Berliner Boersenzeitung - Astronomers reveal evidence of universe's 'background hum'

EUR -
AED 4.26841
AFN 80.362394
ALL 97.542216
AMD 446.735356
ANG 2.080099
AOA 1065.794205
ARS 1494.414015
AUD 1.776887
AWG 2.092071
AZN 1.980459
BAM 1.954642
BBD 2.348809
BDT 141.226338
BGN 1.956132
BHD 0.43854
BIF 3466.946195
BMD 1.162261
BND 1.493215
BOB 8.038238
BRL 6.486005
BSD 1.163311
BTN 100.147673
BWP 15.618748
BYN 3.807045
BYR 22780.325028
BZD 2.336716
CAD 1.596076
CDF 3354.287055
CHF 0.932807
CLF 0.029182
CLP 1120.296341
CNY 8.342655
CNH 8.346165
COP 4674.330945
CRC 587.052233
CUC 1.162261
CUP 30.799929
CVE 110.199718
CZK 24.634179
DJF 206.947405
DKK 7.463699
DOP 70.258379
DZD 151.514244
EGP 57.439973
ERN 17.433922
ETB 161.636047
FJD 2.620788
FKP 0.864949
GBP 0.866519
GEL 3.150183
GGP 0.864949
GHS 12.127816
GIP 0.864949
GMD 83.106172
GNF 10094.020343
GTQ 8.931709
GYD 243.385819
HKD 9.121487
HNL 30.445964
HRK 7.532663
HTG 152.739518
HUF 398.923459
IDR 18977.696027
ILS 3.908598
IMP 0.864949
INR 100.127437
IQD 1523.897249
IRR 48945.741055
ISK 142.354235
JEP 0.864949
JMD 186.029797
JOD 0.824089
JPY 172.932309
KES 150.300962
KGS 101.640213
KHR 4662.238109
KMF 491.989694
KPW 1046.046309
KRW 1616.942576
KWD 0.355234
KYD 0.969426
KZT 620.152624
LAK 25087.138481
LBP 104232.653
LKR 350.972086
LRD 233.241828
LSL 20.596898
LTL 3.431856
LVL 0.703041
LYD 6.327252
MAD 10.519168
MDL 19.788278
MGA 5176.933206
MKD 61.523554
MMK 2439.678938
MNT 4168.013035
MOP 9.404829
MRU 46.275587
MUR 53.119698
MVR 17.903172
MWK 2017.205016
MXN 21.777182
MYR 4.935007
MZN 74.338683
NAD 20.596898
NGN 1779.387897
NIO 42.814637
NOK 11.838157
NPR 160.236077
NZD 1.94976
OMR 0.446894
PAB 1.163311
PEN 4.140847
PGK 4.817146
PHP 66.377189
PKR 331.310933
PLN 4.244785
PYG 9003.666265
QAR 4.229694
RON 5.072695
RSD 117.080642
RUB 91.265035
RWF 1681.00418
SAR 4.36165
SBD 9.64543
SCR 17.082281
SDG 697.942292
SEK 11.245095
SGD 1.492813
SHP 0.913355
SLE 26.62005
SLL 24372.046713
SOS 664.806172
SRD 43.245469
STD 24056.466061
STN 24.485495
SVC 10.17897
SYP 15112.803405
SZL 20.592801
THB 37.628259
TJS 11.196867
TMT 4.079538
TND 3.419874
TOP 2.722137
TRY 46.947496
TTD 7.897322
TWD 34.181766
TZS 3030.404801
UAH 48.58252
UGX 4168.530579
USD 1.162261
UYU 46.882227
UZS 14725.276806
VES 135.943958
VND 30404.760344
VUV 138.92149
WST 3.080055
XAF 655.568644
XAG 0.030448
XAU 0.000347
XCD 3.14107
XCG 2.096558
XDR 0.815317
XOF 655.568644
XPF 119.331742
YER 280.163552
ZAR 20.586499
ZMK 10461.752209
ZMW 26.785133
ZWL 374.247723
  • CMSC

    0.0900

    22.314

    +0.4%

  • CMSD

    0.0250

    22.285

    +0.11%

  • RBGPF

    0.0000

    69.04

    0%

  • SCS

    0.0400

    10.74

    +0.37%

  • RELX

    0.0300

    53

    +0.06%

  • RIO

    -0.1400

    59.33

    -0.24%

  • GSK

    0.1300

    41.45

    +0.31%

  • NGG

    0.2700

    71.48

    +0.38%

  • BP

    0.1750

    30.4

    +0.58%

  • BTI

    0.7150

    48.215

    +1.48%

  • BCC

    0.7900

    91.02

    +0.87%

  • JRI

    0.0200

    13.13

    +0.15%

  • VOD

    0.0100

    9.85

    +0.1%

  • BCE

    -0.0600

    22.445

    -0.27%

  • RYCEF

    0.1000

    12

    +0.83%

  • AZN

    -0.1200

    73.71

    -0.16%

Astronomers reveal evidence of universe's 'background hum'
Astronomers reveal evidence of universe's 'background hum' / Photo: GUILLAUME SOUVANT - AFP/File

Astronomers reveal evidence of universe's 'background hum'

Astronomers across the world announced on Thursday that they have found the first evidence of a long-theorised form of gravitational waves that create a "background hum" rumbling throughout the universe.

Text size:

The breakthrough -- made by hundreds of scientists using radio telescopes in North America, Europe, China, India and Australia after years of work -- was hailed as a major milestone that opens a new window into the universe.

First predicted by Albert Einstein more than a century ago, gravitational waves are ripples in the fabric of the universe that travel through everything at the speed of light almost entirely unimpeded.

Their existence was not confirmed until 2015, when the US and Italian observatories detected the first gravitational waves created by two black holes colliding.

These "high-frequency" waves were the result of a single violent event that sends a strong, short burst rippling towards Earth.

But for decades scientists have been searching for low-frequency gravitational waves, thought to be constantly rolling through space like background noise.

Joining forces under the banner of the International Pulsar Timing Array consortium, scientists working at gravitational wave detectors on several continents revealed on Thursday they have finally found strong evidence of these background waves.

"We now know that the universe is awash with gravitational waves," Michael Keith of the European Pulsar Timing Array told AFP.

- Using dead stars as clocks -

As gravitational waves travel through space, they very subtly squeeze and stretch everything they pass through.

To find evidence of this squeezing and stretching at low frequencies, astronomers looked at pulsars, the dead cores of stars that exploded in a supernova.

Some spin hundreds of times a second, flashing beams of radio waves at extremely regular intervals, like cosmic lighthouses.

This means they can act as "a very, very precise clock," Keith said.

For the new research, radio telescopes around the world were aimed at a total of 115 pulsars throughout the Milky Way.

Scientists then measured the incredibly small differences in the timing of the pulses, searching for telltale signs of gravitational waves.

French astrophysicist Antoine Petiteau said they were able to "detect changes of less than one millionth of a second across more than 20 years".

Maura McLaughlin of the US Pulsar Search Collaboratory programme said they were "awestruck" after first seeing evidence of the waves in 2020.

It was "really a magical moment," she told a press conference.

The early evidence was consistent with Einstein's theory of relativity and science's current understanding of the universe, the scientists said.

But they emphasised they have not yet definitively "detected" the waves, because they have not reached the gold-standard five sigma level of certainty. Five sigma indicates that there is a one-in-a-million chance of something being a statistical fluke.

"We're frustratingly just shy of the mark," Keith said, adding that there was a 99-percent probability that the evidence points to gravitational waves.

Each country or group in the consortium published their research separately in a range of journals.

Steve Taylor, chair of North America's NANOGrav gravitational wave observatory, said that once all the data was combined, the five sigma mark could be reached in a year or two.

- 'Like sitting in a noisy restaurant' -

The leading theory is that the waves are coming from pairs of supermassive black holes sitting at the centre of galaxies that are slowly merging.

Unlike those that caused the previously detected gravitational waves, these black holes are almost unimaginably huge -- sometimes billions of times bigger than the Sun.

Daniel Reardon, a member of Australia's Parkes Pulsar Timing Array, told AFP that -- if confirmed -- the waves would be "the sum of all of the supermassive black hole binary systems whirling around each other at the cores of galaxies everywhere in the universe".

Keith said the "background hum of all these black holes" was "like sitting in a noisy restaurant and hearing all these people talking".

Another theory is that the gravitational waves could be from the rapid expansion that came within a second after the Big Bang, a period called cosmic inflation that is hidden from the view of scientists.

Keith said the galaxies between Earth and the Big Bang were likely "drowning out" such waves.

But in the future, low-frequency gravitational waves could reveal more about this early expansion and possibly shed light on the mystery of dark matter, the scientists said.

It could also help them understand more about how black holes and galaxies form and evolve.

(B.Hartmann--BBZ)