceship travelling at speed of light [closed]

i am building an interstellar spaceship, which is capable of travelling at speed of light and it will be covered by an indestructible force field, that forcefield can absorb all forms of energy ...
1 vote
2 answers
117 views

### Determining the speed of meteor

How to determine the velocity of a meteor from two video data? I want to try to determine the orbit of the meteor, but before that I have to determine the meteor's entry velocity and apparent radiant ...
6 votes
2 answers
246 views

### Why do we say that gravitational waves travel at the speed of light, when they can escape a black hole and light cannot?

Or rather, does "speed" relate to the same measure? The speed of light is the speed of a photon/an electromagnetic wave in the empty space, but gravitational waves are wave of this very same ...
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4 votes
2 answers
5k views

### Why speed of light is considered to be the fastest?

According to Hubble's law, as things move further and further away from one another, there might come a point when their speed gets faster than the speed of light. So, why is it that the speed of ...
• 317
2 votes
0 answers
91 views

### Find position of orbiting body along orbit efficiently

I'm coding a game, and a fundamental mechanic is celestial bodies moving in elliptical, Keplerian orbits around a single gravitational point in a planetary system (not our solar system). The bodies ...
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0 votes
1 answer
238 views

### Space travel relative to solar system's movement through space

Assuming our entire system (stars, planets, etc) is moving through space at around 180,000 mph. Why can't we leave in a direction opposite our system's movement to achieve deepspace flight? Part two ...
3 votes
0 answers
69 views

### How do we know universe is expanding and not light slowing down? [duplicate]

We tend to take some things for granted, for example the light of speed is constant, but what if it isn't? How can we know that light is not slowing down at great distances for example, or that light ...
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4 votes
1 answer
161 views

### Is there something close to a consensus on Earth-Sun annual distance increase (speed)?

I've seen estimates varying by an order of magnitude, e.g. (New Scientist) Having such a precise yardstick allowed Russian dynamicists Gregoriy A. Krasinsky and Victor A. Brumberg to calculate, in ...
2 votes
1 answer
93 views

### Will Jupiter's days speed up?

Jupiter has so many moons, and those moons have a gravitational pull on it. Does that mean, that over time, the length of Jupiter's days will get shorter?
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14 votes
3 answers
7k views

### It takes light roughly 8 minutes to travel to Earth from the Sun, but based on which perspective?

The passage of time is relative depending on whether one is the stationary observer or the object/particle traveling at the speed of light (or close to it). I get this, kind of. But, when we talk ...
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1 vote
1 answer
340 views

### Calculate speed of a galaxy with redshift

I was going through some old exercises but I could never figure out who to solve this one The hydrogen absorption line (656 nm) of the galaxy NGC 77 is shifted by 41 nm into the reddish wavelength ...
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1 vote
2 answers
192 views

### If all objects move, where do we go?

Yes I know that the sun and planets in the solar system travel fast with an average speed of 448,000 mph. Are we going to the center of the galaxy? If so, does that mean our galaxy is getting smaller ...
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0 votes
2 answers
147 views

### Seeming conflict between most distant objects and age of universe (both estimated)

There was a recent article on bbc.com for laypeople like me titled "The mystery of how big our Universe really is", which prompted me to post the following question in their comments section ...
0 votes
1 answer
102 views

### Traversing a proton within the Planck time

If I could travel a super small distance (proton) in an even smaller time (Planck time), how long would it take me to cross the observable universe?
0 votes
1 answer
146 views

### can i use heliocentric velocity as a rotation speed? [closed]

In the research of the galaxies, does heliocentric velocity involves space's expanding velocity? and can i use heliocentric velocity by galaxy's rotation speed?
-3 votes
1 answer
131 views

### Can air/gas be slowed down by friction [closed]

Can wind/air that is moving at average speeds be slowed down by the cause of Friction? Also, Can Air bubbles in water be slowed down because of Friction? Please cite your sources.
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1 vote
1 answer
154 views

### Faster than light?

From what popular science tells us, if I travel at close to the speed of light, I'd age slower. So if I travel at 99% of SOL and travel the distance of one light year, for other people one year has ...
• 577
2 votes
2 answers
466 views

### How to find the mass of a planet not knowing the gravitational constant?

So I found this problem, I know the gravity of earth $g_0$, I found the orbital speed of one satellite using this equation $\frac{GM_em_s}{(R_e+h)^2}=m_sa$ ($M_e$ is the mass of earth, $m_s$ is the ...
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0 votes
1 answer
193 views

### how long a light year on earth will seem [closed]

First of all, sorry if this is not the right StackExchange to ask this question, but i don't know a better place (open to suggestion in case). So, the question: Suppose that for some reason, we can ...
0 votes
1 answer
648 views

### Absolute zero speed in space [closed]

I have read multiple posts in here about the concept of an absolute zero speed definition in space. However, I have some arguments FOR absolute zero speed, which I would like to write here, and have ...
1 vote
1 answer
534 views

### What would happen if you jumped out of a moving spacecraft? [closed]

I've watched a film where one of the characters claimed to have rapidly disembarked a moving spacecraft during a 5g burn (?!) and immediately wondered how he survived. For example, you're on a ...
• 165
3 votes
0 answers
61 views

### If the distance between galaxies is increasing and the speed of light is constant will the most of the light from the universe ever reach us?

Will the light from other galaxies ever reach us if the universe is expanding?
43 votes
5 answers
11k views

### Are photons aged?

If a star is at a distance of one lightyear, how old are its photons when they reach earth (from the photons’ perspective)? If time dilation is near zero at light speed, can we assume that the light ...
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1 vote
1 answer
171 views

### How fast does a spacecraft have to be to enter a primordial black hole without being torn apart?

If there really is a primordial black hole beyond the Kuiper belt, we can send a probe to the black hole and into it. But how fast must the probe be in order to enter the black hole without being ...
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3 votes
1 answer
70 views

### If interstellar medium was dense plasma and light slowed down, would things appear to move slower far away?

Voyager 2 recently left the solar system and registered an increase in plasma density. If light moved slower in this dense plasma, would it appear like events in other solar systems played out slower ...
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12 votes
4 answers
10k views

### Is Earth's Surface "In orbit"?

I'm having trouble understanding relative angular/tangential speeds at increasing altitudes above Earth's surface. In particular, I find this comparison of tangential velocities on Wikipedia very ...
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47 votes
2 answers
6k views

### Does the sun cross other spiral arms in its movement around the galaxy's center?

Today, Ansa.it released an article that states: [...]. In questo suo peregrinare galattico, il Sole ha attraversato anche i due bracci della Via Lattea Perseo e Centauro. "Sono zone di alta ...
6 votes
1 answer
377 views

### Have more recent LIGO/VIRGO gravitational wave measurements narrowed down the speed of gravity further?

This answer to How precise are the observational measurements for the speed of gravity? says: ...in 2013 a Chinese group built a model using Earth's tides that helped them narrow it down. ... [T]he ...
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9 votes
2 answers
6k views

### Which star / galaxy is moving away from us the fastest?

I know that we have measured the rate a lot of stars and galaxies move away from us using the doppler shift, and I know that the further a star / galaxy is the faster they accelerate away from us due ...
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4 votes
3 answers
3k views

### What would change if Venus rotated at a speed and direction similar to Earth?

I am interested in two aspects of this question. Imagine that Venus had a similar rotation speed and the same direction of rotation that we have here on Earth. What would change for Venus itself? I'm ...
0 votes
1 answer
109 views

### how to define the universe itself is expanding greater than than the speed of light?

since we observe galaxies and other steller objects in very tiny tiny scale, and how we can understand that the speed of expansion on universe is higher than the speed of light ? even using the ...
• 145
3 votes
1 answer
205 views

### Are there known objects rotating at close-to-light speeds?

For example, $0.1c < v < c$? Is this actually possible? Background: is that true that the black hole in the center of the Milky Way rotates once per 20 minutes?
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1 vote
1 answer
300 views

### Possible to use tachyons to explore black hole?

I read on a Wikipedia article lately that tachyons are theoretical particles which always travel at or above the speed of light. That means that when one passes us, we see two images, a blue shifted ...
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1 vote
0 answers
23 views

### How the Galactic objects are moving? [duplicate]

We know that the Galaxies are moving very fast, not only the Galaxies other known and unknown objects in the universe, are moving. But when it was started where is the starting point, and how it move ...
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0 votes
2 answers
2k views

### Does the edge of the Universe travel faster than the speed of light?

The Universe is expanding faster than the speed of light then does that mean matter at the edge of the universe is also traveling at the speed of light or are ether opposite sides of the universe are ...
• 1
3 votes
2 answers
108 views

### Superluminous super nova output

I was reading about how powerful supernova were and found out there are even bigger supernovae also called hyper nova. A large explosion was discovered in 2016 I believe (or was it 2017). I would ...
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5 votes
4 answers
2k views

### So where are these measurements of galaxies moving faster than light?

https://physics.stackexchange.com/questions/400457/what-does-general-relativity-say-about-the-relative-velocities-of-objects-that-a "we can actually observe galaxies that are moving away from us at >...
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28 votes
1 answer
5k views

### How did Ole Christensen Romer measure the speed of light?

How did Ole Christensen Rømer, who in 1676, shortly after Galileo's death, was said to have measured the speed of light as 220,000 km/s by timing the orbits of Io around Jupiter? My only guess is ...
• 707
0 votes
1 answer
349 views

### What would a black hole merger look like?

Ship 1 is out side the black hole. Ship 2 is nearing a black hole. To ship 1 it would appear that ship 2 would be moving slower to the point it would seem like ship 2 stopped moving the closer to the ...
• 1
3 votes
2 answers
738 views

### When would Oumuamua have entered the solar system?

So from what I've read, Oumuamua travels at around 26km/s when in interstellar space. I also remember reading a while back that Voyager was travelling at around <...
0 votes
2 answers
185 views

### How did Earth get here before gravitational waves?

If GWs propagate at near the speed of light, how did Earth (and its constituent elements) arrive at its current location billions of years before the GW arrived here (or light from distant stars for ...
• 1,072
6 votes
3 answers
3k views

### Does Absolute Velocity Exist?

It seems everyone is on the same page about there being no "absolute velocity" due to the fact that everything is relativistic. However, this leaves me confused. This seems to be disconnected with the ...
1 vote
2 answers
172 views

### Is there any cosmological evidence that neutrinos travel at a speed other than c?

I've been looking into neutrinos. One thing I'm puzzled about is how fast they travel. See the Wikipedia SN1987A article where you can read this: “approximately two to three hours before the visible ...
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11 votes
2 answers
334 views

### How precise are the observational measurements for the speed of gravity?

General Relativity says that gravity moves at the speed of c. How precise are the measurements?
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4 votes
1 answer
215 views

### Does the milky way have relativistic mass against galaxies which are moving away from it at high speeds?

According to the article cited behind, and to a post here in Astronomy SE , there are galaxies moving away from Milky Way faster than light, even at speeds of 2.3c . According to this article Can two ...
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2 votes
1 answer
74 views

### Speed gaseous planets

Why do gaseous planets spin faster than telluric planets? I've seen thats because of primitive nebula but I didn't understand why? Could someone help me? I would appreciate a lot!
2 votes
3 answers
2k views

### Are we already moving faster than light?

Okay, so the speed of revolution of earth around sun is 30 km/s[1], speed of revolution of sun around milky way's center is ~200 km/s[2], speed of rotation of milky way is 828,000 km/h[3] i.e. 230000 ...
10 votes
2 answers
2k views

### Exact measurement of a light year

What is the exact measurement of a light year? I searched google for the answer in meters and came up with $9.461\cdot 10^{15}$ meters. When I calculated the answer considering \$299\,792\,458 \;\text{...
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0 votes
2 answers
770 views

### The light of which star is next to reach the earth?

I heard that the sky wouldn't be dark at night if the light of every star had already reached the earth. Of which (currently invisible) star will the light reach the earth next and when will that be? ...
0 votes
2 answers
160 views

### Regarding the age / size of the Universe [duplicate]

I believe the current estimated age of the Universe is around 14 billion years. I just read in another post on here that the diameter of the Universe is around 90 billion light years. This doesn't ...
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