Speed of gravity: Difference between revisions - Wikipedia

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{{infobox| title = Speed of gravity

| image =

| caption =

| header1 = Exact values

|labelstyle = font-weight:normal

| label2 = [[Metre per second|metres per second]]

| data2 = {{val|299792458}}

| header4 = Approximate values (to three significant digits)

| label5 = [[kilometres per hour]]

| data5 = {{val|1080000000}}

| label6 = [[miles per hour|miles per second]]

| data6 = {{val|186000}}

| label7 = [[miles per hour]]<ref>{{cite book |title=Elementary and Intermediate Algebra: A Combined Course, Student Support Edition |edition=4th illustrated |first1=Ron |last1=Larson |first2=Robert P. |last2=Hostetler |publisher=Cengage Learning |year=2007 |isbn=978-0-618-75354-3 |page=197 |url=https://books.google.com/books?id=qe-YvKoeiasC&pg=PA179}}</ref>

| data7 = {{val|671000000}}

| label8 = [[astronomical unit]]s per day

| data8 = 173{{#tag:ref|Exact value: {{nowrap|({{val|299792458}} × 60 × 60 × 24 / {{val|149597870700}}) AU/day}}|group="Note"}}

| label9 = [[parsec]]s per year

| data9 = 0.307{{#tag:ref|Exact value: {{nowrap|({{val|999992651}}π / {{val|10246429500}}) pc/y}}|group="Note"}}

| header10 = Approximate light signal travel times

| label11 = '''Distance'''

| data11 = '''Time'''

| label12 = one [[Foot (unit)|foot]]

| data12 = 1.0 [[Nanosecond|ns]]

| label13 = one [[metre]]

| data13 = 3.3 ns

| label15 = from [[geostationary orbit]] to Earth

| data15 = 119 [[millisecond|ms]]

| label16 = the length of Earth's [[equator]]

| data16 = 134 ms

| label17 = from [[Moon]] to Earth

| data17 = 1.3 [[second|s]]

| label18 = from [[Sun]] to Earth (1 [[astronomical unit|AU]])

| data18 = 8.3 [[minute|min]]

| label20 = one [[light year]]

| data20 = 1.0 year

| label21 = one [[parsec]]

| data21 = 3.26 years

| label22 = from [[Proxima Centauri|nearest star]] to Sun ({{nowrap|1.3 pc}})

| data22 = 4.2 years

| label23 = from the nearest galaxy (the [[Canis Major Dwarf Galaxy]]) to Earth

| data23 = {{val|25,000|u=years}}

| label24 = across the [[Milky Way]]

| data24 = {{val|100,000|u=years}}

| label25 = from the [[Andromeda Galaxy]] to Earth

| data25 = 2.5 million years

}}

{{short description|Physical constant equal to the speed of light}}

In [[classical theories of gravitation]], the [[gravitational wave|changes]] in a [[gravitational field]] propagate. A change in the distribution of [[energy]] and [[momentum]] of matter results in subsequent alteration, at a distance, of the gravitational field which it produces. In the relativistic sense, the "speed of gravity" refers to the speed of a [[gravitational wave]], which, as predicted by [[general relativity]] and confirmed by observation of the [[GW170817|GW170817 neutron star merger]], is the same speed<ref>{{cite journal |author = Flanagan E.E., Hughes S.A. | year = 2005 |title = The basics of gravitational wave theory |journal = [[New Journal of Physics]] |volume = 7 |issue = 1| page = 204 |doi = 10.1088/1367-2630/7/1/204 |bibcode = 2005NJPh....7..204F |doi-access = free }}</ref> as the [[speed of light]] (''c'').