Connect with us

Instagram

Dark matter: our review suggests it’s time to ditch it in favour of a new theory of gravity

Published

on

The barred spiral galaxy UGC 12158. Wikimedia , CC BY-SA

We can model the motions of planets in the Solar System quite accurately using Newton’s laws of physics. But in the early 1970s, scientists noticed that this didn’t work for disc galaxies – stars at their outer edges, far from the gravitational force of all the matter at their centre – were moving much faster than Newton’s theory predicted.

This made physicists propose that an invisible substance called “dark matter” was providing extra gravitational pull, causing the stars to speed up – a theory that’s become hugely popular. However, in a recent review my colleagues and I suggest that observations across a vast range of scales are much better explained in an alternative theory of gravity proposed by Israeli physicist Mordehai Milgrom in 1982 called Milgromian dynamics or Mond – requiring no invisible matter.

Mond’s main postulate is that when gravity becomes very weak, as occurs at the edge of galaxies, it starts behaving differently from Newtonian physics. In this way, it is possible to explain why stars, planets and gas in the outskirts of over 150 galaxies rotate faster than expected based on just their visible mass. But Mond doesn’t merely explain such rotation curves, in many cases, it predicts them.

Philosophers of science have argued that this power of prediction makes Mond superior to the standard cosmological model, which proposes there is more dark matter in the universe than visible matter. This is because, according to this model, galaxies have a highly uncertain amount of dark matter that depends on details of how the galaxy formed – which we don’t always know. This makes it impossible to predict how quickly galaxies should rotate. But such predictions are routinely made with Mond, and so far these have been confirmed.

Imagine that we know the distribution of visible mass in a galaxy but do not yet know its rotation speed. In the standard cosmological model, it would only be possible to say with some confidence that the rotation speed will come out between 100km/s and 300km/s on the outskirts. Mond makes a more definite prediction that the rotation speed must be in the range 180-190km/s.

If observations later reveal a rotation speed of 188km/s, then this is consistent with both theories – but clearly, Mond is preferred. This is a modern version of Occam’s razor – that the simplest solution is preferable to more complex ones, in this case that we should explain observations with as few “free parameters” as possible. Free parameters are constants – certain numbers that we must plug into equations to make them work. But they are not given by the theory itself – there’s no reason they should have any particular value – so we have to measure them observationally. An example is the gravitation constant, G, in Newton’s gravity theory or the amount of dark matter in galaxies within the standard cosmological model.

We introduced a concept known as “theoretical flexibility” to capture the underlying idea of Occam’s razor that a theory with more free parameters is consistent with a wider range of data – making it more complex. In our review, we used this concept when testing the standard cosmological model and Mond against various astronomical observations, such as the rotation of galaxies and the motions within galaxy clusters.

Each time, we gave a theoretical flexibility score between –2 and +2. A score of –2 indicates that a model makes a clear, precise prediction without peeking at the data. Conversely, +2 implies “anything goes” – theorists would have been able to fit almost any plausible observational result (because there are so many free parameters). We also rated how well each model matches the observations, with +2 indicating excellent agreement and –2 reserved for observations that clearly show the theory is wrong. We then subtract the theoretical flexibility score from that for the agreement with observations, since matching the data well is good – but being able to fit anything is bad.

A good theory would make clear predictions which are later confirmed, ideally getting a combined score of +4 in many different tests (+2 -(-2) = +4). A bad theory would get a score between 0 and -4 (-2 -(+2)= -4). Precise predictions would fail in this case – these are unlikely to work with the wrong physics.

We found an average score for the standard cosmological model of –0.25 across 32 tests, while Mond achieved an average of +1.69 across 29 tests. The scores for each theory in many different tests are shown in figures 1 and 2 below for the standard cosmological model and Mond, respectively.

It is immediately apparent that no major problems were identified for Mond, which at least plausibly agrees with all the data (notice that the bottom two rows denoting falsifications are blank in figure 2).

The problems with dark matter

One of the most striking failures of the standard cosmological model relates to “galaxy bars” – rod-shaped bright regions made of stars – that spiral galaxies often have in their central regions (see lead image). The bars rotate over time. If galaxies were embedded in massive halos of dark matter, their bars would slow down. However, most, if not all, observed galaxy bars are fast. This falsifies the standard cosmological model with very high confidence.

Another problem is that the original models that suggested galaxies have dark matter halos made a big mistake – they assumed that the dark matter particles provided gravity to the matter around it, but were not affected by the gravitational pull of the normal matter. This simplified the calculations, but it doesn’t reflect reality. When this was taken into account in subsequent simulations it was clear that dark matter halos around galaxies do not reliably explain their properties.

There are many other failures of the standard cosmological model that we investigated in our review, with Mond often able to naturally explain the observations. The reason the standard cosmological model is nevertheless so popular could be down to computational mistakes or limited knowledge about its failures, some of which were discovered quite recently. It could also be due to people’s reluctance to tweak a gravity theory that has been so successful in many other areas of physics.

The huge lead of Mond over the standard cosmological model in our study led us to conclude that Mond is strongly favoured by the available observations. While we do not claim that Mond is perfect, we still think it gets the big picture correct – galaxies really do lack dark matter.The Conversation

Indranil Banik, Postdoctoral Research Fellow of Astrophysics, University of St Andrews

This article is republished from The Conversation under a Creative Commons license. Read the original article.

xosotin chelseathông tin chuyển nhượngcâu lạc bộ bóng đá arsenalbóng đá atalantabundesligacầu thủ haalandUEFAevertonxosofutebol ao vivofutemaxmulticanaisonbethttps://bsport.fithttps://onbet88.ooohttps://i9bet.bizhttps://hi88.ooohttps://okvip.athttps://f8bet.athttps://fb88.cashhttps://vn88.cashhttps://shbet.atbóng đá world cupbóng đá inter milantin juventusbenzemala ligaclb leicester cityMUman citymessi lionelsalahnapolineymarpsgronaldoserie atottenhamvalenciaAS ROMALeverkusenac milanmbappenapolinewcastleaston villaliverpoolfa cupreal madridpremier leagueAjaxbao bong da247EPLbarcelonabournemouthaff cupasean footballbên lề sân cỏbáo bóng đá mớibóng đá cúp thế giớitin bóng đá ViệtUEFAbáo bóng đá việt namHuyền thoại bóng đágiải ngoại hạng anhSeagametap chi bong da the gioitin bong da lutrận đấu hôm nayviệt nam bóng đátin nong bong daBóng đá nữthể thao 7m24h bóng đábóng đá hôm naythe thao ngoai hang anhtin nhanh bóng đáphòng thay đồ bóng đábóng đá phủikèo nhà cái onbetbóng đá lu 2thông tin phòng thay đồthe thao vuaapp đánh lô đềdudoanxosoxổ số giải đặc biệthôm nay xổ sốkèo đẹp hôm nayketquaxosokq xskqxsmnsoi cầu ba miềnsoi cau thong kesxkt hôm naythế giới xổ sốxổ số 24hxo.soxoso3mienxo so ba mienxoso dac bietxosodientoanxổ số dự đoánvé số chiều xổxoso ket quaxosokienthietxoso kq hôm nayxoso ktxổ số megaxổ số mới nhất hôm nayxoso truc tiepxoso ViệtSX3MIENxs dự đoánxs mien bac hom nayxs miên namxsmientrungxsmn thu 7con số may mắn hôm nayKQXS 3 miền Bắc Trung Nam Nhanhdự đoán xổ số 3 miềndò vé sốdu doan xo so hom nayket qua xo xoket qua xo so.vntrúng thưởng xo sokq xoso trực tiếpket qua xskqxs 247số miền nams0x0 mienbacxosobamien hôm naysố đẹp hôm naysố đẹp trực tuyếnnuôi số đẹpxo so hom quaxoso ketquaxstruc tiep hom nayxổ số kiến thiết trực tiếpxổ số kq hôm nayso xo kq trực tuyenkết quả xổ số miền bắc trực tiếpxo so miền namxổ số miền nam trực tiếptrực tiếp xổ số hôm nayket wa xsKQ XOSOxoso onlinexo so truc tiep hom nayxsttso mien bac trong ngàyKQXS3Msố so mien bacdu doan xo so onlinedu doan cau loxổ số kenokqxs vnKQXOSOKQXS hôm naytrực tiếp kết quả xổ số ba miềncap lo dep nhat hom naysoi cầu chuẩn hôm nayso ket qua xo soXem kết quả xổ số nhanh nhấtSX3MIENXSMB chủ nhậtKQXSMNkết quả mở giải trực tuyếnGiờ vàng chốt số OnlineĐánh Đề Con Gìdò số miền namdò vé số hôm nayso mo so debach thủ lô đẹp nhất hôm naycầu đề hôm naykết quả xổ số kiến thiết toàn quốccau dep 88xsmb rong bach kimket qua xs 2023dự đoán xổ số hàng ngàyBạch thủ đề miền BắcSoi Cầu MB thần tàisoi cau vip 247soi cầu tốtsoi cầu miễn phísoi cau mb vipxsmb hom nayxs vietlottxsmn hôm naycầu lô đẹpthống kê lô kép xổ số miền Bắcquay thử xsmnxổ số thần tàiQuay thử XSMTxổ số chiều nayxo so mien nam hom nayweb đánh lô đề trực tuyến uy tínKQXS hôm nayxsmb ngày hôm nayXSMT chủ nhậtxổ số Power 6/55KQXS A trúng roycao thủ chốt sốbảng xổ số đặc biệtsoi cầu 247 vipsoi cầu wap 666Soi cầu miễn phí 888 VIPSoi Cau Chuan MBđộc thủ desố miền bắcthần tài cho sốKết quả xổ số thần tàiXem trực tiếp xổ sốXIN SỐ THẦN TÀI THỔ ĐỊACầu lô số đẹplô đẹp vip 24hsoi cầu miễn phí 888xổ số kiến thiết chiều nayXSMN thứ 7 hàng tuầnKết quả Xổ số Hồ Chí Minhnhà cái xổ số Việt NamXổ Số Đại PhátXổ số mới nhất Hôm Nayso xo mb hom nayxxmb88quay thu mbXo so Minh ChinhXS Minh Ngọc trực tiếp hôm nayXSMN 88XSTDxs than taixổ số UY TIN NHẤTxs vietlott 88SOI CẦU SIÊU CHUẨNSoiCauVietlô đẹp hôm nay vipket qua so xo hom naykqxsmb 30 ngàydự đoán xổ số 3 miềnSoi cầu 3 càng chuẩn xácbạch thủ lônuoi lo chuanbắt lô chuẩn theo ngàykq xo-solô 3 càngnuôi lô đề siêu vipcầu Lô Xiên XSMBđề về bao nhiêuSoi cầu x3xổ số kiến thiết ngày hôm nayquay thử xsmttruc tiep kết quả sxmntrực tiếp miền bắckết quả xổ số chấm vnbảng xs đặc biệt năm 2023soi cau xsmbxổ số hà nội hôm naysxmtxsmt hôm nayxs truc tiep mbketqua xo so onlinekqxs onlinexo số hôm nayXS3MTin xs hôm nayxsmn thu2XSMN hom nayxổ số miền bắc trực tiếp hôm naySO XOxsmbsxmn hôm nay188betlink188 xo sosoi cầu vip 88lô tô việtsoi lô việtXS247xs ba miềnchốt lô đẹp nhất hôm naychốt số xsmbCHƠI LÔ TÔsoi cau mn hom naychốt lô chuẩndu doan sxmtdự đoán xổ số onlinerồng bạch kim chốt 3 càng miễn phí hôm naythống kê lô gan miền bắcdàn đề lôCầu Kèo Đặc Biệtchốt cầu may mắnkết quả xổ số miền bắc hômSoi cầu vàng 777thẻ bài onlinedu doan mn 888soi cầu miền nam vipsoi cầu mt vipdàn de hôm nay7 cao thủ chốt sốsoi cau mien phi 7777 cao thủ chốt số nức tiếng3 càng miền bắcrồng bạch kim 777dàn de bất bạion newsddxsmn188betw88w88789bettf88sin88suvipsunwintf88five8812betsv88vn88Top 10 nhà cái uy tínsky88iwinlucky88nhacaisin88oxbetm88vn88w88789betiwinf8betrio66rio66lucky88oxbetvn88188bet789betMay-88five88one88sin88bk88xbetoxbetMU88188BETSV88RIO66ONBET88188betM88M88SV88Jun-68Jun-88one88iwinv9betw388OXBETw388w388onbetonbetonbetonbet88onbet88onbet88onbet88onbetonbetonbetonbetqh88mu88Nhà cái uy tínpog79vp777vp777vipbetvipbetuk88uk88typhu88typhu88tk88tk88sm66sm66me88me888live8live8livesm66me88win798livesm66me88win79pog79pog79vp777vp777uk88uk88tk88tk88luck8luck8kingbet86kingbet86k188k188hr99hr99123b8xbetvnvipbetsv66zbettaisunwin-vntyphu88vn138vwinvwinvi68ee881xbetrio66zbetvn138i9betvipfi88clubcf68onbet88ee88typhu88onbetonbetkhuyenmai12bet-moblie12betmoblietaimienphi247vi68clupcf68clupvipbeti9betqh88onb123onbefsoi cầunổ hũbắn cáđá gàđá gàgame bàicasinosoi cầuxóc đĩagame bàigiải mã giấc mơbầu cuaslot gamecasinonổ hủdàn đềBắn cácasinodàn đềnổ hũtài xỉuslot gamecasinobắn cáđá gàgame bàithể thaogame bàisoi cầukqsssoi cầucờ tướngbắn cágame bàixóc đĩaAG百家乐AG百家乐AG真人AG真人爱游戏华体会华体会im体育kok体育开云体育开云体育开云体育乐鱼体育乐鱼体育欧宝体育ob体育亚博体育亚博体育亚博体育亚博体育亚博体育亚博体育开云体育开云体育棋牌棋牌沙巴体育买球平台新葡京娱乐开云体育mu88qh88
Continue Reading
Click to comment

Leave a Reply

Your email address will not be published. Required fields are marked *

Maria in Vancouver

Lifestyle2 weeks ago

Nobody Wants This…IRL (In Real Life)

Just like everyone else who’s binged on Netflix series, “Nobody Wants This” — a romcom about a newly single rabbi...

Lifestyle3 weeks ago

Family Estrangement: Why It’s Okay

Family estrangement is the absence of a previously long-standing relationship between family members via emotional or physical distancing to the...

Lifestyle2 months ago

Becoming Your Best Version

By Matter Laurel-Zalko As a woman, I’m constantly evolving. I’m constantly changing towards my better version each year. Actually, I’m...

Lifestyle2 months ago

The True Power of Manifestation

I truly believe in the power of our imagination and that what we believe in our lives is an actual...

Maria in Vancouver3 months ago

DECORATE YOUR HOME 101

By Matte Laurel-Zalko Our home interiors are an insight into our brains and our hearts. It is our own collaboration...

Maria in Vancouver4 months ago

Guide to Planning a Wedding in 2 Months

By Matte Laurel-Zalko Are you recently engaged and find yourself in a bit of a pickle because you and your...

Maria in Vancouver4 months ago

Staying Cool and Stylish this Summer

By Matte Laurel-Zalko I couldn’t agree more when the great late Ella Fitzgerald sang “Summertime and the livin’ is easy.”...

Maria in Vancouver5 months ago

Ageing Gratefully and Joyfully

My 56th trip around the sun is just around the corner! Whew. Wow. Admittedly, I used to be afraid of...

Maria in Vancouver6 months ago

My Love Affair With Pearls

On March 18, 2023, my article, The Power of Pearls was published. In that article, I wrote about the history...

Maria in Vancouver6 months ago

7 Creative Ways to Propose!

Sometime in April 2022, my significant other gave me a heads up: he will be proposing to me on May...